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Efficient construction of SiC membranes to filtrate high-temperature dust-laden gas for environmental sustainability
Shiying Ni, Yuqi Song, Dong Zou, Zhaoxiang Zhong, Weihong Xing
 doi: 10.1016/j.gee.2025.08.003
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Abstract:
During the production processes of energy, metallurgy, chemical engineering, and other process industries, substantial high-temperature dust-laden flue gas is generated. Asymmetric silicon carbide (SiC) membranes exhibit significant potential in flue gas filtration since they enable direct filtration of high-temperature gas and facilitate thermal energy recovery. However, membrane particle penetration is a prevalent issue when constructing membrane layer directly on macroporous support, which contributes to a considerable mass transfer resistance. Herein, a novel hydrophobic modification strategy was developed to avoid the slurry penetration, thereby fabricating the asymmetric SiC membrane without the necessity of any intermediate or sacrificial layer. Firstly, the modifier concentration was adjusted to guarantee that the support was hydrophobic enough to prevent the slurry from penetrating. Subsequently, the slurry surface tension was fine-tuned by introducing ethanol to enhance the integrity of the SiC membrane. Furthermore, the effect of solid content was systematically investigated. It was demonstrated that the optimized SiC membranes obtained excellent gas permeance from 100.8 to 199.8 m3·m−2·h−1·kPa−1 with the pore size ranging from 1.93 to 3.89 μm. Also, the SiC membrane exhibited excellent stability for 24 h and achieved an excellent dust removal efficiency (99.99%) when filtering ultrafine dust particles (∼300 nm) under high temperatures. This method effectively bridges the membrane particle penetration issue caused by the particle size disparity among different layers of the asymmetric membrane, establishing an efficient strategy to fabricate high-permeance SiC membranes applied in high-temperature dust-laden gas filtration.
High-valent cobalt-oxo species mediated selective oxidation of glucose to chemicals in photocatalytic Fenton-like system
Tianliang Xia, Chengxu Wang, Xinyu Bai, Meiting Ju, Hengli Qian, Ruite Lai, Chao Xie, Guanjie Yu, Yao Tang, Fei Qu, Chaojie Zhang, Shuwen Zhou, Haijiao Xie, Shaolan Song, Qidong Hou
 doi: 10.1016/j.gee.2025.08.001
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Peroxymonosulfate (PMS)-based Fenton-like technologies have been increasingly employed in the upgrading of biomass, but they are commonly limited by the trade-off between conversion and selectivity due to the short lifetime of reactive oxygen species (ROS) and uncontrollable oxidation pathways. Herein, we show that single-atom Co supported on carbon nitride enables the high-valent-oxo cobalt species (Co(IV)=O) mediated oxidation of glucose into value-added products in acetonitrile. This photocatalytic Fenton-like system achieved an overall selectivity of gluconic acid, glucaric acid, arabinose, and formic acid up to 90.3% at glucose conversion of 69.6%, outperforming most of previously reported catalytic systems. The small amount (0.72 wt%) of single-atom Co could not only elevate the optical absorption and the efficiency of photo-generated carriers separation but also induce the efficient generation of Co(IV)=O with reduced ROS to enable efficient and selective oxidation. These findings prove the great promise of high-valent metal-oxo species in biomass conversions.
The Need to Consider Regional Supply Chains and Water Usage in H2-Steel Transition
Peng Peng, Tae Lim, Fabian Rosner, Hanna Breunig, Prakash Rao, Arman Shehabi
 doi: 10.1016/j.gee.2025.08.002
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The iron and steel industry is one of the largest contributors to U.S. and global greenhouse gas emissions. Hydrogen can act as a promising reducing agent and clean energy carrier to decarbonize this sector, and has received significant attention in terms of process modelling, techno-economic analysis, and life cycle assessment in recent years. Policy incentives, hydrogen storage and transportation, and water stress levels are key factors that require significantly more consideration in order to realize hydrogen’s potential to decarbonize this industry. This review demonstrates the need for a systematic understanding and critical assessment of these areas, and their profound impacts on the decarbonization of the iron and steel sector. Furthermore, hydrogen and water supply face competition from other hard-to-decarbonize sectors, which should be considered on national and regional levels. Lastly, future research should also consider the impact of other environmental factors and hydrogen leak when deploying hydrogen at scale for industrial decarbonization.
Selective oxidation of high-concentration 5-hydroxymethylfurfural to 2,5-furan dicarboxylic acid at room temperature in water by synergic electronic effect of bimetallic RuCo/NC catalyst
Lihua Du, Conghao Ku, Mengmeng Feng, Junjie Lan, Jeunghee Park, Ik Seon Kwon, Lingzhao Kong, Weiran Yang
 doi: 10.1016/j.gee.2025.07.008
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Abstract:
Bio-based 2,5-furandicarboxylic acid (FDCA) has the potential to replace petroleum-based terephthalic acid for the synthesis of high-performance polyester materials, demonstrating broad application prospects. Its primary preparation method involves the selective oxidation of 5-hydroxymethylfurfural (HMF). However, the industrial process is limited by low HMF concentration during the reaction due to the formation of humus resulting from HMF instability especially in high concentration. In this study, a RuCo/NC bimetallic catalyst was fabricated, which can effectively catalyze the selective oxidation of HMF to obtain FDCA at room temperature (25 °C). Side reactions caused by HMF instability were significantly reduced at room temperature, allowing for the application of high-concentration HMF (10 wt%) to achieve an excellent FDCA yield of 91.92% in water. Mechanism studies reveal that a synergistic electronic effect exists between two metals that electrons transfer from Co to Ru to increase the electron density on the surface of Ru nanoparticles, improving oxygen activation ability. Meanwhile, the electron-deficient Co further enhances the adsorption of HMF on the catalyst surface for better reactivity. This study realized the high-concentration HMF aerobic oxidation to FDCA at room temperature in water, paving the way for FDCA to serve as a sustainable substitute for terephthalic acid in polyester production.
