2021 Vol. 6, No. 1

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Editorial
Celebrating the 5th year of Green Energy & Environment (GEE)
Suojiang Zhang
2021, 6(1): 1-2. doi: 10.1016/j.gee.2021.02.007
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Research highlight
Unsupervised machine learning accelerates solid electrolyte discovery
Xu Zhang, Bin Tang, Zhen Zhou
2021, 6(1): 3-4. doi: 10.1016/j.gee.2019.12.003
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Viewpoint
Lithium slurry flow cell, a promising device for the future energy storage
Lan Zhang, Xiangkun Wu, Weiwei Qian, Haitao Zhang, Suojiang Zhang
2021, 6(1): 5-8. doi: 10.1016/j.gee.2020.09.012
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Lithium slurry flow cell (LSFC) is a novel energy storage device that combines the concept of both lithium ion batteries (LIBs) and flow batteries (FBs). Although it is hoped to inherit the advantages of both LIBs and FBs, such as high energy density, ease of fabrication, environmental friendly, independent energy and power density, to name but a few. While unfortunately, it still has many challenges to overcome before it becoming the future star in energy storage area. Here in this paper, we briefly recall its history and try to illustrate the main issues that hindering its research as well as application. As a typical interdisciplinary product, LSFC is definitely a promising candidate for large scale energy storage application, while obviously it still has a long way to go.
Short communication
Stabilizing supported gold catalysts in acetylene hydrochlorination by constructing an acetylene–deficient reaction phase
Bolin Wang, Yuxue Yue, Saisai Wang, Shujuan Shao, Zhi Chen, Xianhua Fang, Xiangxue Pang, Zhiyan Pan, Jia Zhao, Xiaonian Li
2021, 6(1): 9-14. doi: 10.1016/j.gee.2020.06.012
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In the process of acetylene hydrochlorination, the rapid deactivation of supported gold (Au) catalysts by acetylene is still a huge challenge. Here, we provide an innovative strategy for constructing an acetylene–deficient reaction phase on the active site by coating an ionic liquid film on the Au(H2O)/C surface. The reactant ratio of C2H2 to HCl in this acetylene–deficient reaction phase is 1:132, in contrast to the 1:1 M ratio in the gas phase, thus boosting the catalytic stability of Au(H2O)/C catalysts. The kinetic and theoretical analysis showed that the reduction of cationic gold by C2H2 and the generation of carbon deposition can be inhibited in this constructed reaction phase during reaction. The current work not only broadens the scope of supported Au catalysts in acetylene hydrochlorination, but also verifies the perspective of the tunability of stoichiometric balance, which can be used in other catalytic applications.
A novel hybrid digestion-gasification process integrated with membranes for efficient conversion of biomass to bio-alcohols
Xuezhong He
2021, 6(1): 15-21. doi: 10.1016/j.gee.2020.04.003
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There is an urgent need to develop technologies which enable the conversion of biomass into liquid biofuels to fill the gap between limited fossil fuel supplies and increasing worldwide demand. In order to achieve the EU 2030 vision of at least 15% of the fuels used in the road transportation sector will be biofuels derived from non-food biomass feedstocks, the R&D of clean, inexpensive, highly end-user compatible biofuels from a virtually inexhaustible source of biomass should be pursued to make breakthroughs in cost-effective biomass to liquid biofuels (BTL) technologies. Thus, an innovative, consolidated, and sustainable technology using a hybrid digestion-gasification process integrated with membranes to produce next generation bio-alcohols from different biomass feedstocks was designed. The proposed concept was theoretically estimated to achieve an overall BTL efficiency of 44% and a cost reduction for bioalcohol production of 18.6%. Moreover, this technology can potentially achieve an overall CO2 emission reduction of > 75% for road transport based on the preliminary analysis.
