Efficient photocatalytic hydrogen production under visible-light irradiation with 2D Molybdenum nitride cocatalyst

Efficient visible-light-driven hydrogen production in the absence of noble metal is one of the major challenges for the application of photocatalytic water splitting. Herein, using cadmium sulfide (CdS) as a typical photocatalyst, we report on the synthesis of composite photocatalyst (CdS/MN) with CdS nanoparticles attached on two-dimensional (2D) layered molybdenum nitride (MN). The introduction of MN brings drastically enhanced photocatalytic activity of CdS by more than eight times, with an optimized hydrogen-production rate of ~58.4 mmol·h-1·g-1 and an apparent quantum yield of 62.5%. Characterization results indicate the charge transfer from CdS to MN for more efficient utilization of long-lived photogenerated electrons, with average lifetime of photogenerated charge carriers in CdS and CdS/MN estimated as 3.40 and 4.63 ns, respectively, and that MN could help to reduce the overpotential (280 mV) of hydrogen production reaction. Therefore, the excellent photocatalytic performance is attributed to the cocatalytic effect of 2D MN that helps to facilitate the charge separation and provides reactive sites for promoting hydrogen production reaction. This work provides an excellent example of efficient photocatalytic systems consisting of earth-abundant elements.