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Catalytic conversion of lignocellulosic biomass into chemicals and fuels
Weiping Deng, Yunchao Feng, Jie Fu, Haiwei Guo, Yong Guo, Buxing Han, Zhicheng Jiang, Lingzhao Kong, Changzhi Li, Haichao Liu, Phuc T.T. Nguyen, Puning Ren, Feng Wang, Shuai Wang, Yanqin Wang, Ye Wang, Sie Shing Wong, Kai Yan, Ning Yan, Xiaofei Yang, Yuanbao Zhang, Zhanrong Zhang, Xianhai Zeng, Hui Zhou
2023, 8(1): 10-114.   doi: 10.1016/j.gee.2022.07.003
[Abstract](1375) [PDF 23019KB](92)
摘要:
In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future, lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a promising feedstock. This review focuses on the state-of-the-art catalytic transformation of lignocellulosic biomass into value-added chemicals and fuels. Following a brief introduction on the structure, major resources and pretreatment methods of lignocellulosic biomass, the catalytic conversion of three main components, i.e., cellulose, hemicellulose and lignin, into various compounds are comprehensively discussed. Either in separate steps or in one-pot, cellulose and hemicellulose are hydrolyzed into sugars and upgraded into oxygen-containing chemicals such as 5-HMF, furfural, polyols, and organic acids, or even nitrogen-containing chemicals such as amino acids. On the other hand, lignin is first depolymerized into phenols, catechols, guaiacols, aldehydes and ketones, and then further transformed into hydrocarbon fuels, bioplastic precursors and bioactive compounds. The review then introduces the transformations of whole biomass via catalytic gasification, catalytic pyrolysis, as well as emerging strategies. Finally, opportunities, challenges and prospective of woody biomass valorization are highlighted.
Application of deep eutectic solvents in biomass pretreatment and conversion
Yu Chen, Tiancheng Mu
2019, 4(2): 95-115.   doi: 10.1016/j.gee.2019.01.012
[Abstract](829) [FullText HTML](357) [PDF 3331KB](120)
摘要:
Biomass is renewable, abundant, cheap, biocompatible, and biodegradable materials and has been used to produce chemicals, materials, energy, and fuels. However, most of the biomass, especially most of the biomass polymers are not soluble in common solvents, which hinders their pretreatment and conversion. Deep eutectic solvents (DESs) are environmental-friendly, cheap, and highly tunable, with high solubility, which renders them potential applications in biomass pretreatment and conversion. They could be used as solvents or catalysts and so on. This paper intends to review the application of DESs for the pretreatment of biomass and conversion of biomass to value-added products. We focus on the following topics related to biomass and DESs: (1) DESs for the pretreatment of biomass; (2) DESs for the dissolution and separation of biomass or extraction of chemicals from biomass; (3) DESs for biomass conversion; (4) Drawbacks, and recyclability of DESs for pretreatment and conversion of biomass.
Synthesis and applications of MOF-derived porous nanostructures
Min Hui Yap, Kam Loon Fow, George Zheng Chen
2017, 2(3): 218-245.   doi: 10.1016/j.gee.2017.05.003
[Abstract](599) [FullText HTML](240) [PDF 6267KB](102)
摘要:
Metal organic frameworks (MOFs) represent a class of porous material which is formed by strong bonds between metal ions and organic linkers. By careful selection of constituents, MOFs can exhibit very high surface area, large pore volume, and excellent chemical stability. Research on synthesis, structures and properties of various MOFs has shown that they are promising materials for many applications, such as energy storage, gas storage, heterogeneous catalysis and sensing. Apart from direct use, MOFs have also been used as support substrates for nanomaterials or as sacrificial templates/precursors for preparation of various functional nanostructures. In this review, we aim to present the most recent development of MOFs as precursors for the preparation of various nanostructures and their potential applications in energy-related devices and processes. Specifically, this present survey intends to push the boundaries and covers the literatures from the year 2013 to early 2017, on supercapacitors, lithium ion batteries, electrocatalysts, photocatalyst, gas sensing, water treatment, solar cells, and carbon dioxide capture. Finally, an outlook in terms of future challenges and potential prospects towards industrial applications are also discussed.
Overview of acidic deep eutectic solvents on synthesis, properties and applications
Hao Qin, Xutao Hu, Jingwen Wang, Hongye Cheng, Lifang Chen, Zhiwen Qi
2020, 5(1): 8-21.   doi: 10.1016/j.gee.2019.03.002
[Abstract](869) [FullText HTML](381) [PDF 1576KB](111)
摘要:
This review divides the acidic deep eutectic solvents (ADES) into Brønsted and Lewis DES according to their diversity of acidic character. The hydrogen bond donors and halide salts for formulating an ADES are classified, the synthesis methods are described, and the physicochemical properties including freezing point, acidity, density, viscosity and conductivity are presented. Furthermore, the applications of Brønsted acidic deep eutectic solvents (BADES) and Lewis acidic deep eutectic solvents (LADES) are overviewed, respectively, covering the fields in dissolution, extraction, organic reaction and metal electrodeposition. It is expected that the ADES has great potential to replace the pollutional mineral acid, expensive and unstable solid acid, and costly ionic liquid in many acid-employed chemical processes, thus meeting the demands of green chemistry.
