2023 Vol. 8, No. 3

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Towards a molecular understanding of the electronic metal-support interaction (EMSI) in heterogeneous catalysis
Keng Sang, Ji Zuo, Xiangxue Zhang, Qianhong Wang, Wenyao Chen, Gang Qian, Xuezhi Duan
2023, 8(3): 619-625. doi: 10.1016/j.gee.2022.12.006
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Tailoring the electronic metal-support interaction (EMSI) has attracted considerable interests as one of the most efficient approaches to improve both the activity and stability of metal catalysts in heterogeneous catalysis. In this viewpoint, we illustrate the methodology and relevant fundamentals on the disentanglement, characterization, and interpretation of EMSI. Under the choice of monometallic catalyst over inert support, a combination of optimal experiment design, multimodal techniques, in situ characterization, with a comprehensive understanding of the underlying measurement protocols is highly desirable for a reliable determination of EMSI. Accordingly, not only the d-band filling but also d-band energy within the EMSI should be taken into consideration for providing general principles to guide the electron-promoting catalytic reaction.
Review article
Advances of manganese-oxides-based catalysts for indoor formaldehyde removal
Jiayu Zheng, Wenkang Zhao, Liyun Song, Hao Wang, Hui Yan, Ge Chen, Changbao Han, Jiujun Zhang
2023, 8(3): 626-653. doi: 10.1016/j.gee.2022.01.008
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Formaldehyde (HCHO) has been identified as one of the most common indoor pollutions nowadays. Manganese oxides (MnO) are considered to be a promising catalytic material used in indoor HCHO oxidation removal due to their high catalytic activity, low-cost, and environmentally friendly. In this paper, the progress in developing MnO-based catalysts for HCHO removal is comprehensively reviewed for exploring the mechanisms of catalytic oxidation and catalytic deactivation. The catalytic oxidation mechanisms based on three typical theory models (Mars-van-Krevelen, Eley-Rideal and Langmuir-Hinshelwood) are discussed and summarized. Furthermore, the research status of catalytic deactivation, catalysts’ regeneration and integrated application of MnO-based catalysts for indoor HCHO removal are detailed in the review. Finally, the technical challenges in developing MnO-based catalysts for indoor HCHO removal are analyzed and the possible research direction is also proposed for overcoming the challenges toward practical application of such catalysts.
Recent advancement and future challenges of photothermal catalysis for VOCs elimination: From catalyst design to applications
Yang Yang, Shenghao Zhao, Lifeng Cui, Fukun Bi, Yining Zhang, Ning Liu, Yuxin Wang, Fudong Liu, Chi He, Xiaodong Zhang
2023, 8(3): 654-672. doi: 10.1016/j.gee.2022.02.006
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Photothermal catalysis realizes the synergistic effect of solar energy and thermochemistry, which also has the potential to improve the reaction rate and optimize the selectivity. In this review, the research progress of photothermal catalytic removal of volatile organic compounds (VOCs) by nano-catalysts in recent years is systematically reviewed. First, the fundamentals of photothermal catalysis and the fabrication of catalysts are described, and the design strategy of optimizing photothermal catalysis performance is proposed. Second, the performance for VOC degradation with photothermal catalysis is evaluated and compared for the batch and continuous systems. Particularly, the catalytic mechanism of VOC oxidation is systematically introduced based on experimental and theoretical study. Finally, the future limitations and challenges have been discussed, and potential research directions and priorities are highlighted. A broad view of recent photothermal catalyst fabrication, applications, challenges, and prospects can be systemically provided by this review.
Advances in particulate matter filtration: Materials, performance, and application
Xuzheng Ji, Jianying Huang, Lin Teng, Shuhui Li, Xiao Li, Weilong Cai, Zhong Chen, Yuekun Lai
2023, 8(3): 673-697. doi: 10.1016/j.gee.2022.03.012
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Air-borne pollutants in particulate matter (PM) form, produced either physically during industrial processes or certain biological routes, have posed a great threat to human health. Particularly during the current COVID-19 pandemic, effective filtration of the virus is an urgent matter worldwide. In this review, we first introduce some fundamentals about PM, including its source and classification, filtration mechanisms, and evaluation parameters. Advanced filtration materials and their functions are then summarized, among which polymers and MOFs are discussed in detail together with their antibacterial performance. The discussion on the application is divided into end-of-pipe treatment and source control. Finally, we conclude this review with our prospective view on future research in this area.
