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Rare earth metal-organic framework catalysts: properties, synthesis, characterizations, and application
Liming Wang, Shunzheng Zhao, Xiaolong Tang, Qingjun Yu, Fengyu Gao, Huiting Ming, Qiyu Li, Honghong Yi
 doi: 10.1016/j.gee.2026.03.003
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Abstract:
Among numerous metal-organic frameworks, rare earth metal-organic frameworks (RE-MOFs) have garnered significant attention across various catalytic fields. As a special class of MOFs, they exhibit high and tunable coordination numbers, diverse crystal structures, strong Lewis acidity, and excellent optical behavior—properties intrinsically linked to their outstanding catalytic performance. This paper presents a comprehensive review of RE-MOFs in catalysis, focusing on their synthesis and modification strategies, advanced characterization techniques, and specific applications. Solvothermal synthesis remains the prevalent method for preparing RE-MOFs, though more environmentally friendly approaches have emerged in recent years. Defect engineering enhances active sites and porosity, doping alters coordination types between organic ligands and metal ions, while MOF-on-MOF structures induce internal charge redistribution and electronic structure modifications—all effective strategies for boosting catalytic activity. Different characterization techniques are required to investigate the oxidation states of rare earth elements and the MOF structures. We list several key characterization methods that best demonstrate their features. Finally, this paper comprehensively summarizes the active sites provided by RE-MOFs and their catalytic principles across various reactions in fields such as energy conversion, environmental remediation, and organic chemistry. This review aims to provide theoretical guidance for designing highly efficient RE-MOF catalysts.
Cellulose Nanofiber-Based Nanofiltration Membranes for Sustainable Water Purification
Ge Li, Xinchen Xiang, Yunlong Cui, Xiaolu Ni, Kailun Zou, Guozhong Shi, Zhikan Yao, Lin Zhang
 doi: 10.1016/j.gee.2026.03.006
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Abstract:
Although nanofiltration (NF) membranes enable energy-efficient molecular separations critical for sustainable ecosystem, their conventional fabrication from petrochemical polymers raises end-of-life environmental concerns. Cellulose nanofiber (CNF), as a biodegradable and renewable biomass material, offers a promising green alternative for NF membrane production. However, fabricating dense NF membranes from highly concentrated CNF suspensions remains challenging due to their high viscosity and poor film-forming properties. In this work, we overcame these limitations through an acidification-assisted process that disrupts the CNF gel network, enabling improved processability. Subsequent crosslinking with glutaraldehyde and thermal-induced formation yielded a robust and dense NF membrane with tailored nanostructure. The optimized membrane exhibited effective separation performance, achieving approximately 90% rejection of Na2SO4 and 99.4% removal of humic acid while maintaining a water flux over 20 L·m-2·h-1. This work proposes a sustainable fabrication route for high-performance nanocellulose membranes, establishing a renewable alternative to conventional petrochemical-based water purification filtration materials.
Synergistic design of O2/O3 composite Li-rich cathodes: A novel strategy for high-performance Li-ion batteries
Wangwei Ren, Qiang Lu, Dezhi Yan, Shichao Zhang, Puheng Yang, Zhe Zhang, Feiyue Zhai, Shuai Yin, Yiyuan Yan, Shen Liu, Guowei Liao, Qianfan Zhang, Xingjiang Liu, Yalan Xing
 doi: 10.1016/j.gee.2026.03.005
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Abstract:
Due to their unique anion and cation redox mechanisms, Li-rich Mn-based layered oxide cathodes are considered extremely promising candidates for next-generation high-performance Li-ion batteries. However, their practical applications are limited by capacity degradation, voltage degradation, and poor rate performance. In this work, an O2/O3 composite Li-rich cathode was constructed by integrating nanoscale O3 particles on the surface of O2 microspheres. By combining the inherent excellent voltage retention of the O2-type structure with the nanostructured O3 rate advantage, the O2/O3 composite cathodes exhibit excellent specific capacity, cycling stability, and rate performance. Thanks to the synergistic effect of O2 and O3, the obtained composite cathode has a high discharge specific capacity of 298.06 mAh g-1 at 0.1C. It maintains 85.34% capacity retention after 100 cycles at 0.5C and still delivers a discharge specific capacity of 144.64 mAh g-1 at 5C. Based on experiments and theoretical calculations, the potential impact of the O2/O3 interface on electrochemical performance is elucidated. The built-in electric field at the two-phase interface plays a crucial role in structural stability. The O2/O3 composite cathode developed in this study holds potential to advance the development of high-performance Li-ion batteries.