A comprehensive review on recent progress in aluminum–air batteries
Yisi Liu, Qian Sun, Wenzhang Li, Keegan R. Adair, Jie Li, Xueliang Sun
2017, 2(3): 246-277.   doi: 10.1016/j.gee.2017.06.006
[Abstract](853) [FullText HTML](389) [PDF 14207KB](166)
摘要:
The aluminum–air battery is considered to be an attractive candidate as a power source for electric vehicles (EVs) because of its high theoretical energy density (8100 Wh kg−1), which is significantly greater than that of the state-of-the-art lithium-ion batteries (LIBs). However, some technical and scientific problems preventing the large-scale development of Al–air batteries have not yet to be resolved. In this review, we present the fundamentals, challenges and the recent advances in Al–air battery technology from aluminum anode, air cathode and electrocatalysts to electrolytes and inhibitors. Firstly, the alloying of aluminum with transition metal elements is reviewed and shown to reduce the self-corrosion of Al and improve battery performance. Additionally for the cathode, extensive studies of electrocatalytic materials for oxygen reduction/evolution including Pt and Pt alloys, nonprecious metal catalysts, and carbonaceous materials at the air cathode are highlighted. Moreover, for the electrolyte, the application of aqueous and nonaqueous electrolytes in Al–air batteries are discussed. Meanwhile, the addition of inhibitors to the electrolyte to enhance electrochemical performance is also explored. Finally, the challenges and future research directions are proposed for the further development of Al–air batteries.
Progress in aqueous rechargeable batteries
Jilei Liu, Chaohe Xu, Zhen Chen, Shibing Ni, Ze Xiang Shen
2018, 3(1): 20-41.   doi: 10.1016/j.gee.2017.10.001
[Abstract](408) [FullText HTML](162) [PDF 6967KB](80)
摘要:
Over the past decades, a series of aqueous rechargeable batteries (ARBs) were explored, investigated and demonstrated. Among them, aqueous rechargeable alkali-metal ion (Li+, Na+, K+) batteries, aqueous rechargeable-metal ion (Zn2+, Mg2+, Ca2+, Al3+) batteries and aqueous rechargeable hybrid batteries are standing out due to peculiar properties. In this review, we focus on the fundamental basics of these batteries, and discuss the scientific and/or technological achievements and challenges. By critically reviewing state-of-the-art technologies and the most promising results so far, we aim to analyze the benefits of ARBs and the critical issues to be addressed, and to promote better development of ARBs.
Cellulose-based materials in wastewater treatment of petroleum industry
Baoliang Peng, Zhaoling Yao, Xiaocong Wang, Mitchel Crombeen, Dalton G. Sweeney, Kam Chiu Tam
2020, 5(1): 37-49.   doi: 10.1016/j.gee.2019.09.003
[Abstract](430) [FullText HTML](190) [PDF 2482KB](65)
摘要:
The most abundant natural biopolymer on earth, cellulose fiber, may offer a highly efficient, low-cost, and chemical-free option for wastewater treatment. Cellulose is widely distributed in plants and several marine animals. It is a carbohydrate polymer consisting of β-1,4-linked anhydro-D-glucose units with three hydroxyl groups per anhydroglucose unit (AGU). Cellulose-based materials have been used in food, industrial, pharmaceutical, paper, textile production, and in wastewater treatment applications due to their low cost, renewability, biodegradability, and non-toxicity. For water treatment in the oil and gas industry, cellulose-based materials can be used as adsorbents, flocculants, and oil/water separation membranes. In this review, the uses of cellulose-based materials for wastewater treatment in the oil & gas industry are summarized, and recent research progress in the following aspects are highlighted: crude oil spill cleaning, flocculation of solid suspended matter in drilling or oil recovery in the upstream oil industry, adsorption of heavy metal or chemicals, and separation of oil/water by cellulosic membrane in the downstream water treatment.
Recent progress on synthesis of ZIF-67-based materials and their application to heterogeneous catalysis
Chongxiong Duan, Yi Yu, Han Hu
2022, 7(1): 3-15.   doi: 10.1016/j.gee.2020.12.023
[Abstract](642) [FullText HTML](297) [PDF 3992KB](47)
摘要:
In recent years, an increasing amount of interest has been dedicated to the synthesis and application of ZIF-67-based materials due to their exceptionally high surface area, tunable porosity, and excellent thermal and chemical stabilities. This review summarizes the latest strategies of synthesizing ZIF-67-based materials by exploring the prominent examples. Then, the recent progress in the applications of ZIF-67-based materials in heterogeneous catalysis, including catalysis of the redox reactions, addition reactions, esterification reactions, Knoevenagel condensations, and hydrogenation-dehydrogenation reactions, has been elaborately discussed. Finally, we end this work by shedding some light on the large-scale industrial production of ZIF-67-based materials and their applications in the future.