Application of metal organic framework in wastewater treatment
Xiaoge Liu, Yuying Shan, Songtao Zhang, Qingquan Kong, Huan Pang
2023, 8(3): 698-721. doi: 10.1016/j.gee.2022.03.005
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Water pollution is an increasingly serious environmental problem because many pollutants have carcinogenic effects on humans and aquatic organisms. Metal organic framework (MOF), made up of metal ions and multifunctional organic ligands, has been one of the most concerned materials because of its adjustable and regular pore structure. MOFs have always shown attractive advantages in membrane separation and adsorption technologies, among which water-stable MOFs are particularly prominent in wastewater treatment (WWT) applications. This review systematically summarizes the application of MOF membranes in membrane filtration, membrane pervaporation and membrane distillation. Also, the adsorption mechanisms of heavy metals, dyes and antibacterials in wastewater have been concluded. In order to tap the full application potential of pristine MOFs in sustainable wastewater treatment, current challenges are discussed in detail and future research directions are proposed.
Tuning the selectivity of natural oils and fatty acids/esters deoxygenation to biofuels and fatty alcohols: A review
Yingdong Zhou, Javier Remón, Zhicheng Jiang, Avtar S. Matharu, Changwei Hu
2023, 8(3): 722-743. doi: 10.1016/j.gee.2022.03.001
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The chemical transformation of natural oils provides alternatives to limited fossil fuels and produces compounds with added value for the chemical industries. The selective deoxygenation of natural oils to diesel-ranged hydrocarbons, bio-jet fuels, or fatty alcohols with controllable selectivity is especially attractive in natural oil feedstock biorefineries. This review presents recent progress in catalytic deoxygenation of natural oils or related model compounds (e.g., fatty acids) to renewable liquid fuels (green diesel and bio-jet fuels) and valuable fatty alcohols (unsaturated and saturated fatty alcohols). Besides, it discusses and compares the existing and potential strategies to control the product selectivity over heterogeneous catalysts. Most research conducted and reviewed has only addressed the production of one category; therefore, a new integrative vision exploring how to direct the process toward fuel and/or chemicals is urgently needed. Thus, work conducted to date addressing the development of new catalysts and studying the influence of the reaction parameters (e.g., temperature, time and hydrogen pressure) is summarized and critically discussed from a green and sustainable perspective using efficiency indicators (e.g., yields, selectivity, turnover frequencies and catalysts lifetime). Special attention has been given to the chemical transformations occurring to identify key descriptors to tune the selectivity toward target products by manipulating the reaction conditions and the structures of the catalysts. Finally, the challenges and future research goals to develop novel and holistic natural oil biorefineries are proposed. As a result, this critical review provides the readership with appropriate information to selectively control the transformation of natural oils into either biofuels and/or value-added chemicals. This new flexible vision can help pave the wave to suit the present and future market needs.
Research paper
Are Ni/ and Ni5Fe1/biochar catalysts suitable for synthetic natural gas production? A comparison with γ-Al2O3 supported catalysts
M. González-Castaño, C. Morales, J. C. Navarro de Miguel, J. H. Boelte, O. Klepel, J. I. Flege, H. Arellano-García
2023, 8(3): 744-756. doi: 10.1016/j.gee.2021.05.007
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Among challenges implicit in the transition to the post-fossil fuel energetic model, the finite amount of resources available for the technological implementation of CO2 revalorizing processes arises as a central issue. The development of fully renewable catalytic systems with easier metal recovery strategies would promote the viability and sustainability of synthetic natural gas production circular routes. Taking Ni and NiFe catalysts supported over γ-Al2O3 oxide as reference materials, this work evaluates the potentiality of Ni and NiFe supported biochar catalysts for CO2 methanation. The development of competitive biochar catalysts was found dependent on the creation of basic sites on the catalyst surface. Displaying lower Turn Over Frequencies than Ni/Al catalyst, the absence of basic sites achieved over Ni/C catalyst was related to the depleted catalyst performances. For NiFe catalysts, analogous Ni5Fe1 alloys were constituted over both alumina and biochar supports. The highest specific activity of the catalyst series, exhibited by the NiFe/C catalyst, was related to the development of surface basic sites along with weaker NiFe-C interactions, which resulted in increased Ni0:NiO surface populations under reaction conditions. In summary, the present work establishes biochar supports as a competitive material to consider within the future low-carbon energetic panorama.
