Latest ArticlesMetal-organic frameworks (MOFs) functionalized with open metal sites (OMSs) have received widespread attention in various applications due to their fascinating electronic properties and unique interactions with guest molecules. However, rational tailoring of the coordination environment of metal nodes during the synthesis of MOFs remains a great challenge due to their tendency of saturated coordination with linkers. Herein, we reported the construction of three new MOFs featuring unsaturated Cu(Ⅱ) sites, namely [Cu(HCOO)(pzta)]n (HL-1), {[Cu(PTA)0.5(pzta)(H2O)]·2H2O}n (HL-2) and [Cu(NA)0.5(pzta)]n (HL-3) (Hpzta = 3-pyrazinyl-1,2,4-triazole; PTA = terephthalic acid; NA = 1,4-naphthalene dicarboxylic acid), based on the mixed-linker strategy via specific selection of versatile Hpzta ligand and carboxylate ligands. Remarkably, the obtained MOFs exhibited excellent activity and good recyclability for the catalytic reduction of nitroaromatics under mild conditions (25 ℃ and 1 atm). In particular, the complete conversion of 4-nitrophenol (4-NP) took only 30 s on HL-2, reaching a record-high TOF value compared with previously reported metal catalysts. The combined experimental and theoretical studies on HL-2 revealed that the open Cu site with positive-charged nature could improve the adsorption and subsequent electron transport between the substrates, and was responsible for the outstanding performance. This work shined lights on the further enhancement of performance for MOFs through rational OMSs construction.
In the development of 3D conductive frameworks for lithium metal anode (LMA), two models have been proposed: top growth model and bottom-up growth model. However, Li tends to accumulate on the top of these 3D frameworks with homogenous lithiophilicity (top growth) and Li dendrite still forms. To address this issue, some researchers have focused on developing 3D frameworks with gradient lithiophilicity, which realized bottom-up growth of Li. Nevertheless, partial Li nucleation sites on the top of these frameworks were missed. Inspired by the two models talked above, this work firstly proposed a novel intermittent lithiophilic model for lithium deposition. To demonstrate the feasibility of this model, a bimetallic metal-organic frameworks derived ZnMn2O4-MnO nanoparticles were grown on carbon cloth for LMA. It can cycle stably under ultra-high current and areal capacity (10 mA/cm2, 10 mAh/cm2). The in-situ optical microscopy (OM) was conducted to observe the Li deposition behavior, no dendrite was found during 80 h in ester-based electrolyte while the pure Li only cycled for 2 h. What is more, it can also be well-coupled with LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode and solid-state electrolyte, which further prove the advantages of the intermittent model for the development of LMAs with high safety and high energy density.
Safety and energy density are significant for lithium-ion batteries (LIBs), and the flammable organic electrolyte is one of the most critical causes of the safety problem of LIBs. Although LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode with high capacity can improve the energy density, the interface stability between NCM811 cathode and electrolytes needs to be improved. Herein, we report a multifunctional additive, diethyl(2-(triethoxysilyl)ethyl)phosphonate (DETSP), which can suppress the flammability of the electrolyte and enhance the cycling stability of NCM811 cathode with a capacity retention of 89.9% after 400 cycles at 1 C, while that of the blank electrolyte is merely 61.3%. In addition, DETSP is compatible well with the graphite anode without impairing the electrochemical performances. Significantly, the performance and safety of NCM811/graphite full cells are also improved. Experimental and theoretical results demonstrate that DETSP can scavenge acidic byproducts and is beneficial to form a stable cathode-electrolyte interface (CEI). Accordingly, DETSP can potentially be an effective solution to ameliorating the safety of the commercial electrolyte and improving the stability of high-voltage cathodes.