Lignin-based carbon fibers: Formation, modification and potential applications
Shichao Wang, Jixing Bai, Mugaanire Tendo Innocent, Qianqian Wang, Hengxue Xiang, Jianguo Tang, Meifang Zhu
2022, 7(4): 578-605.   doi: 10.1016/j.gee.2021.04.006
[Abstract](580) [FullText HTML](231) [PDF 7520KB](53)
摘要:
As an aromatic polymer in nature, lignin has recently attracted gross attention because of its advantages of high carbon content, low cost and bio-renewability. However, most lignin is directly burnt for power generation to satisfy the energy demand of the pulp mills. As a result, only a handful of isolated lignin is used as a raw material. Thus, increasing value addition on lignin to expand its scope of applications is currently a challenge demanding immediate attention. Many efforts have been made in the valorization of lignin, including the preparation of precursors for carbon fibers. However, its complex structure and diversity significantly restrict the spinnability of lignin. In this review, we provide elaborate knowledge on the preparation of lignin-based carbon fibers ranging from the relationships among chemical structures, formation conditions and properties of fibers, to their potential applications. Specifically, control procedures for different spinning methods of lignin, including melt spinning, solution spinning and electrospinning, together with stabilization and carbonization are deeply discussed to provide an overall understanding towards the formation of lignin-based carbon fibers. We also offer perspectives on the challenges and new directions for future development of lignin-based carbon fibers.
High piezo/photocatalytic efficiency of Ag/Bi5O7I nanocomposite using mechanical and solar energy for N2 fixation and methyl orange degradation
Lu Chen, Wenqian Zhang, Junfeng Wang, Xiaojing Li, Yi Li, Xin Hu, Leihong Zhao, Ying Wu, Yiming He
2023, 8(1): 283-295.   doi: 10.1016/j.gee.2021.04.009
[Abstract](385) [FullText HTML](168) [PDF 5433KB](33)
摘要:
In this work, Ag/Bi5O7I nanocomposite was prepared and firstly applied in piezo/photocatalytic reduction of N2 to NH3 and methyl orange (MO) degradation. Bi5O7I was synthesized via a hydrothermal-calcination method and shows nanorods morphology. Ag nanoparticles (NPs) were photo deposited on the Bi5O7I nanorods as electron trappers to improve the spatial separation of charge carriers, which was confirmed via XPS, TEM, and electronic chemical analyses. The catalytic test indicates that Bi5O7I presents the piezoelectric-like behavior, while the loading of Ag NPs can strengthen the character. Under ultrasonic vibration, the optimal Ag/Bi5O7I presents high efficiency in MO degradation. The degradation rate is determined to be 0.033 min-1, which is 4.7 folds faster than that of Bi5O7I. The Ag/Bi5O7I also presents a high performance in piezocatalytic N2 fixation. The piezocatalytic NH3 generation rate reaches 65.4 μmol L-1 g-1 h-1 with water as a hole scavenger. The addition of methanol can hasten the piezoelectric catalytic reaction. Interestingly, when ultrasonic vibration and light irradiation simultaneously act on the Ag/Bi5O7I catalyst, higher performance in NH3 generation and MO degradation is observed. However, due to the weak adhesion of Ag NPs, some Ag NPs would fall off from the Bi5O7I surface under long-term ultrasonic vibration, which would greatly reduce the piezoelectric catalytic performance. This result indicates that a strong binding force is required when preparing the piezoelectric composite catalyst. The current work provides new insights for the development of highly efficient catalysts that can use multiple energies.
Cell-free biocatalysis coupled with photo-catalysis and electro-catalysis: Efficient CO2-to-chemical conversion
Junzhu Yang, Chi-Kit Sou, Yuan Lu
2024, 9(9): 1366-1383.   doi: 10.1016/j.gee.2023.10.002
[Abstract](341) [PDF 4824KB](167)
Abstract:
The increasing atmospheric carbon dioxide (CO2) concentration has exposed a series of crises in the earth's ecological environment. How to effectively fix and convert carbon dioxide into products with added value has attracted the attention of many researchers. Cell-free enzyme catalytic system coupled with electrical and light have been a promising attempt in the field of biological carbon fixation in recent years. In this review, the research progresses of photoenzyme catalysis, electroenzyme catalysis and photo-electroenzyme catalysis for converting carbon dioxide into chemical products in cell-free systems are systematically summarized. We focus on reviewing and comparing various coupling methods and principles of photoenzyme catalysis and electroenzyme catalysis in cell-free systems, especially the materials used in the construction of the coupling system, and analyze and point out the characteristics and possible problems of different coupling methods. Finally, we discuss the major challenges and prospects of coupling physical signals and cell-free enzymatic catalytic systems in the field of CO2 fixation, suggesting possible strategies to improve the carbon sequestration capacity of such systems.
Spectrophotometric determination of the formation constants of Calcium(II) complexes with 1,2-ethylenediamine, 1,3-propanediamine and 1,4-butanediamine in acetonitrile
Jacqueline González González, Mónica Nájera-Lara, Varinia López-Ramírez, Juan Antonio Ramírez-Vázquez, José J.N. Segoviano-Garfias
2017, 2(1): 51-57.   doi: 10.1016/j.gee.2017.01.002
[Abstract](186) [FullText HTML](84) [PDF 1052KB](84)
Abstract:
In this work, with the purpose to explore the coordination chemistry of calcium complexes which could work as a partial model of manganese–calcium cluster, a spectrophotometric study to evaluate the stability of the complexes: Calcium(II)-1,2-ethylendiamine, Calcium(II)-1,3-propanediamine and Calcium(II)-1,4-butanediamine in acetonitrile, were carried on. By processing the spectrophotometric data with the HypSpec program allows the determination of the formation constants. The logarithmic values of the formation constants obtained for Calcium(II)-1,2-ethylendiamine, Calcium(II)-1,3-propanediamine and Calcium(II)-1,4-butanediamine were log β110 = 4.69, log β110 = 5.25 and log β110 = 4.072, respectively.
