The photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu_(2)(OH)_(2)CO_(3)for stable photocatalytic CO_(2)reduction

Developing suitable photocatalysts and understanding their intrinsic catalytic mechanism remain key challenges in the pursuit of highly active,good selective,and long-term stable photocatalytic CO_(2)reduction(PCO_(2)R)systems.Herein,monoclinic Cu_(2)(OH)_(2)CO_(3)is firstly proven to be a new class of photocatalyst,which has excellent catalytic stability and selectivity for PCO_(2)R in the absence of any sacrificial agent and cocatalysts.Based on a Cu_(2)(OH)_(2)^(13)CO_(3)photocatalyst and 13CO_(2)two-sided^(13)C isotopic tracer strategy,and combined with in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)analysis and density functional theory(DFT)calculations,two main CO_(2)transformation routes,and the photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu_(2)(OH)_(2)CO_(3)are definitely revealed.The PCO_(2)R activity of Cu_(2)(OH)_(2)CO_(3)is comparable to some of state-of-the-art novel photocatalysts.Significantly,the PCO_(2)R properties can be further greatly enhanced by simply combining Cu_(2)(OH)_(2)CO_(3)with typical TiO_(2)to construct composites photocatalyst.The highest CO_(2)and CH_(4)production rates by 7.5 wt%Cu_(2)(OH)_(2)CO_(3)-TiO_(2)reach 16.4μmol g^(-1)h^(-1)and 116.0μmol g^(-1)h^(-1),respectively,which are even higher than that of some of PCO_(2)R systems containing sacrificial agents or precious metals modified photocatalysts.This work provides a better understanding for the PCO_(2)R mechanism at the atomic levels,and also indicates that basic carbonate photocatalysts have broad application potential in the future.

In-situ electrochemical interface of Cu@Ag/C towards the ethylene electrosynthesis with adequate ^(*)CO supply

The conversion of carbon dioxide to ethylene by electrochemical reduction (CO_(2)RR) provides a new strategy for achieving carbon dioxide conversion.However,copper-based catalysts have the disadvantages of unsatisfactory selectivity and low current density,which limit the potential CO_(2)RR industrial expansion.Researches have verified that the real reaction sites at the catalyst surface often undergo reconstruction during the reaction,therefore,understanding and utilizing this phenomenon is crucial for improving catalytic performance.In this work,we introduced additional Ag component into Cu@Ag/C tandem catalyst by in-situ electrochemical reconstruction of Cu_(2)CO_(3)(OH)_(2)/AgCl/C precursor.This electro-reduced catalyst exhibits a C_(2)H_(4)Faradaic efficiency of 50.41%in H-cell,and 58.03%in the flow cell,surpassing the counterparts of pure Cu and Ag,as well as the Cu-Ag homolog with separated interface.Moreover,it also provides a long-term stability of 21 h with the ethylene Faraday efficiency (FE) over 50%.The appropriate amount of Ag dopant into the Cu catalyst changes the electronic structure of Cu surface by the electron transfer from Cu to Ag,which distinctly enhances the binding energy of CO_(2) on the catalyst.Meanwhile,in-situ Raman results and theoretical calculation reveal that the introduction of silver increases the number of active sites and improves the coverage of*CO intermediate,thereby accelerating the kinetics of C–C coupling and reducing its energy barrier.The combination of cascade catalytic strategy and in-situ electroreduction interface provides potential applications for future artificial carbon balance.