Aluminum-air battery with cotton substrate: Controlling the discharge capacity by electrolyte pre-deposition
Wending Pan, Yifei Wang, Holly Y. H. Kwok, Dennis Y. C. Leung
2023, 8(3): 757-766. doi: 10.1016/j.gee.2021.05.003
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Conventional Al-air battery has many disadvantages for miniwatt applications, such as the complex water management, bulky electrolyte storage and potential leakage hazard. Moreover, the self-corrosion of Al anode continues even when the electrolyte flow is stopped, leading to great Al waste. To tackle these issues, an innovative cotton-based aluminum-air battery is developed in this study. Instead of flowing alkaline solution, cotton substrate pre-deposited with solid alkaline is used, together with a small water reservoir to continuously wet the cotton and dissolve the alkaline in-situ. In this manner, the battery can be mechanically recharged by replacing the cotton substrate and refilling the water reservoir, while the thick aluminum anode can be reused for tens of times until complete consumption. The cotton substrate shows excellent ability for the storage and transportation of alkaline electrolyte, leading to a high peak power density of 73 mW cm-2 and a high specific energy of 930 mW h g-1. Moreover, the battery discharge capacity is found to be linear to the loading of pre-deposited alkaline, so that it can be precisely controlled according to the mission profile to avoid Al waste. Finally, a two-cell battery pack with common water reservoir is developed, which can provide a voltage of 2.7 V and a power output of 223.8 mW. With further scaling-up and stacking, this cotton-based Al-air battery system with low cost and high energy density is very promising for recharging miniwatt electronics in the outdoor environment.
Novel in-capsule synthesis of metal-organic framework for innovative carbon dioxide capture system
Wei Yu, Ming Gao, Guanhe Rim, Tony G. Feric, Mark L. Rivers, Ammar Alahmed, Aqil Jamal, Ah-Hyung Alissa Park
2023, 8(3): 767-774. doi: 10.1016/j.gee.2021.08.002
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Metal-Organic Frameworks (MOFs) have been developed as solid sorbents for CO2 capture applications and their properties can be controlled by tuning the chemical blocks of their crystalline units. A number of MOFs (e.g., HKUST-1) have been developed but the question remains how to deploy them for gas-solid contact. Unfortunately, the direct use of MOFs as nanocrystals would lead to serious problems and risks. Here, for the first time, we report a novel MOF-based hybrid sorbent that is produced via an innovative in-situ microencapsulated synthesis. Using a custom-made double capillary microfluidic assembly, double emulsions of the MOF precursor solutions and UV-curable silicone shell fluid are produced. Subsequently, HKUST-1 MOF is successfully synthesized within the droplets enclosed in the gas permeable microcapsules. The developed MOF-bearing microcapsules uniquely allow the deployment of functional nanocrystals without the challenge of handling ultrafine particles, and further, can selectively reject undesired compounds to protect encapsulated MOFs.
A purely green approach to low-cost mass production of zeolitic imidazolate frameworks
Hai Li, Wan Chen, Bei Liu, Mingke Yang, Zixuan Huang, Changyu Sun, Chun Deng, Dapeng Cao, Guangjin Chen
2023, 8(3): 775-784. doi: 10.1016/j.gee.2021.09.003
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Although zeolitic imidazolate frameworks (ZIFs) have bright prospects in wide fields like gas storage/separation, catalysis and medicine, etc., their large-scale applications are bottlenecked by the absence of their low-cost commercial production technique. Here, we report an unconventional method suitable for environmentally friendly and low-cost mass-production of ZIFs. In this method, taking the synthesis of ZIF-8 as an example, ZnO was used instead of Zn(NO3)2 in traditional solvent synthesis methods and CO2 was introduced to dissolve ZnO in aqueous solution of 2-methylimidazole (HMeim) and form water soluble salt ([ZnMeim]+[MeimCOO]-) at room temperature. Then, by removing CO2 through heating or vacuuming, Meim-ions are produced and instantaneously assemble with [ZnMeim]+s to generate ZIF-8 without any by-product. Due to the absence of strong acid anions (such as NO3- and Cl- et al.) in solution, the washing of filter cake required in the conventional approaches could be omitted and the filtrate containing only water and HMeim could be reused completely. This method is really green as no waste gas or liquid generates because CO2 and water could be recycled perfectly. It overcomes almost all bottlenecks occurred in commercial production of ZIF-8 when using traditional methods. A pilot plant was established for mass-production of ZIF-8 and hundreds kilograms of ZIF-8 was produced, which indicates that the new method is not only environmentally friendly but also low cost and commercial accessibility. It is expected that the new method would open an avenue for commercial applications of ZIFs.