A comprehensive review on recent progress in aluminum–air batteries
Yisi Liu, Qian Sun, Wenzhang Li, Keegan R. Adair, Jie Li, Xueliang Sun
2017, 2(3): 246-277.   doi: 10.1016/j.gee.2017.06.006
[Abstract](853) [FullText HTML](389) [PDF 14207KB](389)
Abstract:
The aluminum–air battery is considered to be an attractive candidate as a power source for electric vehicles (EVs) because of its high theoretical energy density (8100 Wh kg−1), which is significantly greater than that of the state-of-the-art lithium-ion batteries (LIBs). However, some technical and scientific problems preventing the large-scale development of Al–air batteries have not yet to be resolved. In this review, we present the fundamentals, challenges and the recent advances in Al–air battery technology from aluminum anode, air cathode and electrocatalysts to electrolytes and inhibitors. Firstly, the alloying of aluminum with transition metal elements is reviewed and shown to reduce the self-corrosion of Al and improve battery performance. Additionally for the cathode, extensive studies of electrocatalytic materials for oxygen reduction/evolution including Pt and Pt alloys, nonprecious metal catalysts, and carbonaceous materials at the air cathode are highlighted. Moreover, for the electrolyte, the application of aqueous and nonaqueous electrolytes in Al–air batteries are discussed. Meanwhile, the addition of inhibitors to the electrolyte to enhance electrochemical performance is also explored. Finally, the challenges and future research directions are proposed for the further development of Al–air batteries.
Nitrogen-doping boosts *CO utilization and H2O activation on copper for improving CO2 reduction to C2+ products
Yisen Yang, Zhonghao Tan, Jianling Zhang, Jie Yang, Renjie Zhang, Sha Wang, Yi Song, Zhuizhui Su
2024, 9(9): 1459-1465.   doi: 10.1016/j.gee.2023.09.002
[Abstract](144) [PDF 1881KB](69)
Abstract:
To improve the electrocatalytic transformation of carbon dioxide (CO2) to multi-carbon (C2+) products is of great importance. Here we developed a nitrogen-doped Cu catalyst, by which the maximum C2+ Faradaic efficiency can reach 72.7% in flow-cell system, with the partial current density reaching 0.62 A cm-2. The in situ Raman spectra demonstrate that the *CO adsorption can be strengthened on such a N-doped Cu catalyst, thus promoting the *CO utilization in the subsequent C-C coupling step. Simultaneously, the water activation can be well enhanced by N doping on Cu catalyst. Owing to the synergistic effects, the selectivity and activity for C2+ products over the N-deoped Cu catalyst are much improved.
Recovery of greenhouse gas as cleaner fossil fuel contributes to carbon neutrality
Xin Zhang, Jian-Rong Li
2023, 8(2): 351-353.   doi: 10.1016/j.gee.2022.06.002
[Abstract](415) [PDF 438KB](171)
Abstract:
Under the context of carbon neutrality of China, it is urgent to shift our energy supply towards cleaner fuels as well as to reduce the greenhouse gas emission. Currently, coal is the main fossil fuel energy source of China. The country is striving hard to replace it with methane, a cleaner fossil fuel. Although China has rich geological resources of methane as coal bed methane (CBM) reserves, it is quite challenging to utilize them due to low concentration. The CBM is however mainly emitted directly to atmosphere during coal mining, causing waste of the resource and huge contribution to greenhouse effect. The recent work by Yang et al. demonstrated a potential solution to extract low concentration methane selectively from CBM through using MOF materials as sorbents. Such kind of materials and associated separation technology are promising to reduce greenhouse gas emission and promote the methane production capability, which would contribute to carbon neutrality in dual pathways.
Catalytic conversion of lignocellulosic biomass into chemicals and fuels
Weiping Deng, Yunchao Feng, Jie Fu, Haiwei Guo, Yong Guo, Buxing Han, Zhicheng Jiang, Lingzhao Kong, Changzhi Li, Haichao Liu, Phuc T.T. Nguyen, Puning Ren, Feng Wang, Shuai Wang, Yanqin Wang, Ye Wang, Sie Shing Wong, Kai Yan, Ning Yan, Xiaofei Yang, Yuanbao Zhang, Zhanrong Zhang, Xianhai Zeng, Hui Zhou
2023, 8(1): 10-114.   doi: 10.1016/j.gee.2022.07.003
Abstract HTML PDF
Abstract:
In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future, lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a promising feedstock. This review focuses on the state-of-the-art catalytic transformation of lignocellulosic biomass into value-added chemicals and fuels. Following a brief introduction on the structure, major resources and pretreatment methods of lignocellulosic biomass, the catalytic conversion of three main components, i.e., cellulose, hemicellulose and lignin, into various compounds are comprehensively discussed. Either in separate steps or in one-pot, cellulose and hemicellulose are hydrolyzed into sugars and upgraded into oxygen-containing chemicals such as 5-HMF, furfural, polyols, and organic acids, or even nitrogen-containing chemicals such as amino acids. On the other hand, lignin is first depolymerized into phenols, catechols, guaiacols, aldehydes and ketones, and then further transformed into hydrocarbon fuels, bioplastic precursors and bioactive compounds. The review then introduces the transformations of whole biomass via catalytic gasification, catalytic pyrolysis, as well as emerging strategies. Finally, opportunities, challenges and prospective of woody biomass valorization are highlighted.
