Graphitic Carbon Nitride Decorated with Nickel(II)-(3-Pyridyl) Benzimidazole Complexes and Pt Nanoparticles as a Cocatalyst for Photocatalytic Hydrogen Production from Water Splitting

• Published in: ACS applied nano materials Vol. 3; no. 11; pp. 10659 - 10667
• Main Authors: Kombo, Miza, Chong, Han-Bao, Ma, Liu-Bo, Sahar, Shafaq, Fang, Xiao-Xiang, Zhao, Tan, Ling, Cong, Lu, Xiao-Jie, Xu, An-Wu
• Format: Journal Article
• Language: English
• Published: American Chemical Society 25.11.2020
• Subjects: charge separation efficiency; hydrogen evolution; C3N4/NPBIm; recombination rate; type-II heterostructured photocatalyst
• ISSN: 2574-0970; 2574-0970
• DOI: 10.1021/acsanm.0c01872

Graphitic carbon nitride (g-C3N4) is regarded as a promising and suitable photocatalyst in the progress of hydrogen evolution from water splitting by employing visible-light irradiation. Nevertheless, the fast recombination rate of charge carriers of g-C3N4 results in a low H2 production rate. In this work, a high efficiency type-II heterostructured photocatalyst is constructed by decorating nickel­(II)-(3-pyridyl) benzimidazole (NPBIm) complexes and platinum as a cocatalyst of g-C3N4 nanosheets via the strategy of π–π interaction, and the interfacial charge transfer through g-C3N4/NPBIm interface is thus improved. The optimal sample with 6 wt % NPBIm loadings with visible-light irradiation (λ ≥ 420 nm) possesses a maximum H2 production rate of 46.97 μmol h–1, which is 3.5-fold higher than that of g-C3N4 alone (13.47 μmol h–1) with a quantum efficicency of 5.13% at 420 nm. Meanwhile, C3N4/6 wt % NPBIm hybrid nanocomposite exhibits good photocatalytic stability toward hydrogen production under visible-light irradiation, demonstrating that the type-II heterojunction photocatalyst has great potential in the practical applications. The separation and migration of photoinduced excitons are significantly enhanced between g-C3N4 and NPBIm nanosheets, as clearly revealed by photoluminescence (PL) spectra, time-resolved PL spectra, and photoelectrochemical results. Overall, this study could provide opportunity to design and develop other highly efficient type-II heterostructured photocatalyst for the enhancement of H2 evolution from H2O splitting under visible-light irradiation.