Auδ--Ov-Ti3+: Active site of MOx-Au/TiO2 catalysts for the aerobic oxidation of 5-hydroxymethylfurfural
Weiyao Yang, Mengchen Fu, Chenyu Yang, Yiwen Zhang, Chun Shen
2023, 8(3): 785-797. doi: 10.1016/j.gee.2021.09.006
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Despite wide applications of noble metal-based catalysts in 5-hydroxymethylfurfural (HMF) oxidation, promoting the catalytic performance at low loading amounts still remains a significant challenge. Herein, a series of metal oxide modified MO-Au/TiO2 (M = Fe, Co, Ni) catalysts with low Au loading amount of 0.5 wt% were synthesized. Addition of transition metal oxides promotes electron transfer and generation of the Au-Ov-Ti3+ interface. A combination study reveals that the dual-active site (Au-Ov-Ti3+) governs the catalytic performance of the rate-determining step, namely hydroxyl group oxidation. Au site facilitates chemisorption and activation of O2 molecules. At the same time, Ov-Ti3+ site acts as the role of “killing two birds with one stone”: enhancing adsorption of both reactants, accelerating the activation and dissociation of H2O, and facilitating activation of the adsorbed O2. Besides, superoxide radicals instead of base is the active oxygen species during the rate-determining step. On this basis, a FDCA yield of 71.2% was achieved under base-free conditions, complying with the “green chemistry” principle. This work provides a new strategy for the transition metal oxides modification of Au-based catalysts, which would be constructive for the rational design of other heterogeneous catalysts.
MOF-derived Zn-Co-Ni sulfides with hollow nanosword arrays for high-efficiency overall water and urea electrolysis
Xiaoqiang Du, Yangyang Ding, Xiaoshuang Zhang
2023, 8(3): 798-811. doi: 10.1016/j.gee.2021.09.007
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Water electrolysis is a promising technology to produce hydrogen but it was severely restricted by the slow oxygen evolution reaction (OER). Herein, we firstly reported an advanced electrocatalyst of MOF-derived hollow Zn-Co-Ni sulfides (ZnS@Co9S8@Ni3S2-1/2, abbreviated as ZCNS-1/2) nanosword arrays (NSAs) with remarkable hydrogen evolution reaction (HER), OER and corresponding water electrolysis performance. To reach a current density of 10 mA cm-2, the cell voltage of assembled ZCNS-1/2//ZCNS-1/2 for urea electrolysis (1.314 V) is 208 mV lower than that for water electrolysis (1.522 V) and stably catalyzed for over 15 h, substantially outperforming the most reported water and urea electrolysis electrocatalysts. Density functional theory calculations and experimental result clearly reveal that the properties of large electrochemical active surface area (ECSA) caused by hollow NSAs and fast charge transfer resulted from the Co9S8@Ni3S2 heterostructure endow the ZCNS-1/2 electrode with an enhanced electrocatalytic performance.
A fast and in-depth self-reconstruction of anion ligands optimized CoFe-based pre-catalysts for water oxidation
Qiuyan Jin, Hao Cui, Chengxin Wang
2023, 8(3): 812-819. doi: 10.1016/j.gee.2021.10.002
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The design of efficient and robust non-precious metal electrocatalysts towards oxygen evolution reaction (OER) is of great value for developing green energy technologies. The in-situ formed high-valence (oxy)hydroxides species during the reconstruction process of pre-catalysts are recognized as the real contributing sites for OER. However, pre-catalysts generally undergo a slow and inadequate self-reconstruction. Herein, we reported a PO43- optimized CoFe-based OER catalysts with amorphous structure, which enables a fast and deep reconstruction during the OER process. The amorphous structure induced by ligands PO43- is prone to evolution and further form active species for OER. The electron interaction between metal sites can be modulated by electron-rich PO43-, which promotes generation of high active CoOOH. Simultaneously, the etching of PO43- from the pre-catalysts during the catalytic process is in favor of accelerating the self-reconstruction. As a result, as-prepared pre-catalyst can generate high active CoOOH at a low potential of 1.4 V and achieve an in-depth reconstructed nanosheet structure with abundant OER active sites. Our work provides a promising design of pre-catalysts for realizing efficient catalysis of water oxidation.