Short review
Synthesis of 2,5-diformylfuran from renewable carbohydrates and its applications: A review
Jinhang Dai
2021, 6(1): 22-32. doi: 10.1016/j.gee.2020.06.013
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The synthesis of fine chemicals and fuel candidates from renewable biomass-based feedstocks has attracted much attention due to declining fossil resource. Many value-added furan derivatives, such as 5-hydroxymethylfurfural (HMF), 2,5-diformyfuran (DFF) and 2,5-furandicarboxylic acid, have been successfully produced from carbohydrates. Among these, DFF, the aerobic oxidation product of HMF, is a key chemical and can be used in organic synthesis and functional polymer manufacture. In this review, different catalytic systems for the synthesis of DFF from monosaccharide, disaccharide and polysaccharide were summarized, while reaction pathways and catalyst stability were also commented. Besides, the applications of DFF were introduced in brief. Then, prospects of more effective methods to DFF production and application were discussed.
Review article
Recent advancements in metal–organic frameworks for green applications
Chongxiong Duan, Yi Yu, Jing Xiao, Yuanyuan Li, Pengfei Yang, Fei Hu, Hongxia Xi
2021, 6(1): 33-49. doi: 10.1016/j.gee.2020.04.006
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A series of environmental and energy issues, such as global warming, water pollution, acid rain, and energy shortage, have to be settled urgently. Metal–organic frameworks (MOFs) are compounds consisting of metal ions or clusters coordinated to organic ligands, which show great promise for alleviating or mitigating these challenges owing to their outstanding physical and chemical properties. In this review, we summarize the recent advances of MOFs in the fields of green applications, including carbon capture, harmful gas removal, sewage treatment, and green energy storage. In addition, the challenges and prospects of the large-scale commercialized use of MOFs in handling environmental issues are also discussed.
The application and progress of bioelectrochemical systems (BESs) in soil remediation: A review
Tian Li, Ruixiang Li, Qixing Zhou
2021, 6(1): 50-65. doi: 10.1016/j.gee.2020.06.026
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Soil pollution endangers human health and ecological balance, which is why finding a highly efficient way to deal with pollutants is necessary. Biological method is an environmentally friendly treatment method. Bioelectrochemical systems (BESs), which combine electrochemistry with biological methods, have been widely used to remediate polluted environments, including wastewater, sludge, sediment, and soil. In BESs, redox reactions occur on electrodes with electroactive bacteria, which convert pollutants into low-polluting or nonpolluting substances. With BESs being a promising technology in the remediation field, the decontamination mechanisms and applications in soil conducted by BESs have attracted much attention. Therefore, to better understand the research progress of BESs, this paper mainly summarizes the mechanism of different classified BESs. The applications of microbial fuel cells (MFCs) in four pollutants (petroleum, heavy metals, pesticides, antibiotics) and the possible applications of microbial electrolysis cells (MECs) in soil are discussed. The main problems in BESs and possible future development directions are also evaluated.
Research paper
Novel HBD-Containing Zn (dobdc) (datz) as efficiently heterogeneous catalyst for CO2 chemical conversion under mild conditions
Jianwen Lan, Ye Qu, Ping Xu, Jianmin Sun
2021, 6(1): 66-74. doi: 10.1016/j.gee.2019.12.005
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A novel Zn-based metal–organic framework Zn (dobdc) (datz) [Zn2(H2dobdc) (datz)2·1.5DMF] with plentiful hydrogen bond donors (HBD) groups was facilely synthesized from mixed ligands. The dual activation of metal Zn sites and HBD groups for epoxides by forming Zn–O adduct and hydrogen bonds facilitated the ring-opening of epoxide substrate, which is critical for the subsequent CO2 fixation. Also, the existence of micropores and N-rich units in Zn (dobdc) (datz) afforded affinity towards CO2, which is beneficial to further improvement on catalytic CO2 conversion performance. Satisfactorily, Zn (dobdc) (datz)/Bu4NBr system was proved efficient heterogeneous catalyst for the CO2 cycloaddition with epoxides, and 98% propylene carbonate yield was obtained under mild conditions (80 °C, 1.5 MPa and solvent-free). In addition, Zn (dobdc) (datz)/Bu4NBr exhibited remarkable versatility to different epoxides and could be completely recycled over six runs with high catalytic activity. The highly stable, easily recycle and solvent-free Zn-based MOF reported here displays eco-friendly and efficient performance to CO2 conversion.
