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The advantageous active sites construction and the electronic structure modification of cobalt-modified CeO2 for efficient solar-driven CO2 reduction
Xianxian Yang, Yixuan Hu, Jinman Yang, Haoyuan Yin, Yansheng Du, Minqiang He, Xiaojie She, Yanhua Song, Xingwang Zhu, Hui Xu
 doi: 10.1016/j.gee.2026.04.002
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Abstract:
Converting CO2 into high-value-added products through photocatalytic technology is an effective approach to addressing the greenhouse effect and alleviating the energy crisis at present. In this paper, Co-doped CeO2 was successfully prepared using the oil bath plus calcination method to achieve efficient photocatalytic reduction of CO2. The introduction of Co provides advantageous active sites for the photocatalytic CO2 reduction reaction system, enhancing the adsorption of CO2 molecules. Meanwhile, DFT calculations show that the introduction of Co can efficiently regulate the charge distribution to achieve electron localization, enhancing the activation of CO2 molecules. Additionally, it can accelerate the separation and transfer of photogenerated carriers, significantly improving the photocatalytic activity of CO2 reduction. The CO yield of Co/CeO2 is 19.50 μmol g-1 h-1, which is 12 times that of the CeO2 monomer, and this catalyst has good stability. This research provides a new idea for doping metal oxides with metal elements for the efficient reduction of CO2 in photocatalysis.
Robust interfacial layer stabilizing phase transition of high-voltage spinel cathode
Bokun Zhang, Yan Li, Jiguo Tu, Jing Wang, Xiaocui Xie, Shuqiang Jiao
 doi: 10.1016/j.gee.2026.04.003
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Abstract:
High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) stands out as a promising candidate for next-generation high-performance lithium-ion batteries, offering high energy density and cost advantages. Nevertheless, its practical application is hindered by critical challenges, such as surface instability and detrimental side reactions with electrolytes at high voltages, which lead to rapid capacity fading. Herein, an ultrathin, dense LiF interfacial layer (~2 nm) is successfully constructed on the surface of the truncated octahedral LNMO particles (F-LNMO) via a facile fluorination approach. This modification strategy effectively suppresses lattice oxygen loss and direct interaction between the electrolyte and highly reactive Ni/Mn species, drives the critical shift in the Li1 → Li0.5 phase transition pathway from a two-phase reaction to a more stable solid-solution reaction, and triggers the formation of the dense and uniform cathodeelectrolyte interphase (CEI) layer during cycling, thereby reducing transition metal dissolution. The as-prepared F-LNMO material demonstrates exceptional cycling stability, with a remarkable capacity retention of 92.7% after 300 cycles, and improved ion diffusion coefficient of 8.92 × 10-10 cm2 s-1. These findings highlight the critical role of artificial interfacial engineering in optimizing high-energy-density LNMO cathode materials with improved stability and rate performance.
Potential High-Performance Electrodes of Mn-Based Materials for Aqueous Zinc-ion Battery: from Material Design to Mechanism Study
Siying Wang, Yidi Liu, Haiding Zhu, Xuefeng Ren, Anmin Liu, Xifei Li, Chong Peng
 doi: 10.1016/j.gee.2026.03.024
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Abstract:
To address the energy crisis and environmental pollution caused by the use of fossil fuels, there is an urgent need for rechargeable energy storage devices. Among them, aqueous zinc-ion batteries (ZIBs) have gained significant attention as a promising energy storage solution due to their cost-effectiveness, safety, and high performance. However, the search for suitable cathode materials to enhance the energy and power density of aqueous zinc-ion batteries is still ongoing. This review provides a detailed summary of recent advancements in Mn-based materials as cathode materials for ZIBs, with a focus on the energy storage mechanisms of Mn-based materials. It highlights current research efforts on modification strategies, including pre-intercalation strategies, defect engineering, construction of composite materials, and structural and architectural design of manganese compounds. By further subdividing these modification approaches, the review aims to provide a deeper understanding of the development status of Mn-based materials. Additionally, the limitations and future prospects of Mn-based materials for ZIBs are discussed. This study aims to offer guidance for the design of high-performance Mn-based materials and inspire further innovation in ZIBs research.
Engineered Mo-O-Fe active centers for Efficient and Stable Overall Water Splitting along the Lattice-Oxygen Mechanism
Jinqiu Shi, Min Wang, Luwei Peng, Xi Luo, Jiajun Meng, Jianfeng Xu, Jinli Qiao
 doi: 10.1016/j.gee.2026.03.015
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Abstract:
The covalency of the metal-oxygen (M-O) bond is significantly enhanced in the transition metal sites with high oxidation states, thereby enabling the lattice oxygen-mediated mechanism (LOM) to break the traditional linear scaling limitations of the oxygen evolution reaction (OER). Here, an innovative MoO2 surface is designed to adjust the covalency of Fe-O bond in NiFe layered double hydroxide (NiFe-LDH), which results in the formation of Fe-O-Mo bridge with high valence Fe species for OER along the LOM. The MoO2-modified NiFe-LDH anchored on nickel foam, shows a 3D nanoflower-like heterostructure of interwoven porous nanosheets, which exposes abundant active sites, boosts charge transfer, and modulates the reaction microenvironment via heterojunction and confinement effects. This designed architecture shows excellent bifunctional catalytic activity, manifested by low overpotentials for HER (131 mV) and OER (226 mV) at 10 mA cm-2, respectively. The overall water electrolyzer verifies the device-level application potential assembled with MoO2/NiFe-LDH@NF as both cathode and anode, and achieves a low cell voltage of 1.650 V at 0.5 A cm-2 and stable operation for over 700 hours.
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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](2331) [PDF 23019KB](160)
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](1404) [FullText HTML](630) [PDF 1576KB](145)
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](1366) [FullText HTML](628) [PDF 3331KB](153)
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.
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](1957) [FullText HTML](845) [PDF 14207KB](224)
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.
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](1094) [FullText HTML](463) [PDF 6267KB](114)
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.
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](720) [FullText HTML](314) [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](1396) [FullText HTML](658) [PDF 3992KB](103)
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](681) [FullText HTML](319) [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](603) [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](1121) [FullText HTML](489) [PDF 7520KB](81)
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](555) [PDF 4824KB](270)
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](1957) [FullText HTML](845) [PDF 14207KB](845)
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](326) [FullText HTML](175) [PDF 1052KB](175)
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](304) [PDF 1881KB](152)
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](698) [PDF 438KB](313)
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.
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.
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.
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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Abstract:
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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