Accelerated prediction of Cu-based single-atom alloy catalysts for CO2 reduction by machine learning
Dashuai Wang, Runfeng Cao, Shaogang Hao, Chen Liang, Guangyong Chen, Pengfei Chen, Yang Li, Xiaolong Zou
2023, 8(3): 820-830. doi: 10.1016/j.gee.2021.10.003
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Various strategies, including controls of morphology, oxidation state, defect, and doping, have been developed to improve the performance of Cu-based catalysts for CO2 reduction reaction (CO2RR), generating a large amount of data. However, a unified understanding of underlying mechanism for further optimization is still lacking. In this work, combining first-principles calculations and machine learning (ML) techniques, we elucidate critical factors influencing the catalytic properties, taking Cu-based single atom alloys (SAAs) as examples. Our method relies on high-throughput calculations of 2669 CO adsorption configurations on 43 types of Cu-based SAAs with various surfaces. Extensive ML analyses reveal that low generalized coordination numbers and valence electron number are key features to determine catalytic performance. Applying our ML model with cross-group learning scheme, we demonstrate the model generalizes well between Cu-based SAAs with different alloying elements. Further, electronic structure calculations suggest surface negative center could enhance CO adsorption by back donating electrons to antibonding orbitals of CO. Finally, several SAAs, including PCu, AgCu, GaCu, ZnCu, SnCu, GeCu, InCu, and SiCu, are identified as promising CO2RR catalysts. Our work provides a paradigm for the rational design and fast screening of SAAs for various electrocatalytic reactions.
Oxygen vacancy defects engineering on Cu-doped Co3O4 for promoting effective COS hydrolysis
Guanyu Mu, Yan Zeng, Yong Zheng, Yanning Cao, Fujian Liu, Shijing Liang, Yingying Zhan, Lilong Jiang
2023, 8(3): 831-841. doi: 10.1016/j.gee.2021.11.001
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The activation of H2O is a key step of the COS hydrolysis, which may be tuned by oxygen vacancy defects in the catalysts. Herein, we have introduced Cu into Co3O4 to regulate the oxygen vacancy defect content of the catalysts. In situ DRIFTS and XPS spectra reveal that COS and H2O are adsorbed and activated by oxygen vacancy. The 10 at% Cu doped Co3O4 sample (10CuCo3O4) exhibits the optimal activity, 100% of COS conversion at 70 ℃. The improved oxygen vacancies of CuCo3O4 accelerate the activation of H2O to form active OH. COS binds with hydroxyl to form the intermediate HSCO2-, and then the activated -OH on the oxygen vacancy reacts with to form . Meanwhile, the catalyst exhibits high catalytic stability because copper species (Cu+/Cu2+) redox cycle mitigate the sulfation of Co3O4 (Co2+/Co3+). Our work offers a promising approach for the rational design of cobalt-related catalysts in the highly efficient hydrolysis COS process.
Synthesis of MgO-doped ordered mesoporous carbons by Mg2+-tannin coordination for efficient isomerization of glucose to fructose
Junyan Fu, Feng Shen, Xiaoning Liu, Xinhua Qi
2023, 8(3): 842-851. doi: 10.1016/j.gee.2021.11.010
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In-situ MgO-doped ordered mesoporous carbon (OMC@MgO) was fabricated by formaldehyde-free self-assembly method, in which biomass-derived tannin was used as carbon precursor replacing fossil-based phenolics, Mg2+ as both cross-linker and precursor of catalytic sites. Up to ∼20 wt% MgO could be doped in the carbon skeleton with good dispersion retaining well-ordered mesoporous structures, while more MgO content (35 wt%) led to the failing in the formation of ordered mesoporous structure. The OMC@MgO possessed a high specific surface area (298.8 m2 g-1), uniform pore size distribution (4.8 nm) and small crystallite size of MgO (1.73 nm) due to the confinement effect of ordered mesoporous structure. Using OMC@MgO as the heterogeneous catalyst, a maximum fructose yield of 32.4% with a selectivity up to 81.1% was achieved from glucose in water (90 ℃, 60 min), which is much higher than that obtained using the MgO doped active carbon via conventional post-impregnation method (26.5% yield with 58.3% selectivity). Higher reaction temperature (>90 ℃) resulted in decrease of selectivity due to the formation of humins. The designed OMC@MgO displayed tolerant to high initial glucose concentrations (10 wt%) and could remain good recyclability without significant loss of activity for three cycles.
