Selective CO2 to Proportionally Tunable Syngas at Lower Onset Potential Enabled by Bimetallic Chalcogenides in Polyoxometalate Medium

Highly active noble metals and developed modified electrocatalysts are limited in terms of economy and kinetics for the electrocatalytic CO2 reduction reaction (ECO2RR), respectively. Herein, different bimetallic chalcogenides (CuInSe2, CuInS2, AgInS2) were found to have the ability to prepare proportionally tunable syngas in PV3Mo9 medium at an ultra-low onset potential of -0.1V (vs. RHE). The ECO2RR system established by CuInSe2 and PV3Mo9 achieved the widest CO/H2 range (1.0–5.1), with a maximum jCO of -29.3mA·cm-2. The PV3Mo9 medium had a positive effect on reducing the onset potential and improving the reaction kinetics. Theoretical calculations illustrated that the high activity of CuInSe2 in PV3Mo9 medium depended on the metal-like characteristic generated by the interaction of bimetallic orbitals and the mild regulation of *CO adsorption energy. This work demonstrates the broad application prospects of bimetallic chalcogenides in POM media in terms of ECO2RR activity and economic benefits.