查看更多>>摘要：Photoactive two-dimensional covalent organic frameworks (2D-COFs) have recendy emerged as a promising platform for efficient solar to chemical energy conversion. The photosynthesis of a-trifluoromethylated ketones, which is an important access to various fluorine-containing compounds, is rarely reported in heterogeneous photocatalytic systems. Herein, we report two 2D-COFs constructed from the electron-deficient triazine and electron-rich benzotrithiophene units with imine and amide linkages for the photosynthesis of α-trifluoromethylated ketones. The novel triazine-based COFs showed good activity, broad substrate flexibility and recyclability under visible-light irradiation, which is much superior to the classical pyrene-based COFs. Density functional theory calculations revealed that the triazine-based COFs have intrinsically lower carrier recombination tendency and can produce more intermediates ·CF3, resulting in higher catalytic efficiency. This research will contribute to the rational design of photoactive COFs and facilitate the development of fluorine chemistry.
查看更多>>摘要：Using solar energy to obtain valuable fresh water through interface evaporation is a promising environmentally friendly technology. However, the organic pollutants in wastewater may cause potential water safety hazards. The removal of organic pollutants by H2O2 in-situ generated photocatalytically is an effective means to achieve water purification. In this work, a simple method is proposed for the controllable synthesis of C3N4/NiIn2S4 heterojunction, by which can be achieved both the efficient evaporation of the solar interface and the photo-catalytic production of H2O2. The evaporation rate and solar evaporation efficiency of C3N4/NiIn2S4 reach up to 3.25 kg·m~(-2)·h~(-1) and 215.06%, respectively, under the irradiation of one sun (1 kW·m~(-2)). Furthermore, C3N4/ NiIn2S4 heterojunction exhibits an excellent photocatalytic H2O2 production activity of 1080 μmol~(-1)·L~(-1)·h~(-1) . This study provides a facile and attractive strategy for the design of photothermal materials and photocatalysts with efficient interfacial evaporation and sewage purification, especially for complex sewage samples.
查看更多>>摘要：Element doping is an excellent strategy to promote charge separation and reaction kinetics of photocatalyst, which plays significant role in accelerating the sustainable energy development process. Herein, Ni, In co-doped ZnIn2S4 photocatalyst was prepared by a microwave-assisted solvothermal method. The rapid crystallization of ZnIn2S4 resulted in partial In atoms substituted Zn atom during the formation of [ZnS]4 layer. In doping in tetrahedral Zn sites increases the electron derealization around In sites, hence reduces the electronic potential wells along Z axis. Ni doping in tetrahedral Zn sites decreases the negative charge on the S sits, which balances the H adsorption/desorption, further boosting the photocatalytic activity. As a result, Ni, In co-doped ZnIn2S4 possess an optimal photocatalytic H2 evolution property of 21.94 μmol·h~(-1), which is nearly 1.8 and 6.1 times of In-ZnIn2S4 (11.78 μmol·h~(-1)) and ZnIn2S4 (3.6 μmol·h~(-1)).
查看更多>>摘要：Seawater splitting is considered as a promising way to replace water splitting for H2 production due to the enrichment of seawater resources. However, the development of this technology has been greatly hampered by the lack of efficient electrocatalysts and the detrimental effects of chlorine electrochemistry. Herein, we report a defect-rich low-crystalline Rh metallene (l-Rh metallene) with an amorphous/crystalline hetero-phase structure for seawater electrolysis, where chlorine generation is avoided by replacing the oxygen evolution reaction (OER) with the hydrazine oxidation reaction (HzOR). Benefiting from the large surface-to-volume ratio, abundant active sites and unique electronic structure, the l-Rh metallene exhibits out-standing catalytic activity for both hydrogen evolution reaction (HER, -38 mV at 10 mA cm~(-2)) and HzOR (-2 mV at 10 mA cm~(-2)). Notably, an ultra-low voltage of only 28 mV is required to achieve 10 mA cm~(-2) in two-electrode hydrazine-assisted seawater splitting system.
查看更多>>摘要：The transformation of y-valerolactone (GVL) into levulinic acid (LA) requires the use of bifunctional catalysts allowing the hydrogenation and lactonization steps to occur. The aim of this study is to clarify the role played by both redox (Ru) and acid (Nb) sites of the ruthenium-niobium-silicon mixed oxides catalysts, synthesized by sol-gel route, when this reaction is performed in mild conditions. The catalytic performances of the materials are related to an in-depth morphologic and structural characterization, demonstrating that the interaction between the two metals and their relative amount and dispersion are crucial in determining their activity. The results confirm the hydrogenation-dehydration consecutive reaction network and evidence the possibility to selectively produce either GVL or the intermediate γ-hydroxypentanoic acid by an accurate choice of the catalyst composition.
