Flower-like MoS(2) on graphitic carbon nitride for enhanced photocatalytic and electrochemical hydrogen evolutions

Design of highly efficient catalysts has already been a challenge in the exploration of renewable energies based on nanotechnologies. Herein, a feasible strategy of three-dimensional (3D)/two-dimensional (2D) nanojunctions was employed to achieve a prominently enhanced activity in both solar hydrogen evolution and electrochemical hydrogen generation from water splitting. Flower-like MoS₂ nanoparticles with thin-layers were fabricated using a one-pot hydrothermal process and were further attached to g-C₃N₄ nanosheets via their (002) crystal planes to form an intimate face-to-face contact. The hybrid catalysts exhibited a red-shift to the visible light region with an enhanced absorption capacity. At the optimal loading of 0.5 wt% MoS₂, MoS₂/g-C₃N₄ exhibited the highest photocatalytic H₂ evolution rate of 867.6 μmol h⁻¹ g⁻¹ under simulated sunlight irradiations, which is 2.8 times as high as that of pure g-C₃N₄. Furthermore, the average photocatalytic H₂ evolution rate was elevated to ca. 5 times as high as that of pure g-C₃N₄ under visible light irradiations. The synergistic effect responsible for the enhanced HER (hydrogen evolution reaction) performance might be originated from the intimate interface between the light-harvesting g-C₃N₄ and MoS₂ as the active sites with the decreased overpotential, lowered charge-transfer resistance and increased electrical conductivity, leading to a more efficient charge separation and a higher reductive potential. In addition, the lower overpotential and smaller Tafel slope on 0.5 wt% MoS₂/g-C₃N₄ lead to the enhancement of electrochemical HER performance compared to pure g-C₃N₄. This work provides a feasible protocol for rational design of highly efficient HER electrocatalysts and photocatalysts towards future energy innovation.Yazi Liu, Xinyuan Xu, Jinqiang Zhang, Huayang Zhang, Wenjie Tian, Xiaojie Li, Moses O. Tade, Hongqi Sun, Shaobin Wan