A new, efficient and durable MoO2/Mo2C-C cocatalyst with the optimized composition and electronic structure via in-situ carburization for photocatalytic H2 evolution

Cocatalyst assisted photocatalytic H2 generation from water under mild conditions can meet the increasing demand for clean and sustainable energy, but efficient and super-stable photocatalyst has rarely been achieved by modulating the composition and structure of cocatalyst. Herein, a fantastic cocatalyst, MoO2/Mo2C nano-particles strongly anchored in conductive carbon matrix (MoO2/Mo2C-C), was accurately synthesized by in-situ carbonizing strategy and adopted as an efficient and robust cocatalyst for CdS photocatalytic H2 evolution. To our delight, the obtained MoO2/Mo2C-C cocatalyst is extremely stable, retaining the original activity even after two years storage in atmospheric conditions. The optimized MoO2/Mo2C-C-CdS-0.3 (MMCC-0.3) photocatalyst, coupling 30 wt% MoO2/Mo2C-C with CdS, delivers a substantial H2 evolution rate of 18.43 mmol h-1 g-1 and super stability of successive 90 h testing (conducted in 15-day) without a secondary sacrificial agent supplement, as well as a high apparent quantum efficiency of 14.13 %. Both experimental results and DFT calculations reveal that the unique MoO2/Mo2C-C cocatalyst not only merited with optimal hydrogen binding energy (Delta G*) and downshifted d-band center to lower the kinetic barrier of hydrogen evolution reaction, but also promise conductive carbon bridge, high quality interface, and exposed abundant active sites for CdS, which synergisti-cally work with enhanced visible light absorption and promoted charge separation to promise the outstanding activity and stability of MoO2/Mo2C-C-CdS photocatalyst. This work not only provides an efficient and low cost cocatalyst for practical application, but also offers valuable insights into the design of robust cocatalyst for photocatalyst and beyond.