查看更多>>摘要：Defect type and interactions among active sites are critical in heterogeneous peroxymonosulfate (PMS) system. Herein, a continuous flow fixed bed PMS reactor with distilled spirits lees derived biochar (DSLBs)/quartz wool was designed to explore the synergistic roles of active sites. Satisfyingly, with high graphite N, C=O content and defect degree, DSLB-800 exhibited superior catalytic activity, durability and applicability for sulfamethoxazole (SMX) removal. The dominant contribution of ~1O2, and minor roles of SO4~(·-) and ·OH were confirmed. Single graphite N, C=O and C-O, combined interactions between graphite N and pyridine N, graphite N and pyrrole N, pyridine N and pyrrole N, C=O and O=C-O, O=C-O and C-O, as well as interactions among graphite N, pyridine N and pyrrole N contributed to ~1O2 generation. Notably, the double vacancy defect was also a preferential site for ~1O2 production. This study advances mechanistic understanding of collaborative contribution of active sites to PMS activation.
查看更多>>摘要：In this work, a highly efficient uranium extraction method from water by the piezo catalytic reduction-oxidation process is reported by utilizing a hollow cubic shaped Zn2SnO4/SnO2 as piezo catalyst. The electrons and holes in Zn2SnO4/SnO2 are separated efficiently under the irradiation of ultrasound. After that, some of the piezo electrons reduce the adsorbed U(VI) to UO2, the others react with soluble oxygen to form H2O2, and oxidize UO2 to generate (UO2)O2·2H2O, which could be efficiently separated from the solution. U(VI) piezo catalytic extraction rate could reach ~ 90% under the irradiation of ultrasonic waves (40 kHz, 120 W) within 5 h and only decreased by ~ 3% after four cycles. The present work advances piezo catalysis as a new route for uranium extraction from water, which may be applied in the extraction or removal of U(VI) in the U-containing wastewaters, providing new opportunities for resource-saving and environmental enhancement.
查看更多>>摘要：The low interfacial mass transfer efficiency between metal-organic framework (MOFs) and conductive substrates makes the development of MOFs-based photoelectrodes challenging. Herein, Ar-Fe2O3/Ti~(3+)-TiO2-NTs photo-electrodes are obtained through electrochemical reduction, pulsed deposition, MOFs self-assembly, and sculptural reduction processes. The target photoelectrodes achieve 100% degradation of tetracycline (TC) within 90 min, and the photo-electrocatalytic synergy factor is estimated to be 4.20. Ar-Fe2O3/Ti~(3+)-TiO2-NTs photoelectrodes also exhibit excellently in multiple antibiotics and real samples. The reduction self-doping of Ti~(3+) retains vertical orientation properties of nanotubes to provide a path for electronics, and heightens the light-harvesting capacity. The pulse deposition improves the dispersibility of Fe, which is beneficial to the self-assembly of MIL-100[Fe). After sculpture-reduction processes, Ar-Fe2O3 retains the porous structure of MIL-100(Fe), and the heterojunction formed with Ti~(3+)-TiO2-NTs can significantly enhance the interface charge transfer. This work enriches the electrochemical modification strategy of TiO2-NTs, and gives new insights into the development of MOFs-based photoelectrodes.
查看更多>>摘要：Nanocarbon-based advanced oxidation processes (AOPs) are widely used in wastewater purification. However, the properties of different carbon catalysts lead to differences in the organic degradation mechanism and toxicity of wastewater treatment. Herein, this study provides insight into the differences between the oxidation of sulfamethoxazole (SMX) by carbon nanotube (CNT)/peroxymonosulfate (PMS), nanodiamond (ND)/PMS and PMS-alone systems. The pseudo-first-order reaction constant of the reaction of the SO4~(·-)-dominated CNT/PMS system with SMX is 19-fold and 30-fold higher than those of the ~1O2-dominated ND/PMS system and PMS direct oxidation system at pH= 7, respectively. In addition, density functional theory (DFT) calculations and product analysis show that SO4~(·-) mainly attacks the aniline and sulfonyl groups, while oxidation of the aniline group is the dominant mode of PMS direct oxidation and ~1O2 reactivity. The formation of nitro and nitroso byproducts after SMX degradation determines the toxicity difference, and the CNT/PMS system is even more advantageous.
查看更多>>摘要：Electrocatalytic reduction of nitrate (NO3~-) to ammonia (NH3) in wastewater is a promising economic process for NH3 synthesis. This work designed and prepared Au1Cu (111) single-atom alloys with surface Cu vacancies (V_(Cu-) Au1Cu SAAs), which exhibited superior NH3 Faradaic efficiency (98.7%) with a production rate of 555 μg h~(-1) cm~(-2) at -0.2 V vs. RHE, while negligible activity decay was found after a durability test. Meanwhile, 97% of produced NH3 can be recovered by a simple membrane distillation. Characterizations evidence that electron migration from Cu to Au atoms creates electron-deficient Cu active sites in V_(Cu)-Au1Cu SAAs, which promote the generation of active hydrogen species (*H) that can readily hydrogenate NO3~-. Theoretical calculation reveals that the bi-functional Cu sites not only promote the activation of water to produce *H but also lower the energy barrier of *NH3 desorption from the catalyst surface.
NSTL