Phase and interlayer effect of transition metal dichalcogenide cocatalyst toward photocatalytic hydrogen evolution: The case of MoSe2.

Graphical abstract The interlayer-expanded 1 T-MoSe 2 cocatalyst modified 2D-C 3 N 4 exhibits an ultra-high hydrogen evolution rate of 1672.6 μmol g−1 h−1 with AQE of 5.2% at 420 nm. The giant improved HER performance can be ascribed to the enhanced charge separation efficiency and favorable hydrogen evolution capacity of cocatalyst. Highlights • The interlayer-expanded 1T-MoSe 2 is for the first time utilized as cocatalyst in photocatalytic hydrogen evolution. • The MoSe 2 cocatalyst can effectively boost the HER performance of 2D-C 3 N 4 with AQE = 5.2% at 420 nm. • The interlayer-expanded 1T-phase structure leads to favorable hydrogen evolution capacity of MoSe 2 benifiting for HER. Abstract Visible-light-driven photocatalytic hydrogen evolution reaction (HER) is of far-reaching significance to address the energy and environmental issues. Owing to the seriously limited charge separation and surface catalytic conversion efficiency, cocatalyts especially noble-metals (e.g. Pt) are fundamentally required for this reaction. Transitional metal dichalcogenides (TMDs) represent a type of promising nonprecious cocatalysts, but they still lack effective strategies to optimize the performance. In this work, we report a rational design of MoSe 2 to form interlayer-expanded 1T-phase structure, to maximize the cocatalytic activity for photocatalytic HER by optimizing the surface activation ability for reaction molecule at both edge and basal sites. In a practical photocatalytic reaction, when intergrated with a semiconductor (two-dimensional carbon nitride, 2D-C 3 N 4), the hybrid exhibits a satisfactory hydrogen evolution rate (1672.6 μmol g−1 h−1, with external quantum efficiency of 5.2% at 420 nm) that greatly higher than the normal spacing 2H-MoSe 2 (186.7 μmol g−1 h−1) and most noble-metals (e.g. Au, Ag, Pd). The giant improved HER performance strongly demonstrates the superiority of the presented phase and interlayer engineering strategy. The formation mechanism of the specialized structure and the key factor affecting the performance are also discussed. This work may provide new avenues for the design of TMDs-based catalysts toward HER application. [ABSTRACT FROM AUTHOR]