Boosting photocatalytic overall water splitting by Co doping into MnO nanoparticles as oxygen evolution cocatalysts.

The effect of cobalt doping into a manganese oxide (tetragonal spinel MnO) nanoparticle cocatalyst up to Co/(Co + Mn) = 0.4 (mol/mol) on the activity of photocatalytic water oxidation was studied. Monodisperse ∼10 nm CoMnO (0 ≤y≤ 0.4) nanoparticles were uniformly loaded onto photocatalysts and converted to CoMnO nanoparticles through calcination. 40 mol% cobalt-doped MnO nanoparticle-loaded Rh@CrO/SrTiO photocatalyst exhibited 1.8 times-higher overall water splitting activity than that with pure MnO nanoparticles. Investigation on the band structure and electrocatalytic water oxidation activity of CoMnO nanoparticles revealed that the Co doping mainly contributes to the improvement of water oxidation kinetics on the surface of the cocatalyst nanoparticles.