Synergetic effect of defects rich MoS2 and Ti3C2 MXene as cocatalysts for enhanced photocatalytic H-2 production activity of TiO2

The biggest challenging issue in photocatalytic hydrogen production is to efficiently separate the photoinduced electron-hole pairs and requires the enrichment of photoinduced electrons on the surface of photocatalysts. Herein, TiO2 nanosheets (NSs) are in situ grown on highly conductive Ti3C2 MXene and then MoS2 rich in molybdenum vacancies are uniformly distributed on TiO2@Ti3C2 composite through a two-step hydrothermal method. Thus, a unique structure of MoxS@TiO2@Ti3C2 composite with molybdenum vacancies and double co-catalysts (Ti3C2 and MoS2) is achieved. The photocatalytic H-2 production rate of MoxS@TiO2@Ti3C2 composite with an optimized hydrothermal treatment temperature (160 degrees C) is nearly 193 and 6 times higher than that of pure TiO2 NSs and MoS2@TiO2@Ti3C2 composites (160 degrees C). A large number of active sites with the enhanced specific activity for H-2 generation are induced by the introduction of molybdenum vacancies to MoS2 in MoxS@TiO2@Ti3C2 composites. The presence of molybdenum vacancies can suppress carrier recombination, which is beneficial to the reaction. Besides, the presences of Ti3C2 MXene and MoS2 are found to as double co-catalysts to enhance the electronic conductivity, resulting in an increase in efficiency for electron transfer.