Deep eutectic solvent-induced synthesis of Ni-Fe catalyst with excellent mass activity and stability for water oxidation
Ruichang Xue, Mengwei Guo, Zhuoming Wei, Qibo Zhang
2023, 8(3): 852-863. doi: 10.1016/j.gee.2021.11.006
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Ni-Fe bimetallic electrodes are currently recognized as a kind of benchmark transition metal-based oxygen evolution reaction (OER) electrocatalysts. Facile synthesis of Ni-Fe bimetallic electrode materials with excellent catalytic activity and satisfied stability by a simple and low-cost route is still a big challenge. Herein, well-defined Ni-Fe nanoparticles in-situ developed on a planar Fe substrate (Ni-Fe NPs/Fe) is fabricated via a facile one-step galvanic replacement reaction (GRR) carried out in an Ethaline-based deep eutectic solvent (DES). The prepared Ni-Fe NPs/Fe exhibits outstanding OER performance, which needs an overpotential of only 319 mV to drive a current density of 10 mA cm-2, with a small Tafel slope of 41.2 mV dec-1 in 1.0 mol L-1 KOH, high mass activity (up to 319.78 A g-1 at an overpotential of 300 mV) and robust durability for 200 h. Impressively, the Ni-Fe bimetallic oxygen-evolution electrode obtained from the Ethaline-based DES is catalytically more active and durable than that of its counterpart derived from the 4.2 mol L-1 NaCl aqueous solution. The reason for this is mainly related to the different morphology and surface state of the Ni-Fe catalysts obtained from these different solvent environments, particularly for the differences in phy-chemical properties, active species formed and deposition kinetics, offered by the Ethaline-based DES.
Heterostructuring noble-metal-free 1T' phase MoS2 with g-C3N4 hollow nanocages to improve the photocatalytic H2 evolution activity
Yanjun Xue, Yinghong Ji, Xinyu Wang, Huanli Wang, Xiaobo Chen, Xiaoli Zhang, Jian Tian
2023, 8(3): 864-873. doi: 10.1016/j.gee.2021.11.002
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In this work, we report the preparation of 1T'-MoS2/g-C3N4 nanocage (NC) heterostructure by loading 2D semi-metal noble-metal-free 1T'-MoS2 on the g-C3N4 nanocages (NCs). DFT calculation and experimental data have shown that the 1T'-MoS2/g-C3N4 NC heterostructure has a stronger light absorption capacity and larger specific surface area than pure g-C3N4 NCs and g-C3N4 nanosheets (NSs), and the presence of the co-catalysts 1T'-MoS2 can effectively inhibit the photoinduced carrier recombination. As a result, the 1T'-MoS2/g-C3N4 NC heterostructure with an optimum 1T'-MoS2 loading of 9 wt% displays a hydrogen evolution rate of 1949 μmol h-1 g-1, 162.4, 1.2, 1.5, 1.6 and 1.2 times than pure g-C3N4 NCs (12 μmol h-1 g-1), Pt/g-C3N4 NCs (1615 μmol h-1 g-1) and Pt/g-C3N4 nanosheets (NSs, 1297 μmol h-1 g-1), 1T'-MoS2/g-C3N4 nanosheets (1216 μmol h-1 g-1) and 2H-MoS2/g-C3N4 nanocages (1573 μmol h-1 g-1), respectively, and exhibits excellent cycle stability. Therefore, 1T'-MoS2/g-C3N4 NC heterostructure is a suitable photocatalyst for green H2 production.