Application of deep eutectic solvents in biomass pretreatment and conversion
Yu Chen, Tiancheng Mu
2019, 4(2): 95-115.   doi: 10.1016/j.gee.2019.01.012
Abstract HTML PDF
Abstract:
Biomass is renewable, abundant, cheap, biocompatible, and biodegradable materials and has been used to produce chemicals, materials, energy, and fuels. However, most of the biomass, especially most of the biomass polymers are not soluble in common solvents, which hinders their pretreatment and conversion. Deep eutectic solvents (DESs) are environmental-friendly, cheap, and highly tunable, with high solubility, which renders them potential applications in biomass pretreatment and conversion. They could be used as solvents or catalysts and so on. This paper intends to review the application of DESs for the pretreatment of biomass and conversion of biomass to value-added products. We focus on the following topics related to biomass and DESs: (1) DESs for the pretreatment of biomass; (2) DESs for the dissolution and separation of biomass or extraction of chemicals from biomass; (3) DESs for biomass conversion; (4) Drawbacks, and recyclability of DESs for pretreatment and conversion of biomass.
Synthesis and applications of MOF-derived porous nanostructures
Min Hui Yap, Kam Loon Fow, George Zheng Chen
2017, 2(3): 218-245.   doi: 10.1016/j.gee.2017.05.003
Abstract HTML PDF
Abstract:
Metal organic frameworks (MOFs) represent a class of porous material which is formed by strong bonds between metal ions and organic linkers. By careful selection of constituents, MOFs can exhibit very high surface area, large pore volume, and excellent chemical stability. Research on synthesis, structures and properties of various MOFs has shown that they are promising materials for many applications, such as energy storage, gas storage, heterogeneous catalysis and sensing. Apart from direct use, MOFs have also been used as support substrates for nanomaterials or as sacrificial templates/precursors for preparation of various functional nanostructures. In this review, we aim to present the most recent development of MOFs as precursors for the preparation of various nanostructures and their potential applications in energy-related devices and processes. Specifically, this present survey intends to push the boundaries and covers the literatures from the year 2013 to early 2017, on supercapacitors, lithium ion batteries, electrocatalysts, photocatalyst, gas sensing, water treatment, solar cells, and carbon dioxide capture. Finally, an outlook in terms of future challenges and potential prospects towards industrial applications are also discussed.
Overview of acidic deep eutectic solvents on synthesis, properties and applications
Hao Qin, Xutao Hu, Jingwen Wang, Hongye Cheng, Lifang Chen, Zhiwen Qi
2020, 5(1): 8-21.   doi: 10.1016/j.gee.2019.03.002
Abstract HTML PDF
Abstract:
This review divides the acidic deep eutectic solvents (ADES) into Brønsted and Lewis DES according to their diversity of acidic character. The hydrogen bond donors and halide salts for formulating an ADES are classified, the synthesis methods are described, and the physicochemical properties including freezing point, acidity, density, viscosity and conductivity are presented. Furthermore, the applications of Brønsted acidic deep eutectic solvents (BADES) and Lewis acidic deep eutectic solvents (LADES) are overviewed, respectively, covering the fields in dissolution, extraction, organic reaction and metal electrodeposition. It is expected that the ADES has great potential to replace the pollutional mineral acid, expensive and unstable solid acid, and costly ionic liquid in many acid-employed chemical processes, thus meeting the demands of green chemistry.
A comprehensive review on recent progress in aluminum–air batteries
Yisi Liu, Qian Sun, Wenzhang Li, Keegan R. Adair, Jie Li, Xueliang Sun
2017, 2(3): 246-277.   doi: 10.1016/j.gee.2017.06.006
Abstract HTML PDF
Abstract:
The aluminum–air battery is considered to be an attractive candidate as a power source for electric vehicles (EVs) because of its high theoretical energy density (8100 Wh kg−1), which is significantly greater than that of the state-of-the-art lithium-ion batteries (LIBs). However, some technical and scientific problems preventing the large-scale development of Al–air batteries have not yet to be resolved. In this review, we present the fundamentals, challenges and the recent advances in Al–air battery technology from aluminum anode, air cathode and electrocatalysts to electrolytes and inhibitors. Firstly, the alloying of aluminum with transition metal elements is reviewed and shown to reduce the self-corrosion of Al and improve battery performance. Additionally for the cathode, extensive studies of electrocatalytic materials for oxygen reduction/evolution including Pt and Pt alloys, nonprecious metal catalysts, and carbonaceous materials at the air cathode are highlighted. Moreover, for the electrolyte, the application of aqueous and nonaqueous electrolytes in Al–air batteries are discussed. Meanwhile, the addition of inhibitors to the electrolyte to enhance electrochemical performance is also explored. Finally, the challenges and future research directions are proposed for the further development of Al–air batteries.
Progress in aqueous rechargeable batteries
Jilei Liu, Chaohe Xu, Zhen Chen, Shibing Ni, Ze Xiang Shen
2018, 3(1): 20-41.   doi: 10.1016/j.gee.2017.10.001
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Abstract:
Over the past decades, a series of aqueous rechargeable batteries (ARBs) were explored, investigated and demonstrated. Among them, aqueous rechargeable alkali-metal ion (Li+, Na+, K+) batteries, aqueous rechargeable-metal ion (Zn2+, Mg2+, Ca2+, Al3+) batteries and aqueous rechargeable hybrid batteries are standing out due to peculiar properties. In this review, we focus on the fundamental basics of these batteries, and discuss the scientific and/or technological achievements and challenges. By critically reviewing state-of-the-art technologies and the most promising results so far, we aim to analyze the benefits of ARBs and the critical issues to be addressed, and to promote better development of ARBs.
