Electrothermal Water‐Gas Shift Reaction at Room Temperature with a Silicomolybdate‐Based Palladium Single‐Atom Catalyst

Abstract The water‐gas shift (WGS) reaction is often conducted at elevated temperature and requires energy‐intensive separation of hydrogen (H 2 ) from methane (CH 4 ), carbon dioxide (CO 2 ), and residual carbon monoxide (CO). Designing processes to decouple CO oxidation and H 2 production provides an alternative strategy to obtain high‐purity H 2 streams. We report an electrothermal WGS process combining thermal oxidation of CO on a silicomolybdic acid (SMA)‐supported Pd single‐atom catalyst (Pd 1 /CsSMA) and electrocatalytic H 2 evolution. The two half‐reactions are coupled through phosphomolybdic acid (PMA) as a redox mediator at a moderate anodic potential of 0.6 V (versus Ag/AgCl). Under optimized conditions, our catalyst exhibited a TOF of 1.2 s −1 with turnover numbers above 40 000 mol mol Pd −1 achieving stable H 2 production with a purity consistently exceeding 99.99 %.