Metallic WN plasmonic fabricated g-C3N4 significantly steered photocatalytic hydrogen evolution under visible and near-infrared light

Abstract

Semiconductor based photocatalysts are hardly employed to harvest broadband spectral light from the visible to near-infrared (NIR) light region due to bandgap limitations. Metallic and metal-like materials as photocatalysts are known to overcome this limitation through a plasmonic effect that can efficiently promote photocatalytic activity by converting the visible-NIR light photon energy into hot-electron energy. These energetic hot electrons undergo interband transition and transfer to adjacent semiconductors through an interfacial charge-transfer transition, thus inducing a photocatalytic reaction. Herein, we report a WN/g-C₃N₄ nanohybrid photocatalyst constructed from plasmonic WN NPs and graphitic carbon nitride (g-C₃N₄) nanosheets, a novel WN/CN photocatalyst for efficient photocatalytic H₂ evolution by water splitting in the visible light and NIR light regions. Owing to the strong interfacial interaction and well-suited band alignment between g-C₃N₄ and metal-like WN, the optimal WN/CN-1 sample (1 wt% WN) achieved an efficient photocatalytic hydrogen evolution rate of 72.17 μmol h⁻¹ with an apparent quantum yield of 6.23% at λ = 420 nm, which is about 4 times higher than that of bare g-C₃N₄ (17.17 μmol h⁻¹). Notably, the developed WN/CN-1 photocatalyst also exhibits a hydrogen evolution rate of 16.32 μmol h⁻¹ under NIR irradiation with an AQY of 0.46% at λ = 720 nm. In contrast, no hydrogen production is observed on bare g-C₃N₄ under NIR light photoirradiation (λ = 720 nm). The photocatalytic charge transfer transition mechanism of the plasmonic WN/CN nanocomposite is proposed, which is supported by density functional theory calculations. In general, this study provides a new creative approach to designing and developing other novel plasmonic antenna/reactor nanohybrids for plasmon-mediated chemical transformation by solar light.