Cellulose-based materials in wastewater treatment of petroleum industry
Baoliang Peng, Zhaoling Yao, Xiaocong Wang, Mitchel Crombeen, Dalton G. Sweeney, Kam Chiu Tam
2020, 5(1): 37-49.   doi: 10.1016/j.gee.2019.09.003
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The most abundant natural biopolymer on earth, cellulose fiber, may offer a highly efficient, low-cost, and chemical-free option for wastewater treatment. Cellulose is widely distributed in plants and several marine animals. It is a carbohydrate polymer consisting of β-1,4-linked anhydro-D-glucose units with three hydroxyl groups per anhydroglucose unit (AGU). Cellulose-based materials have been used in food, industrial, pharmaceutical, paper, textile production, and in wastewater treatment applications due to their low cost, renewability, biodegradability, and non-toxicity. For water treatment in the oil and gas industry, cellulose-based materials can be used as adsorbents, flocculants, and oil/water separation membranes. In this review, the uses of cellulose-based materials for wastewater treatment in the oil & gas industry are summarized, and recent research progress in the following aspects are highlighted: crude oil spill cleaning, flocculation of solid suspended matter in drilling or oil recovery in the upstream oil industry, adsorption of heavy metal or chemicals, and separation of oil/water by cellulosic membrane in the downstream water treatment.
Recent progress on synthesis of ZIF-67-based materials and their application to heterogeneous catalysis
Chongxiong Duan, Yi Yu, Han Hu
2022, 7(1): 3-15.   doi: 10.1016/j.gee.2020.12.023
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In recent years, an increasing amount of interest has been dedicated to the synthesis and application of ZIF-67-based materials due to their exceptionally high surface area, tunable porosity, and excellent thermal and chemical stabilities. This review summarizes the latest strategies of synthesizing ZIF-67-based materials by exploring the prominent examples. Then, the recent progress in the applications of ZIF-67-based materials in heterogeneous catalysis, including catalysis of the redox reactions, addition reactions, esterification reactions, Knoevenagel condensations, and hydrogenation-dehydrogenation reactions, has been elaborately discussed. Finally, we end this work by shedding some light on the large-scale industrial production of ZIF-67-based materials and their applications in the future.
Lignin-based carbon fibers: Formation, modification and potential applications
Shichao Wang, Jixing Bai, Mugaanire Tendo Innocent, Qianqian Wang, Hengxue Xiang, Jianguo Tang, Meifang Zhu
2022, 7(4): 578-605.   doi: 10.1016/j.gee.2021.04.006
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As an aromatic polymer in nature, lignin has recently attracted gross attention because of its advantages of high carbon content, low cost and bio-renewability. However, most lignin is directly burnt for power generation to satisfy the energy demand of the pulp mills. As a result, only a handful of isolated lignin is used as a raw material. Thus, increasing value addition on lignin to expand its scope of applications is currently a challenge demanding immediate attention. Many efforts have been made in the valorization of lignin, including the preparation of precursors for carbon fibers. However, its complex structure and diversity significantly restrict the spinnability of lignin. In this review, we provide elaborate knowledge on the preparation of lignin-based carbon fibers ranging from the relationships among chemical structures, formation conditions and properties of fibers, to their potential applications. Specifically, control procedures for different spinning methods of lignin, including melt spinning, solution spinning and electrospinning, together with stabilization and carbonization are deeply discussed to provide an overall understanding towards the formation of lignin-based carbon fibers. We also offer perspectives on the challenges and new directions for future development of lignin-based carbon fibers.
High piezo/photocatalytic efficiency of Ag/Bi5O7I nanocomposite using mechanical and solar energy for N2 fixation and methyl orange degradation
Lu Chen, Wenqian Zhang, Junfeng Wang, Xiaojing Li, Yi Li, Xin Hu, Leihong Zhao, Ying Wu, Yiming He
2023, 8(1): 283-295.   doi: 10.1016/j.gee.2021.04.009
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In this work, Ag/Bi5O7I nanocomposite was prepared and firstly applied in piezo/photocatalytic reduction of N2 to NH3 and methyl orange (MO) degradation. Bi5O7I was synthesized via a hydrothermal-calcination method and shows nanorods morphology. Ag nanoparticles (NPs) were photo deposited on the Bi5O7I nanorods as electron trappers to improve the spatial separation of charge carriers, which was confirmed via XPS, TEM, and electronic chemical analyses. The catalytic test indicates that Bi5O7I presents the piezoelectric-like behavior, while the loading of Ag NPs can strengthen the character. Under ultrasonic vibration, the optimal Ag/Bi5O7I presents high efficiency in MO degradation. The degradation rate is determined to be 0.033 min-1, which is 4.7 folds faster than that of Bi5O7I. The Ag/Bi5O7I also presents a high performance in piezocatalytic N2 fixation. The piezocatalytic NH3 generation rate reaches 65.4 μmol L-1 g-1 h-1 with water as a hole scavenger. The addition of methanol can hasten the piezoelectric catalytic reaction. Interestingly, when ultrasonic vibration and light irradiation simultaneously act on the Ag/Bi5O7I catalyst, higher performance in NH3 generation and MO degradation is observed. However, due to the weak adhesion of Ag NPs, some Ag NPs would fall off from the Bi5O7I surface under long-term ultrasonic vibration, which would greatly reduce the piezoelectric catalytic performance. This result indicates that a strong binding force is required when preparing the piezoelectric composite catalyst. The current work provides new insights for the development of highly efficient catalysts that can use multiple energies.