Electrodeposited 3D hierarchical NiFe microflowers assembled from nanosheets robust for the selective electrooxidation of furfuryl alcohol
Biying Liu, Man Zhang, Yaoyu Liu, Yuchen Wang, Kai Yan
2023, 8(3): 874-882. doi: 10.1016/j.gee.2021.11.008
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A robust and green strategy for the selective upgrading of biomass-derived platform chemicals towards highly valuable products is important for the sustainable development. Herein, the efficient electrocatalytic oxidation of biomass-derived furfuryl alcohol (FFA) into furoic acid (FurAc) catalyzed by the electrodeposited non-precious NiFe microflowers was successfully reached under the low temperature and ambient pressure. The 3D hierarchical NiFe microflowers assembled from ultrathin nanosheets were controllably synthesized by the electrodeposition method and uniformly grown on carbon fiber paper (CFP). Electrochemical analysis confirmed that NiFe nanosheets more preferred in the selective oxidation of FFA (FFAOR) than oxygen evolution reaction (OER). The linear sweep voltammetry (LSV) in FFAOR displayed a clear decrease towards lower potential, resulting in 30 mV reduction of overpotential at 20 mA cm-2 compared with that of OER. The optimal catalyst Ni1Fe2 nanosheets exhibited the highest selectivity of FurAc (94.0%) and 81.4% conversion of FFA within 3 h. Besides, the influence of various reaction parameters on FFAOR was then explored in details. After that, the reaction pathway was investigated and rationally proposed. The outstanding performance for FFAOR can be ascribed to the unique structure of 3D flower-like NiFe nanosheets and oxygen vacancies, resulting in large exposure of active sites, faster electron transfer and enhanced adsorption of reactants. Our findings highlight a facile and convenient mean with a promising green future, which is promising for processing of various biomass-derived platform chemicals into value-added products.
CoSnO3/C nanocubes with oxygen vacancy as high-capacity cathode materials for rechargeable aluminum batteries
Shuainan Guo, Mingquan Liu, Haoyi Yang, Xin Feng, Ying Bai, Chuan Wu
2023, 8(3): 883-892. doi: 10.1016/j.gee.2021.11.009
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Rechargeable aluminum batteries (RABs) are attractive cadidates for next-generation energy storage and conversion, due to the low cost and high safety of Al resources, and high capacity of metal Al based on the three-electrons reaction mechanism. However, the development of RABs is greatly limited, because of the lack of advanced cathode materials, and their complicated and unclear reaction mechanisms. Exploring the novel nanostructured transition metal and carbon composites is an effective route for obtaining ideal cathode materials. In this work, we synthesize porous CoSnO3/C nanocubes with oxygen vacancies for utilizing as cathodes in RABs for the first time. The intrinsic structure stability of the mixed metal cations and carbon coating can improve the cycling performance of cathodes by regulating the internal strains of the electrodes during volume expansion. The nanocubes with porous structures contribute to fast mass transportation which improves the rate capability. In addition to this, abundant oxygen vacancies promote the adsorption affinity of cathodes, which improves storage capacity. As a result, the CoSnO3/C cathodes display an excellent reversible capacity of 292.1 mAh g-1 at 0.1 A g-1, a good rate performance with 109 mAh g-1 that is maintained even at 1 A g-1 and the provided stable cycling behavior for 500 cycles. Besides, a mechanism of intercalation of Al3+ within CoSnO3/C cathode is proposed for the electrochemical process. Overall, this work provides a step toward the development of advanced cathode materials for RABs by engineering novel nanostructured mixed transition-metal oxides with carbon composite and proposes novel insights into chemistry for RABs.
Imidazolium group prompted alkaline anion-exchange membrane with high performance for efficient electrochemical CO2 conversion
Min Wang, Qianqian Zou, Xueqi Dong, Nengneng Xu, Rong Shao, Jianfei Ding, Yidong Zhang, Jinli Qiao
2023, 8(3): 893-903. doi: 10.1016/j.gee.2021.12.003
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Development of high-performance hydroxide-conductive membranes is a focus research subject owing to promising applications in electrochemical reduction of CO2 (eCO2RR). However, few satisfactory membranes have been developed to maximize the performance of CO2 electrolyzers, despite its role as the core in regulating ion transport and preventing product crossover or fuel loss. Herein, we report the synthesis of alkaline anion-exchange membranes fabricated by poly (vinyl-alcohol) (PVA) and poly [(3-methyl-1-vinylimidazoliummethylsulfate)-co-(1-vinylpyrrolidone)] (PQ44) for use in CO2 electrolysis. Owing to the unique imidazolium ring structure coupled with a three-dimensional semi-interpenetrating porous internal architecture, the PVA/PQ44-OH- membranes provide a high hydroxide conductivity (21.47 mS cm-1), preferable mechanical property and thermal stability. In particular, the eCO2RR used PVA/PQ44-OH- as electrolyte membrane realized a charming Faradaic efficiency (88%) and partial current density (29 mA cm-2) at -0.96 VRHE and, delivered the excellent durability over 20 h electrolysis in 0.5 mol L-1 KHCO3 electrolyte. Notably, it can even enable an ultrahigh current density beyond 100 mA cm-2 at -1.11 VRHE when the electrolyte was KOH instead, and produced the FE of 85% at a low potential of -0.81 VRHE, superior to both commercial alkaline A201 and acidic Nafion117 membrane.
