Co doped MoS2 as cocatalyst considerably improved photocatalytic hydrogen evolution of g-C3N4 in an alkalescent environment

Abstract The Gibbs free energy of MoS2 for H+ absorption is near-zero, which is considered to be a promising cocatalyst for H2 production. Nevertheless, the activity of MoS2 for HER is greatly limited by the acidic environment. Herein, we study that Co-doped MoS2 (Co-MoS2) nanosheets can realize an extremely efficient photocatalytic H2 production of g-C3N4 nanosheet (NSs) in alkalescent environment, such as triethanolamine (TEOA). The optimized Co-MoS2/g-C3N4 hybrids exhibits extremely boosted photocatalytic H2 evolution rate of 3193 μmol-1 h-1 g-1, approximately 2.4, 6.0 and 42.0 times as much as MoS2/g-C3N4 (1326 μmol-1 h-1 g-1), CoS2/g-C3N4 (530 μmol-1 h-1 g-1) and pure g-C3N4 (76 μmol-1 h-1 g-1), respectively. Besides, we calculated the apparent quantum efficiency (AQE) of all photocatalysts under the light at λ=370 nm, and the AQE of Co-MoS2/g-C3N4 hybrids reaches 16.62%. DFT calculation and experimental data reveal that the outstanding HER activity of Co-MoS2/g-C3N4 hybrids is ascribed to the Co doping inducing the distortion of MoS2 crystal, which effectively reduces the H binding free energy for HER. The project of Co-MoS2/g-C3N4 hybrids provides experience on the progress of low-cost and highly effective photocatalysts for photocatalytic H2 evolution.