Activating SnO x -coated Cu 2 O photocathodes for efficient photoelectrochemical CO 2 reduction and unassisted tandem device integration

The Cu 2 O photocathode, with uniformly distributed SnO x nanoparticles, enabled efficient CO 2 to formate conversion. When integrated with semitransparent BiVO 4 photoanode, the tandem device achieved concurrent formate production at both electrodes.