Confining MoS2 nanocrystals in MOF-derived carbon for high performance lithium and potassium storage
Chen Hu, Kun Ma, Yanjie Hu, Aiping Chen, Petr Saha, Hao Jiang, Chunzhong Li
2021, 6(1): 75-82. doi: 10.1016/j.gee.2020.02.001
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Developing an efficient synthesis protocol to simultaneously control 2D nanomaterials’ size and dispersion is the pivot to optimize their electrochemical performance. Herein, we report the synthesis of uniform MoS2 nanocrystals well-anchored into the void space of porous carbon (donated as MoS2⊂C hybrids) by a simple confined reaction in metal–organic framework (MOF) during carbonization process. The strong confinement effect refrain MoS2 growth and aggregation, generating abundant active centers and edges, which contribute fast lithium/potassium reaction kinetics. In addition to the hybridization with the derived carbon, the MoS2⊂C hybrids exhibit rapid Li+ transfer rate (∼10−9 cm2 s−1) and greatly improved electronic conductivity. Consequently, the MoS2⊂C hybrids show ultrafast rate performances and satisfactory cycling stabilities as anode materials for both lithium and potassium ion batteries. This work demonstrates a universal tactic to achieve high dispersive 2D nanomaterials with tailorable particle size.
Kinetics study of CO2 absorption in potassium carbonate solution promoted by diethylenetriamine
Rouzbeh Ramezani, Renzo Di Felice
2021, 6(1): 83-90. doi: 10.1016/j.gee.2019.11.004
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In this work, characterization and kinetics of CO2 absorption in potassium carbonate (K2CO3) solution promoted by diethylenetriamine (DETA) were investigated. Kinetics measurements were performed using a stirred cell reactor in the temperature range of 303.15–323.15 K and total concentration up to 2.5 kmol m−3. The density, viscosity, physical solubility, CO2 diffusivity and absorption rate of CO2 in the solution were determined. The reaction kinetics between CO2 and K2CO3 + DETA solution were examined. Pseudo-first order kinetic constants were also predicted by zwitterion mechanism. It was revealed that the addition of small amounts of DETA to K2CO3 results in a significant enhancement in CO2 absorption rate. The reaction order and activation energy were found to be 1.6 and 35.6 kJ mol−1, respectively. In terms of reaction rate constant, DETA showed a better performance compared to the other promoters such as MEA, EAE, proline, arginine, taurine, histidine and alanine.
Metallurgical pyrolysis toward Co@Nitrogen-doped carbon composite for lithium storage
Yanyan Liu, Kang Sun, Jianchun Jiang, Wenshu Zhou, Yuan Shang, Chenxia Du, Baojun Li
2021, 6(1): 91-101. doi: 10.1016/j.gee.2020.03.003
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Elemental state matter-heteroatom-doped carbon composites are of great importance for the development of anode in lithium ion batteries (LIBs). In this article, metal–organic frameworks (MOFs) are adopted as precursor to prepare Co composites via metallurgical pyrolysis under controllable conditions. The obtained nitrogen-doped porous carbon-Co nanocomposite possesses core–shell structure (Co@C–N). Co@C–N exhibits the best Li storage performances as anode active matter. After the 200th cycles at current density of 0.2 A g−1, a reversible capacity of 870 mAh g−1 is retained. A reversible capacity of 275 mAh g−1 still maintains with 5 A g−1. Co@C–N presents a high reversible capacity with excellent cycle stability. Considering the corresponding experimental and theoretical results, the Co0-based N-doped porous carbon composite is proposed to work as LIBs anode matter. These results provide a new design idea for electrode matters of metallic ion battery, and demonstrate that MOFs pyrolysis is an effective method for the construction of elemental state anode materials.