Catalyst with high performance has drawn increasing attention recently due to its significant advantages in chemical reactions such as speeding up the reaction, lowering the reaction temperature or pressure, and proceeding without itself being consumed. Despite the superior catalytic performance of precious metal catalysts, transition metal oxides offer a promising route for substitution of precious metals in catalysis arising from their low cost, intrinsic activity and sufficient stability. Mullite-type oxide SmMn2O5 exhibits a unique crystal structure containing double crystalline fields, and nowadays is used widely as the catalyst in different chemical reactions, including the reactions of vehicle emissions reduction and oxygen evolution reaction, gas sensors, and metal-air batteries, promoting attention in catalytic performance enhancement. To our knowledge, there is no review article covering the comprehensive information of SmMn2O5 and its applications. Here we review the recent progress in understanding of the crystal structure of SmMn2O5 and its basic physical properties. We then summarize the catalytic sources of SmMn2O5 and reaction mechanisms, while the strategies to improve catalytic performance of SmMn2O5 are further presented. Finally, we provide a perspective on how to make further progress in catalytic applications.
Climate change is an important issue facing the world today and carbon reduction has become the focus of attention for all countries. Alternative bio-fuels are an important means to achieve carbon emission reduction. The production of jet fuel precursors from biomass by hydrothermal liquefaction (HTL) has received a lot of attention due to its mild conditions and environmental friendliness. Lignocellulosic biomass and algal biomass are considered as the second and the third generation biomasses as promising raw materials for alternative fuel preparation. Among them, lignocellulosic biomass has been extensively studied due to its wide range of sources and can be divided into one-step HTL and stepwise HTL according to the process method. Algal biomass has been extensively studied experimentally due to its short growth cycle and the fact that it can sequester large amounts of carbon without taking up arable land. In this paper, the feedstock composition of different biomasses is reviewed for the HTL of biomass. A detailed review of the process characteristics, reaction pathways and influencing factors for the HTL production of jet fuel precursors from lignocellulosic biomass and algal biomass is also presented. Theoretical references are provided for further process optimization and bio-crude quality upgrading.
With the low cost, excellent safety and high theoretical specific capacity, aqueous zinc-ion batteries (AZIBs) are considered as a potential rival for lithium-ion batteries to promote the sustainable development of large-scale energy storage technologies. However, the notorious Zn dendrites and low Coulombic efficiency (CE) limit further development of AZIBs, due to the unstable electrochemical deposition/stripping behavior of Zn anode in aqueous zinc ion electrolytes. In this review, critical issues and advances are summarized in electrolyte engineering strategies. These strategies are focused on active water molecules during electrochemical process, including high-concentration electrolytes, ionic liquids, gel-polymer electrolytes and functional additives. With suppressed active water molecules, the solvation and de-solvation behavior of Zn2+ can be regulated, thereby modulating the electrochemical performance of Zn anode. Finally, the inherent problems of these strategies are discussed, and some promising directions are provided on electrolytes engineering for high performance Zn anode in AZIBs.
Weakly-solvated electrolytes (WSEs) utilizing solvents with weak coordination ability offer advantages for low-potential graphite anode owing to their facile desolvation process and anions-derived inorganic-rich solid electrolyte interphase (SEI) film. However, these electrolytes face challenges in achieving a balance between the weak solvation affinity and high ionic conductivity, as well as between rigid inorganic-rich SEI and flexible SEI for long-term stability. Herein, we introduce 1,3-dioxolane (DOL) and lithium bis(trifluoromethanesulfonyl)-imide (LiTFSI) as functional additives into a WSE based on nonpolar cyclic ether (1,4-dioxane). The well-formulated WSE not only preserves the weakly solvated features and anion-dominated solvation sheath, but also utilizes DOL to contribute organic species for stabilizing the SEI layer. Benefitting from these merits, the optimized electrolyte enables graphite anode with excellent fast-charging performance (210 mAh/g at 5 C) and outstanding cycling stability (600 cycles with a capacity retention of 82.0% at room temperature and 400 cycles with a capacity retention of 80.4% at high temperature). Furthermore, the fabricated LiNi0.8Co0.1Mn0.1O2||graphite full cells demonstrate stable operation for 140 cycles with high capacity retention of 80.3%. This work highlights the potential of tailoring solvation sheath and interphase properties in WSEs for advanced electrolyte design in graphite-based lithium-ion batteries.
