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CO2 electroreduction into liquid fuels is of broad interest and benefits reducing the energy crisis and environment burdens. CuS has been reported to be a desirable candidate for CO2 electroreduction into formate; however, its formate selectivity and stability are still far from the demands of practical application. Herein, we report CuS nanoparticles exhibiting good Faradaic efficiency of formate (about 98 %) in CO2 electroreduction and its deactivation mechanism during the reaction. The deactivation of CuS was found to be associated with the reconstruction and S loss of CuS, which deteriorates the Faradaic efficiency of formate. Combined with ionic and gas analyses, the S atom in CuS was lost in the form of H2S, SO2, and SO42−, followed by the reconstruction of CuS into copper oxides. Such a catalyst reconstruction facilitates electroreductions of CO2 and H2O, respectively, into CO and H2, etc., resulting in the degradation of catalytical performance of CO2 electroreduction into formate. This work reveals the important role of S loss and reconstruction of metal sulfide catalysts during the electroreduction reaction, which may benefit the further development of CuS‐based electro‐catalyst for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

The photocatalytic cycloaddition reaction between CO 2 and epoxide is one of the most promising green routes for CO 2 utilization, for which high performance photocatalysts are intensely desired. Herein, we have constructed an S-scheme heterojunction of MIL-125@ZIF-67 modified by amino groups, which achieves a cyclic carbonate yield of as high as 99 % without employing any co-catalyst, outperforming the previously reported photocatalysts. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and in-situ electron paramagnetic resonance (EPR) spectroscopy reveal the important role of photogenerated electron migration from Lewis acid (Co) sites to the O atom of epoxide in triggering its ring-opening (the rate-determining step of CO 2 cycloaddition reaction) under the assistance of photogenerated hole. Synergistically and concurrently, the Lewis base (amino groups) sites activate CO 2 to CO 2 *, facilitating the following CO 2 cycloaddition. Such a synergistic effect provides a most favorable approach to design efficient heterogeneous photocatalysts with dual/multiple-active sites for CO 2 cycloaddition reaction., (© 2024 Wiley-VCH GmbH.)

CO 2 electroreduction into liquid fuels is of broad interest and benefits reducing the energy crisis and environment burdens. CuS has been reported to be a desirable candidate for CO 2 electroreduction into formate; however, its formate selectivity and stability are still far from the demands of practical application. Herein, we report CuS nanoparticles exhibiting good Faradaic efficiency of formate (about 98 %) in CO 2 electroreduction and its deactivation mechanism during the reaction. The deactivation of CuS was found to be associated with the reconstruction and S loss of CuS, which deteriorates the Faradaic efficiency of formate. Combined with ionic and gas analyses, the S atom in CuS was lost in the form of H 2 S, SO 2 , and SO 4 2- , followed by the reconstruction of CuS into copper oxides. Such a catalyst reconstruction facilitates electroreductions of CO 2 and H 2 O, respectively, into CO and H 2 , etc., resulting in the degradation of catalytical performance of CO 2 electroreduction into formate. This work reveals the important role of S loss and reconstruction of metal sulfide catalysts during the electroreduction reaction, which may benefit the further development of CuS-based electro-catalyst for CO 2 electroreduction., (© 2023 Wiley-VCH GmbH.)