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 cadmium sulfide nanoparticles attached on 2D layered molybdenum nitride (MN). The introduction of molybdenum nitride brings drastically enhanced photocatalytic activity of cadmium sulfide by more than 8 times, with an optimized hydrogen-production rate of ~58.4 mmol h^-1 g^-1 and 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 molybdenum nitride 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 molybdenum nitride 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 system consisting of earth-abundant elements.