Selective CO2 Reduction to Formate on a Zn-Based Electrocatalyst Promoted by Tellurium

摘要

Zn-based materials represent a class of low-cost,promising electrocatalysts for CO2 reduction but the tuning of catalytic activity and selectivity by varying composition and nanostructure is a challenge.Herein,a ZnTe/ZnO heterostruc-tured material supported on N-doped carbon nanosheets(ZnTe/ZnO(S)C)is prepared with a novel ZnTe metal-organic framework(MOF).The hybrid material exhibits greatly enhanced perform-ances for CO2 reduction to formate with a sustained current density of 16 mA cm~(-2)and a selectivity of 86 at-1.1 V vs reversible hydrogen electrode(RHE)in bicarbonate solutions.The observation of Te-promoted CO2 reduction to formate,with high activity and selectivity,is notable in contrast to other Zn-based electrocatalysts.Density functional theory(DFT)analysis implies that selective formate formation is promoted by the stabilization of the key HCOO* intermediate on ZnTe.Additionally,ZnTe/ZnO@C is also an excellent catalyst for oxygen evolution owing to its high electrical conductivity and the high degree of covalency in ZnTe.The bifunctionality of ZnTe/ZnO@C toward both reactions is demonstrated by assembling a two-electrode electrochemical cell for CO2/H2O splitting and a fascinating rechargeable Zn-CO2 battery.The latter,when constructed with ZnTe/ZnO@C as the cathode and Zn foil as the anode,yields a Zn-CO2 battery fully based on Zn-based materials.