Biomass-engineered graphitic carbon nitride: structure modulation, charge dynamics, and photocatalytic applications
Yuan Xue, Sheng Liu, Yujuan Guo, Yanjun Zhang, Zushun Xu, Yongxing Zhang, Guangfu Liao, Qing Li
 doi: 10.1016/j.gee.2026.03.002
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Abstract:
Graphitic carbon nitride (g-C3N4) is a metal-free, environmentally sustainable semiconductor photocatalyst characterized by its well-defined layered structure, tunable electronic structure, and exceptional optical properties. To address the inherent limitations of g-C3N4 that impede its practical application and development, researchers have devised diverse modification strategies, spanning nanostructure engineering, elemental doping/defect introduction, and heterojunction construction. This review underscores the multifaceted synergistic effects derived from the structural diversity of biomass during modification processes. These integrate three core components: (i) Utilizing the unique chiral architecture and abundant functional groups for morphological control (ii) Band structure engineering through biomass-derived unique skeletons and multi-element induced defect formation and (iii) Constructing heterojunctions with unique interfacial effects by integrating biomass materials of different dimensional architectures. Furthermore, synergistic modifications enable atomic-scale lattice engineering with capabilities beyond those achievable by traditional inorganic precursors. Subsequently, we also introduce the applications of biomass-derived modifications in regulating g-C3N4 photocatalysts toward addressing energy conversion and environmental remediation challenges. Finally, we delineate the promising trajectory of biomass-engineered g-C3N4 photocatalysts, envisioning their expanded deployment in energy conversion systems through synergistic integration with emerging technologies.
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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](2161) [PDF 23019KB](156)
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.
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](1288) [FullText HTML](576) [PDF 1576KB](141)
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.
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](1225) [FullText HTML](556) [PDF 3331KB](148)
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](986) [FullText HTML](410) [PDF 6267KB](113)
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.
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](1757) [FullText HTML](762) [PDF 14207KB](221)
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](636) [FullText HTML](273) [PDF 6967KB](84)
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.
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](1213) [FullText HTML](570) [PDF 3992KB](92)
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.
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](637) [FullText HTML](297) [PDF 2482KB](72)
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.
A survey of hybrid energy devices based on supercapacitors
Dan Gao, Zhiling Luo, Changhong Liu, Shoushan Fan
2023, 8(4): 972-988.   doi: 10.1016/j.gee.2022.02.002
[Abstract](513) [PDF 5056KB](35)
摘要:
Developing multifunctional energy storage systems with high specific energy, high specific power and long cycling life has been the one of the most important research directions. Compared to batteries and traditional capacitors, supercapacitors possess more balanced performance with both high specific power and long cycle-life. Nevertheless, regular supercapacitors can only achieve energy storage without harvesting energy and the energy density is still not very high compared to batteries. Therefore, combining high specific energy and high specific power, long cycle-life and even fast self-charging into one cell has been a promising direction for future energy storage devices. The multifunctional hybrid supercapacitors like asymmetric supercapacitors, batteries/supercapacitors hybrid devices and self-charging hybrid supercapacitors have been widely studied recently. Carbon based electrodes are common materials used in all kinds of energy storage devices due to their fabulous electrical and mechanical properties. In this survey, the research progress of all kinds of hybrid supercapacitors using multiple effects and their working mechanisms are briefly reviewed. And their advantages and disadvantages are discussed. The hybrid supercapacitors have great application potential for portable electronics, wearable devices and implantable devices 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](980) [FullText HTML](426) [PDF 7520KB](75)
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.
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](529) [PDF 4824KB](259)
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.
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](1757) [FullText HTML](762) [PDF 14207KB](762)
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.
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](308) [FullText HTML](167) [PDF 1052KB](167)
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.
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](274) [PDF 1881KB](136)
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](658) [PDF 438KB](293)
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.
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.
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.
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
Abstract HTML PDF
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.
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.
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.
A survey of hybrid energy devices based on supercapacitors
Dan Gao, Zhiling Luo, Changhong Liu, Shoushan Fan
2023, 8(4): 972-988.   doi: 10.1016/j.gee.2022.02.002
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Developing multifunctional energy storage systems with high specific energy, high specific power and long cycling life has been the one of the most important research directions. Compared to batteries and traditional capacitors, supercapacitors possess more balanced performance with both high specific power and long cycle-life. Nevertheless, regular supercapacitors can only achieve energy storage without harvesting energy and the energy density is still not very high compared to batteries. Therefore, combining high specific energy and high specific power, long cycle-life and even fast self-charging into one cell has been a promising direction for future energy storage devices. The multifunctional hybrid supercapacitors like asymmetric supercapacitors, batteries/supercapacitors hybrid devices and self-charging hybrid supercapacitors have been widely studied recently. Carbon based electrodes are common materials used in all kinds of energy storage devices due to their fabulous electrical and mechanical properties. In this survey, the research progress of all kinds of hybrid supercapacitors using multiple effects and their working mechanisms are briefly reviewed. And their advantages and disadvantages are discussed. The hybrid supercapacitors have great application potential for portable electronics, wearable devices and implantable devices 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.
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.
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.
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.
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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