Plasma treated M1 MoVNbTeOx-CeO2 composite catalyst for improved performance of oxidative dehydrogenation of ethane
Shuairen Qian, Yuxin Chen, Binhang Yan, Yi Cheng
2023, 8(3): 904-914. doi: 10.1016/j.gee.2022.01.001
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High activity and productivity of MoVNbTeO catalyst are challenging tasks in oxidative dehydrogenation of ethane (ODHE) for industrial application. In this work, phase-pure M1 with 30 wt% CeO2 composite catalyst was treated by oxygen plasma to further enhance catalyst performance. The results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO2 capture active oxygen species in gas and transform V4+ to V5+ without damage to M1 structure. The space-time yield of ethylene of the plasma-treated catalyst was significantly increased, in which the catalyst shows an enhancement near ∼100% than that of phase-pure M1 at 400 ℃ for ODHE process. Plasma treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst materials. Energy conversion is achieved by using the catalyst as a medium.
Silk nanofibril as nanobinder for preparing COF nanosheet-based proton exchange membrane
Ping Li, Ningxin Zhang, Xuan Li, Shaokun Tang
2023, 8(3): 915-926. doi: 10.1016/j.gee.2022.05.008
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Abstract:
Two-dimensional covalent organic framework nanosheets (CONs) with ultrathin thickness and porous crystalline nature show substantial potential as novel membrane materials. However, bringing CONs materials into flexible membrane form is a monumental challenge due to the limitation of weak interactions among CONs. Herein, one-dimensional silk nanofibrils (SNFs) from silkworm cocoon are designed as the nanobinder to link sulfonated CON (SCON) into robust SCON-based membrane through vacuum-filtration method. Ultrathin and large lateral-sized SCONs are synthesized via bottom-up interface-confined synthesis approach. Benefiting from high length-diameter ratio of SNF and rich functional groups in both SNF and SCON, two-dimensional (2D) SCONs are effectively connected together by physical entanglement and strong H-bond interactions. The resultant SCON/SNF membrane displays dense structure, high mechanical integrity and good stability. Importantly, the rigid porous nanochannels of SCON, high-concentration -SO3H groups insides the pores and H-bonds at SCON-SNF interfaces impart SCON/SNF membrane high-rate proton transfer pathways. Consequently, a superior proton conductivity of 365 mS cm-1 is achieved at 80 ℃ and 100% RH by SCON/SNF membrane. This work offers a promising approach for connecting 2D CON materials into flexible membrane as high-performance solid electrolyte for hydrogen fuel cell and may be applied in membrane-related other fields.
Enhanced hydrodeoxygenation of lignin-derived anisole to arenes catalyzed by Mn-doped Cu/Al2O3
Xiaofei Wang, Shixiang Feng, Yue Wang, Yujun Zhao, Shouying Huang, Shengping Wang, Xinbin Ma
2023, 8(3): 927-937. doi: 10.1016/j.gee.2021.12.004
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Abstract:
Lignin is a renewable carbon resource to produce arenes due to its abundant aromatic structures. For the liquid-phase hydrodeoxygenation (HDO) based on metallic catalysts, the preservation of aromatic rings in lignin or its derivatives remains a challenge. Herein, we synthesized Mn-doped Cu/Al2O3 catalysts from layered double hydroxides (LDHs) for liquid-phase HDO of lignin-derived anisole. Mn doping significantly enhanced the selective deoxygenation of anisole to arenes and inhibited the saturated hydrogenation on Cu/Al2O3. With Mn doping increasing, the surface of Cu particles was modified with MnOx along with enhanced generation of oxygen vacancies (Ov). The evolution of active sites structure led to a controllable adsorption geometry of anisole, which was beneficial for increasing arenes selectivity. As a result, the arenes selectivity obtained on 4Cu/8Mn4AlOx was increased to be more than 6 folds of that value on 4Cu/4Al2O3 over the synergistic sites between metal Cu and Ov generated on MnOx.

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