Search

Graphitic carbon nitride (g-C3N4), an excellent metal-free photocatalyst, is a promising candidate for overall water splitting under visible light illumination. However, some drawbacks of g-C3N4, such as poor separation and transfer efficiency of photogenerated charge carriers, restrain its photocatalytic applications. Efficient photocatalytic water splitting could be achieved by combining g-C3N4with well suited divergent semiconductors to form a type-II heterojunction system. Herein, we fabricate a highly efficient type-II heterojunction system based on exfoliated titanium hydride (TiH1.92) nanoparticles (NPs) and g-C3N4nanosheets for photocatalytic water splitting. Through TiN bonding at the interface between g-C3N4and TiH1.92NPs, g-C3N4nanosheets can be coupled with TiH1.92NPs. Owing to their specific type-II heterostructures, strong interfacial interaction and band alignment, an efficient photocatalytic hydrogen evolution rate of 75.55 μmol h−1is obtained, which is 4.29-fold higher than that of bare g-C3N4. The developed g-C3N4/TiH1.92type-II heterostructures exhibit a quantum efficiency of 6.78% at λ= 420 nm. In general, this study further provides a creative route to design and develop other novel type-II heterostructured photocatalysts for efficient H2evolution under visible light illumination.

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-C3N4nanohybrid photocatalyst constructed from plasmonic WN NPs and graphitic carbon nitride (g-C3N4) nanosheets, a novel WN/CN photocatalyst for efficient photocatalytic H2evolution by water splitting in the visible light and NIR light regions. Owing to the strong interfacial interaction and well-suited band alignment between g-C3N4and metal-like WN, the optimal WN/CN-1 sample (1 wt% WN) achieved an efficient photocatalytic hydrogen evolution rate of 72.17 μmol h−1with 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−1under NIR irradiation with an AQY of 0.46% at λ= 720 nm. In contrast, no hydrogen production is observed on bare g-C3N4under 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.

Photocatalytic water splitting is a promising approach to solar-to-fuel conversion. In recent years, graphitic carbon nitride (g-C3N4) has triggered worldwide interest due to its eco-friendliness, low cost, and visible-light activity as a semiconductor polymer photocatalyst. However, rapid recombination of photoinduced charge carriers and low efficiency are key issues hindering the practical application of g-C3N4in the efficient photocatalytic hydrogen (H2) production field. Herein, we fabricate a novel g-C3N4-based composite coupled with levorotatory-tryptophan (denoted as CN/l-trp) through π–π interactions and hydrogen bonds to improve the photocatalytic performance. The redox amino acid l-trp small biomolecules act as a hole relay and thus accelerate the transfer process of holes from g-C3N4to triethanolamine (TEOA), which leads to more electrons shuttled to a Pt cocatalyst, and finally boosts the visible-light photocatalytic H2evolution reaction (HER). When introducing 10 wt% l-trp, the photocatalytic H2production rate of g-C3N4/10 wt% l-trp (CN/10 wt% l-trp) loaded with 1.0 wt% Pt cocatalyst composite is prominently enhanced up to 1046.0 μmol h−1g−1, which is four times that of g-C3N4loaded with 1.0 wt% Pt cocatalyst (260.2 μmol h−1g−1). Our study provides a novel strategy to develop an efficient, green and stable g-C3N4-based hybrid photocatalyst for potential application in solar-to-hydrogen energy conversion.