The adsorption properties of NaY zeolite for separation of ethylene glycol and 1,2-butanediol: Experiment and molecular modelling
Pei Xiong, Peng He, Yixin Qu, Liguo Wang, Yan Cao, Shuang Xu, Jiaqiang Chen, Muhammad Ammar, Huiquan Li
2021, 6(1): 102-113. doi: 10.1016/j.gee.2019.12.006
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The separation of ethylene glycol (EG) and 1,2-butanediol (1,2-BDO) azeotrope in the synthesis process of EG via coal and biomass is becoming of increasing commercial and environmental importance. Selective adsorption is deemed as the most promising methods because of energy saving and environment favorable. In this paper, NaY zeolite was used to separate 1,2-BDO from EG, and its adsorption properties was then investigated. The isotherms of EG and 1,2-BDO in vapor and liquid phases from 298 to 328 K indicated that they fitted Langmuir model quite well, and the NaY zeolite absorbent favored EG more than 1,2-BDO. The Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation techniques were conducted to investigate the competition adsorption and diffusion characteristics in different adsorption regions. It was observed that EG and 1,2-BDO molecules all have the most probable locations of the center of the 12-membered ring near the Na cations. The diffusivities of EG are lower than those of 1,2-BDO at the same adsorption concentration. At last, the breakthrough curves of the binary mixture regressed from the empirical Dose–Response model in fixed-bed column showed that the adsorption selectivity of EG could reach to as high as 2.43, verified that the NaY zeolite could effectively separate EG from 1,2-BDO. This work is also helpful for further separation of other dihydric alcohol mixtures from coal and biomass fermentation.
Investigation the improvement of high voltage spinel LiNi0.5Mn1.5O4 cathode material by anneal process for lithium ion batteries
Chao Gao, Haiping Liu, Sifu Bi, Huilin Li, Chengshuai Ma
2021, 6(1): 114-123. doi: 10.1016/j.gee.2020.03.001
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The spinel LiNi0.5Mn1.5O4 (LNMO) has been attracted great attention as lithium ion cathode material due to its high voltage and large energy density. However, the practical application of LNMO is still limited by poor cycling stability. Herein, to improve the cycling stability of spinel LNMO, it was treated with anneal process at 900 °C for 2 h after prepared by traditional solid-state method (LNMO-A). LNMO-A sample presented better electrochemical property especially under high rate, with capacity of 91.2 mAh g−1 after 1000 cycles under 10 C. Its superior electrochemical property was ascribed to the anneal process, resulting a stable crystal structure, indicated by XRD and Raman results of electrodes after 1000 cycles under 10 C and the longer solid-solution reaction, revealed by in-situ XRD. In addition, the optimized particle size, micro morphology and the larger BET area surface induced by the recrystallization in anneal process also contributes to its superior electrochemical property. What's more, the thin layer, which interacted LNMO-A particles with each other, induced by particles remelting in anneal process is also beneficial for its excellent electrochemical property. This study not only improved the electrochemical properties by anneal process, but also revealed the origins and mechanisms for its improvement.
Hydrolysis hydrogen production mechanism of Mg10Ni10Ce alloy surface modified by SnO2 nanotubes in different aqueous systems
Xiaojiang Hou, Lu Yang, Kaiming Hou, Hongchang Shi, Lei Feng, Guoquan Suo, Xiaohui Ye, Li Zhang, Yanling Yang
2021, 6(1): 124-137. doi: 10.1016/j.gee.2020.05.003
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(Mg-10wt%Ni)-10wt%Ce (Mg10Ni10Ce) was ball-milled with SnO2 nanotubes and Mg10Ni10Ce-xSnO2 (x = 0, 5, 10 and 15 wt%) composites have been prepared. The phase compositions, microstructures, morphologies and hydrolysis H2 generation performance in different aqueous systems (distilled water, tap water and simulated seawater) have been investigated and the corresponding hydrolysis mechanism of Mg10Ni10Ce and Mg10Ni10CeSnO2 has been proposed. Adding a small amount of SnO2 nanotubes can significantly enhance the hydrolysis reaction of Mg10Ni10Ce, especially the initial hydrolysis kinetics and the final H2 generation yield. Unfortunately, the Mg10Ni10Ce-xSnO2 hardly reacts with distilled water at room temperature. The hydrolysis reaction rate of Mg10Ni10Ce5SnO2 composite in tap water is still very slow with only 17.3% generation yield after 1 h at 303 K. Fortunately, in simulated seawater (3.5 wt% NaCl solution), the hydrolytic H2 generation behavior of the Mg10Ni10Ce5SnO2 composite has been greatly improved, which can release as high as 468.6 mL g−1 H2 with about 60.9% generation yield within 30 s at 303 K. The Cl− destroys the passivation layer on MgNiCe alloy surface and the added SnO2 nanotubes accelerate the hydrolysis reaction rate and enhance the H2 generation yield. The Mg10Ni10Ce5SnO2 composite can rapidly generate a large amount of H2 in simulated seawater in a short time, which is expected to be applied on portable H2 generators in the future.
