Metallic Vanadium Nitride as a Noble-Metal-Free Cocatalyst Efficiently Catalyzes Photocatalytic Hydrogen Production with CdS Nanoparticles under Visible Light Irradiation

Developing highly efficient H-2 production cocatalysts based on earth-abundant elements is of significant importance for large-scale conversion of solar light energy to clean H-2 energy via photocatalytic water splitting on semiconductor photocatalysts. Herein, we report that metallic vanadium nitride (VN) could serve as an efficient cocatalyst to greatly promote the photocatalytic H-2 production on the CdS photocatalyst under visible light irradiation (>= 420 nm). When CdS is combined with 15 wt % VN, the resulting CdS/VN photocatalyst (denoted as CN15) exhibits the highest photocatalytic H-2 production rate of 6.24 mmol h(-1) g(-1), which is 6.7 times higher than that of pristine CdS. The apparent quantum efficiency (AQE) of photocatalytic H-2 production over CN15 is determined to be 5.3% at 420 nm. In addition, the H-2 production activity of CN15 is stable after six cycles of continuous light irradiation of 30 h. Photoluminescence (PL) analyses and photoelectrochemical measurements show that the VN acting as a cocatalyst can not only promote the interfacial charge transfer from CdS to VN to enhance the photogenerated charge separation efficiency but also efficiently catalyze H-2 production with low overpotential, which may account for the enhanced photocatalytic activity. This work confirms that VN is an efficient noble-metal-free cocatalyst for solar photocatalytic H-2 production.