Photocatalytic H₂ Evolution on TiO₂ Assembled with Ti₃C₂ MXene and Metallic 1T-WS₂ as Co-catalysts

The biggest challenging issue in photocatalysis is efficient separation of the photoinduced carriers and the aggregation of photoexcited electrons on photocatalyst's surface. In this paper, we report that double metallic co-catalysts Ti₃C₂ MXene and metallic octahedral (1T) phase tungsten disulfide (WS₂) act pathways transferring photoexcited electrons in assisting the photocatalytic H₂ evolution. TiO₂ nanosheets were in situ grown on highly conductive Ti₃C₂ MXenes and 1T-WS₂ nanoparticles were then uniformly distributed on TiO₂@Ti₃C₂ composite. Thus, a distinctive 1T-WS₂@TiO₂@Ti₃C₂ composite with double metallic co-catalysts was achieved, and the content of 1T phase reaches 73%. The photocatalytic H₂ evolution performance of 1T-WS₂@TiO₂@Ti₃C₂ composite with an optimized 15 wt% WS₂ ratio is nearly 50 times higher than that of TiO₂ nanosheets because of conductive Ti₃C₂ MXene and 1T-WS₂ resulting in the increase of electron transfer efficiency. Besides, the 1T-WS₂ on the surface of TiO₂@Ti₃C₂ composite enhances the Brunauer-Emmett-Teller surface area and boosts the density of active site.