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

Abstract

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.

Recent Advances in Transition Metal Nitride‐Based Materials for Photocatalytic Applications

“…VN also shows considerable stability in photocatalytic reactions. [84] Qu et al demonstrated that the lattice matching and the heterojunctions formed between metallic NbN and CdS improved the photocatalytic activity (ten times higher than that of bulk CdS) (Figure 13c). Theoretical calculations revealed that NbN possesses strong adsorption for H 2 O on its surface.…”

“…For more TMNs used in photocatalysis, Tian et al reported that VN can be applied as a superior photocatalyst in water splitting. [84] In detail, VN-CdS photocatalyst can exhibit a high photocatalytic efficiency (6.24 mmol g -1 h -1 , 6.7 times higher than that of pristine CdS) (Figure 13a). This is because VN dramatically [83,175] Copyright 2017, Elsevier, Copyright 2019, American Chemical Society.…”

“…This is because VN dramatically [83,175] Copyright 2017, Elsevier, Copyright 2019, American Chemical Society. [84,179] Copyright 2019, American Chemical Society, Copyright 2018, Royal Society of Chemistry.…”

“…For example, Ta 3 N 5 , [71,72] InN, [73] and InGaN [74] have been used as potential semiconductor photocatalysts for water splitting due to their simple chemical composition, tunable narrow band gap, and stability. [41] In addition, some metallic nitrides such as TiN, [75] Fe x N, [76,77] Co x N, [78,79] Ni 3 N, [80,81] Mo x N, [82,83] VN, [84] and some relative ternary compounds are suitable as cocatalysts because they can act as active sites and promote the transportation of photoexcited electrons. Therefore, TMN is a type of material with a significant prospect for extensive applications in photocatalytic systems.…”

“…c) Photocatalytic H 2 production activities of different samples. Reproduced with permission [84,179]. Copyright 2019, American Chemical Society, Copyright 2018, Royal Society of Chemistry.…”