Understanding the unique Ohmic-junction for enhancing the photocatalytic activity of CoS2/MgIn2S4 towards hydrogen production

Abstract

MgIn2S4 is a photocatalyst with a suitable band gap for renewable energy production, but its effectiveness is hindered by pronounced photocorrosion, insufficient surface active sites and rapid charge recombination. Herein, we report the synthesis of CoS2/MgIn2S4 Ohmic junction with a robust internal electric field. The optimized CoS2/MgIn2S4 photocatalyst with a CoS2 loading of 20.5 wt%, depicts a maximum H2 evolution rate of 290 μmol g−1 h−1, which is 3.1 times higher than the value of MgIn2S4. The improved photocatalytic activity of CoS2/MgIn2S4 can be attributed to the intimate Ohmic junction at the CoS2/MgIn2S4 interface, which promotes effective photoelectron transfer from MgIn2S4 to CoS2. Simultaneously, CoS2 can act as an efficient surface cocatalyst, with an optimal hydrogen-adsorption Gibbs free energy, enabling highly efficient proton reduction at the catalyst/H2O interface. The present work introduces a novel approach to modulate interfaces, creating transition metal sulfide cocatalysts for photocatalysts, resulting in high photocatalytic performance.