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 −0.1 V (vs. RHE). The ECO₂RR system established by CuInSe₂ and PV₃Mo₉ achieved the widest CO/H₂ range (1.0–5.1), with a maximum j_CO of −29.3 mA·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.