S-scheme heterojunction of CoMoO4/PCN with lower overpotential for photocatalytic water oxidation

Photocatalytic water splitting is one of the effective ways to solve environmental problems and energy crisis. However, the sloughy kinetics of 4e - transfer in water oxidation reaction (WOR) severely limits the efficiency of overall water splitting. Herein, S-scheme heterojunction is constructed by decorating cobalt molybdate on polymeric carbon nitride (CoMoO 4 /PCN) to accelerate the carrier kinetics in WOR. The CoMoO 4 /PCN heterojunction is characterized by XRD, TEM, SEM, XPS and electrochemical tests. Experimental analysis and theoretical calculations reveal that S-scheme heterojunction increases the charge transfer kinetics and the photo-redox ability. Moreover, the decreased Gibbs free energies of intermediate species scale down the overpotential of WOR. Therefore, 2 wt% CoMoO 4 /PCN exhibits outstanding O 2 evolution rate of 34.6 (λ > 300 nm) and 6.2 μmol h −1 (λ > 420 nm), which are 10.8 and 3.6 times than PCN, respectively. This study reveals the key characteristics of PCN by using charge conducting materials to regulate carrier dynamics, which will lay a foundation for the development of photocatalytic O 2 reaction.