Cross-polymerization between the model furans and phenolics in bio-oil with acid or alkaline catalysts
Qing Xu, Xun Hu, Lijun Zhang, Kai Sun, Yuewen Shao, Zhiran Gao, Qing Liu, Chun-Zhu Li
2021, 6(1): 138-149. doi: 10.1016/j.gee.2020.03.009
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Polymerization is a major challenge for the upgrading of bio-oil to biofuels, but is preferable for the production of carbon material from bio-oil. Understanding the mechanism for polymerization is of importance for tailoring property of carbon material. This study investigated the characteristics for the polymerisation of furfural, vanillin, their cross-polymerization and the impacts of catalysts on their polymerization. The results indicated that the organic acids like acetic acid and formic acid could catalyze the polymerisation of furfural, while H2SO4 or NaOH as catalyst could drastically enhance the degree of polymerization of furfural. Vanillin showed a higher tendency towards polymerization than furfural and H2SO4 or NaOH significantly facilitated the polymerization of vanillin via shifting the pasty product to solid polymer. The cross-polymerization between furfural and vanillin occurred even in the absence of catalyst, while the presence of H2SO4 or NaOH catalyst resulted in the formation of more solid polymer via cross-polymerization. The polymerisation reactions were accompanied with the consumption of –C=O via aldol addition/condensation reactions. In addition, the morphology and thermal stability of the polymers formed were affected by both the type of the catalysts employed, which can in turn enhance the cross-polymerization between furfural and vanillin.
Understanding the molecular structure of HSW coal at atomic level: A comprehensive characterization from combined experimental and computational study
Wei Feng, Zhuangmei Li, Hongfeng Gao, Qiang Wang, Hongcun Bai, Ping Li
2021, 6(1): 150-159. doi: 10.1016/j.gee.2020.03.013
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In this work, the coal samples from Hongshiwan (HSW) mining area, Ningxia, northwest of China, are characterized by using several modern materials characterization techniques, such as proximate and ultimate analyses, solid state 13C nuclear magnetic resonance (13C NMR), X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy (FT-IR). Then the key information about elements, valence, and chemical bonding for coal molecular structural construction is obtained. The results reveal that the main structure of HSW coal has 75.96% aromatic skeleton in mass. The ratio of aromatic bridge carbon to aromatic peripheral carbon of HSW coal is 0.315, indicating more naphthalene than benzene and anthracene in coal structures. Oxygen predominantly presents in the forms of ether (C–O), carbonyl (CO) and carboxyl (–COO). Nitrogen presents in the forms of both pyridine and pyrrole. Methyl (–CH3) group is predominant in cyclic and aliphatic hydrocarbons. Based on obtained structural information and the approaches of average molecular structure, the single molecular formula of HSW coal is defined as C221H148O28N2, with a molecular weight of 3142.32. Also, the 2D and 3D molecular model of HSW coal are built with computer-aided modeling. The model is optimized and further verified by FT-IR and 13C NMR spectra simulation with quantum chemical calculations. Besides, a more complicated structure of complex model for HSW coal containing 10 single-molecules is also obtained. Therefore, molecular structure of HSW coal has been comprehensively depicted and understood at atomic level from both experimental and quantum chemical approaches in the current work.

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