Cell-free biocatalysis coupled with photo-catalysis and electro-catalysis: Efficient CO2-to-chemical conversion
Junzhu Yang, Chi-Kit Sou, Yuan Lu
2024, 9(9): 1366-1383.   doi: 10.1016/j.gee.2023.10.002
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The increasing atmospheric carbon dioxide (CO2) concentration has exposed a series of crises in the earth's ecological environment. How to effectively fix and convert carbon dioxide into products with added value has attracted the attention of many researchers. Cell-free enzyme catalytic system coupled with electrical and light have been a promising attempt in the field of biological carbon fixation in recent years. In this review, the research progresses of photoenzyme catalysis, electroenzyme catalysis and photo-electroenzyme catalysis for converting carbon dioxide into chemical products in cell-free systems are systematically summarized. We focus on reviewing and comparing various coupling methods and principles of photoenzyme catalysis and electroenzyme catalysis in cell-free systems, especially the materials used in the construction of the coupling system, and analyze and point out the characteristics and possible problems of different coupling methods. Finally, we discuss the major challenges and prospects of coupling physical signals and cell-free enzymatic catalytic systems in the field of CO2 fixation, suggesting possible strategies to improve the carbon sequestration capacity of such systems.
Spectrophotometric determination of the formation constants of Calcium(II) complexes with 1,2-ethylenediamine, 1,3-propanediamine and 1,4-butanediamine in acetonitrile
Jacqueline González González, Mónica Nájera-Lara, Varinia López-Ramírez, Juan Antonio Ramírez-Vázquez, José J.N. Segoviano-Garfias
2017, 2(1): 51-57.   doi: 10.1016/j.gee.2017.01.002
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In this work, with the purpose to explore the coordination chemistry of calcium complexes which could work as a partial model of manganese–calcium cluster, a spectrophotometric study to evaluate the stability of the complexes: Calcium(II)-1,2-ethylendiamine, Calcium(II)-1,3-propanediamine and Calcium(II)-1,4-butanediamine in acetonitrile, were carried on. By processing the spectrophotometric data with the HypSpec program allows the determination of the formation constants. The logarithmic values of the formation constants obtained for Calcium(II)-1,2-ethylendiamine, Calcium(II)-1,3-propanediamine and Calcium(II)-1,4-butanediamine were log β110 = 4.69, log β110 = 5.25 and log β110 = 4.072, respectively.
A comprehensive review on recent progress in aluminum–air batteries
Yisi Liu, Qian Sun, Wenzhang Li, Keegan R. Adair, Jie Li, Xueliang Sun
2017, 2(3): 246-277.   doi: 10.1016/j.gee.2017.06.006
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The aluminum–air battery is considered to be an attractive candidate as a power source for electric vehicles (EVs) because of its high theoretical energy density (8100 Wh kg−1), which is significantly greater than that of the state-of-the-art lithium-ion batteries (LIBs). However, some technical and scientific problems preventing the large-scale development of Al–air batteries have not yet to be resolved. In this review, we present the fundamentals, challenges and the recent advances in Al–air battery technology from aluminum anode, air cathode and electrocatalysts to electrolytes and inhibitors. Firstly, the alloying of aluminum with transition metal elements is reviewed and shown to reduce the self-corrosion of Al and improve battery performance. Additionally for the cathode, extensive studies of electrocatalytic materials for oxygen reduction/evolution including Pt and Pt alloys, nonprecious metal catalysts, and carbonaceous materials at the air cathode are highlighted. Moreover, for the electrolyte, the application of aqueous and nonaqueous electrolytes in Al–air batteries are discussed. Meanwhile, the addition of inhibitors to the electrolyte to enhance electrochemical performance is also explored. Finally, the challenges and future research directions are proposed for the further development of Al–air batteries.
Nitrogen-doping boosts *CO utilization and H2O activation on copper for improving CO2 reduction to C2+ products
Yisen Yang, Zhonghao Tan, Jianling Zhang, Jie Yang, Renjie Zhang, Sha Wang, Yi Song, Zhuizhui Su
2024, 9(9): 1459-1465.   doi: 10.1016/j.gee.2023.09.002
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To improve the electrocatalytic transformation of carbon dioxide (CO2) to multi-carbon (C2+) products is of great importance. Here we developed a nitrogen-doped Cu catalyst, by which the maximum C2+ Faradaic efficiency can reach 72.7% in flow-cell system, with the partial current density reaching 0.62 A cm-2. The in situ Raman spectra demonstrate that the *CO adsorption can be strengthened on such a N-doped Cu catalyst, thus promoting the *CO utilization in the subsequent C-C coupling step. Simultaneously, the water activation can be well enhanced by N doping on Cu catalyst. Owing to the synergistic effects, the selectivity and activity for C2+ products over the N-deoped Cu catalyst are much improved.
Recovery of greenhouse gas as cleaner fossil fuel contributes to carbon neutrality
Xin Zhang, Jian-Rong Li
2023, 8(2): 351-353.   doi: 10.1016/j.gee.2022.06.002
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Under the context of carbon neutrality of China, it is urgent to shift our energy supply towards cleaner fuels as well as to reduce the greenhouse gas emission. Currently, coal is the main fossil fuel energy source of China. The country is striving hard to replace it with methane, a cleaner fossil fuel. Although China has rich geological resources of methane as coal bed methane (CBM) reserves, it is quite challenging to utilize them due to low concentration. The CBM is however mainly emitted directly to atmosphere during coal mining, causing waste of the resource and huge contribution to greenhouse effect. The recent work by Yang et al. demonstrated a potential solution to extract low concentration methane selectively from CBM through using MOF materials as sorbents. Such kind of materials and associated separation technology are promising to reduce greenhouse gas emission and promote the methane production capability, which would contribute to carbon neutrality in dual pathways.

Editor-in-Chief:Buxing Han

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