Gallium modulated tin oxide for continuous production of formic acid via durable acidic CO electroreduction.

CO reduction catalyst corrosion and H evolution remain challenging under the strongly acidic electrolyte. Here, Ga-modulated SnO was investigated to achieve a good Sn oxidation state stability for durable (> 4000 hours) acidic CO reduction to HCOOH. Under pH 1.7, catalysts achieved a partial current density of 440 mA cm at -1.63 V and the highest single-pass conversion efficiency (SPCE) of 91.9%. In a 10 cm electrolyzer, a total current of ~986.3 milliampere is exhibited for more than 4000 hours with Faradaic efficiency of HCOOH (FE) higher than 82% and SPCE higher than 50%. Mechanism study indicates that lattice oxygen anchoring effect of Ga due to its strong oxygen affinity establishes a stable framework, reinforcing interface Sn─O bonds and protecting the Sn from the heavy self-reduction process. The robust structure of catalyst and modulated active Sn sites elevate the CO reduction activity. The durable and highly efficient catalytic system exhibits the potential for industrial applications of the Ga-modulated SnO.