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

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 heterostructured material supported on N-doped carbon nanosheets (ZnTe/ZnO@C) is prepared with a novel ZnTe metal–organic framework (MOF). The hybrid material exhibits greatly enhanced performances 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.