Carbon-coated cubic-phase molybdenum carbide nanoparticle for enhanced photocatalytic H2-evolution performance of TiO2

Abstract

Conventional hexagonal dimolybdenum carbide (Mo 2 C) as a good cocatalyst has been widely applied for the enhanced photocatalytic hydrogen production of various photocatalysts. Compared with the hexagonal Mo 2 C, however, the investigation about cubic molybdenum carbide (MoC) is still very limited in photocatalytic field. In this study, carbon-coated cubic molybdenum carbide (MoC@C) nanoparticle was synthesized and used as an effective cocatalyst to improve the H 2 -evolution efficiency of TiO 2 . The cubic MoC@C can be obtained by adjusting the mass ratio of C 3 N 3 (NH 2 ) 3 to (NH 4 ) 6 Mo 7 O 24 (2:1) and controlling the calcination temperature to 800 °C. When the above cubic MoC@C nanoparticles were evenly loaded on the TiO 2 via a sonication-assisted deposition, a homogeneous composite of TiO 2 /MoC@C was formed due to the strong coupling interface between TiO 2 and cubic MoC nanoparticles. More importantly, the highest H 2 -production rate of TiO 2 /MoC@C reached 504 μmol h −1 g −1 (AQE=1.43%), which was 50 times as high as that of the pure TiO 2 . The enhanced performance of TiO 2 /MoC@C can be attributed to the synergistic effect of carbon layer as an electron mediator and the cubic MoC as interfacial H 2 -evolution active sites. This work provides a feasible guideline to develop high-efficiency Mo-based cocatalysts for potential applications in the H 2 -evolution field. The synergetic effect (carbon layer and cubic MoC) can promote the rapidly transmit of photogenerated electrons and the interfacial H 2 -evolution reaction, resulting in the promoted hydrogen-production rate of TiO 2 .