Bias-Free Solar-Driven Syngas Production: A Fe O Photoanode Featuring Single-Atom Cobalt Integrated with a Silver-Palladium Cathode.

Photoelectrochemical syngas production from aqueous CO is a promising technique for carbon capture and utilization. Herein, we demonstrate the efficient and tunable syngas production by integrating a single-atom cobalt-catalyst-decorated α-Fe O photoanode with a bimetallic Ag/Pd alloy cathode. A record syngas production activity of 81.9 μmol cm  h (CO/H ratio: ≈1 : 1) was achieved under artificial sunlight (AM 1.5 G) with an excellent durability. Systematic studies reveal that the Co single atoms effectively extract the holes from Fe O photoanodes and serve as active sites for promoting oxygen evolution. Simultaneously, the Pd and Ag atoms in bimetallic cathodes selectively adsorb CO and protons for facilitating CO production. Further incorporation with a photovoltaic, to allow solar light (>600 nm) to be utilized, yields a bias-free CO reduction device with solar-to-CO and solar-to-H conversion efficiencies up to 1.33 and 1.36 %, respectively.