Rational Design Of Electrocatalysts And Regulating The Products Distribution Of Electrocatalytic CO₂ Reduction

Since the industrial revolution,due to the over-exploitation of fossil energy,the concentration of carbon dioxide in the atmosphere has risen sharply,causing many problems such as global warming and ocean acidification.Directly using electricity to drive electrochemical reduction of carbon dioxide to obtain high-value chemicals is a promising route,which could effectively store intermittent electric energy generated by solar and wind energy as well.However,due to the thermodynamic and kinetic stability of carbon dioxide,the activation of carbon dioxide requires a high energy barrier.Moreover,the hydrogen evolution reactions with faster kinetic process seriously affects the activity and selectivity of electrocatalytic reduction of carbon dioxide.Therefore,it is critical to develop highly efficient and stable electrocatalysts.In this article,we use bimetallic catalysts and supported catalysts as the research objects to discuss how the synergy between the two different components in the catalysts enhance the performance of electrocatalytic CO2 reduction.And we also provide strategies to develop the highefficiency catalysts.This article is mainly summarized as follows::1)We used ternary metal sulfides with different metal ratios as precursors to obtain bimetallic catalysts by in-situ pre-reduction,and discussed the performance of bimetallic catalysts in the electrochemical reduction of carbon dioxide.Among the catalysts,the AI5S8 derived from AgInsS8 showed a FEHCOOH of 91.7%,and JHCOOH reached-19.6 mA/cm2.The FEHCOOH of AIS2 derived from AgInS2 reached 82.6%,and the current density reached a high level of-29.9 mA/cm2.Experimental evidence shows that due to the introduction of silver,the catalyst forms a quasi-core-shell structure with a unique electronic structure during the in-situ pre-reduction process.By optimizing the adsorption energy barrier of the intermediates and accelerating the charge transfer rate,the performance for electrochemical CO2 reduction to the formic acid is improved.2)The electrochemical reduction of carbon dioxide to ethylene is one of the most promising strategies to reduce carbon dioxide emissions while producing high valueadded chemicals.We synthesized a g-C3N4 supported Cu2O composite material.The FEC2H4 of the composite reached 32.2%,and the partial current density of ethylene reached-4.3 mA/cm2.We found that g-C3N4 has intrinsic activity of electrocatalytic CO2 reduction to CO.The g-C3N4 support not only enhance the dispersion of Cu2O particles,but also enrich CO around Cu2O,thus improve the activity of the composite for CO2RR to ethylene.Our findings highlight the importance of the g-C3N4 support,a unique two-dimensional material,including not only the strong CO2 adsorption and activation capacity but also its synergistic effect with the cuprous oxide in CO2RR selectivity.