Urea is extensively used in agriculture and chemical industry, and it is produced on an industrial scale from CO2 and Haber–Bosch NH3 under relatively high temperature and high pressure conditions, which demands high energy input and generates masses of carbon footprint. The conversion of CO2 and N sources (such as NO2−, NO3−, and N2) through electrocatalytic reactions under ambient conditions is a promising alternative to realize efficient urea synthesis. Of note, the design of electrocatalyst is one of the key factors that can improve the efficiency and selectivity of C–N coupling reactions. Defect engineering is an intriguing strategy for regulating the electronic structure and charge density of electrocatalysts, which endows electrocatalysts with excellent physicochemical properties and optimized adsorption energy of the reaction intermediates to reduce the kinetic barriers. In this minireview, recent advances of defect engineered electrocatalysts in urea electrosynthesis from CO2 and various N reactants are firstly introduced. Mechanistic discussions of C–N coupling in these advances are presented, with the aim of directing future investigations on improving the urea yield. Finally, the prospects and challenges of defect engineered electrocatalysts for urea synthesis are discussed. This overview is expected to provide in-depth understanding of structure–reactivity relationship and shed light on future electrocatalytic C–N coupling reactions.
The widespread application of phenolic substances in the field of food, medicine and industry, is harmful to the environment and human health. Therefore, it is very important to develop a convenient and effective method to detect and degrade phenolic compounds. Herein, we report a new keggin-type polyoxometallate-based metal-organic complex self-assembled under solvothermal condition, {[Cu(dap)(3-PA)]4(SiW12O40)(H2O)2}·2H2O (1, dap = 1,2-diaminopropane, 3-HPA = 3-pyridineacrylic acid). 1 shows an interesting 1D ladder-like structure. As a bifunctional catalyst, 1 can be employed as a colorimetric sensor toward phenol with the relatively low detection limit (LOD) of 0.36 µmol/L (S/N = 3) in the wide range (0.001–0.1 mmol/L). The title colorimetric sensor is applied to determine phenol in various water environment with good recoveries ranging from 95%–105%. In addition, 1 also exhibits excellent photocatalytic degradation toward phenol under visible light with the highest removal efficiency at 96% for 100 min and wide pH universality. The selectivity, stability and reliability of the detection of 1 towards phenol, as well as the detection for 4-chlorophenol, o-cresol, 4-nitrophenol and phloroglucinol were studied. Furthermore, the photocatalytic reaction kinetics and the mechanisms of photodegradation of phenol were also investigated in detail.
For treatment of sulfion-containing wastewater, coupling the electrochemical sulfion oxidation reaction (SOR) with hydrogen evolution reaction (HER) can be an ideal way for sulfur and H2 resources recovery. Herein, we synthesize a metal-modified carbon nanotube arrays electrode (Co@NCNTs/CC) for SOR and HER. This electrode has excellent performance for SOR and HER attributed to the unique array structure. It can achieve 99.36 mA/cm2 at 0.6 V for SOR, and 10 mA/cm2 at 0.067 V for HER. Density functional theory calculations verify that metal modification is able to regulate the electronic structure of carbon nanotube, which is able to optimize the adsorption of intermediates. Employed Co@NCNTs/CC as bifunctional electrodes to establish a hybrid electrolytic cell can reduce about 67% of energy consumption compared with the traditional water splitting electrolytic cell. Finally, the hybrid electrolytic cell is used to treat actual sulfion-containing wastewater, achieving the sulfur yield of 30 mg h−1 cm−2 and the hydrogen production of 0.64 mL/min.
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