Unveiling the origin of boosted photocatalytic hydrogen evolution in simultaneously (S, P, O)-Codoped and exfoliated ultrathin g-C3N4 nanosheets

By Qinqin Liu, Jiyou Shen, Xiaohui Yu, Xiaofei Yang, Wei Liu, Juan-Yu Yang, Hua Tang, Hui Xu, Huaming Li, Youyong Li and 1 more. Applied Catalysis B: Environmental, 2019

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Abstract Recently, metal-free graphitic carbon nitride (g-C3N4) has been recognized as a potential candidate for high-performance photocatalytic hydrogen production while challenges still remain due to poor electronic properties and limited surface active sites. We demonstrate that g-C3N4 can be simultaneously co-doped with S, P and O nonmetal-atoms and exfoliated into ultrathin 2D nanosheets with a thickness of ∼3 nm by a simple, sequential thermal synthesis. The multi-atoms doping and nanostructure modulation remarkably enhanced the photocatalytic hydrogen production under illumination, with the optimal H2 evolution rate reaching 2480 μmol g−1 h−1. First-principle calculations and experimental evidences suggest that, upon elemental doping within the g-C3N4 framework, S atoms occupied the interstitial sites and P and O atoms replaced the C and N atoms, respectively. Consequently, photo-induced charge transfer and separation significantly improved owing to the construction of a more favorable charge transfer pathway. Furthermore, introducing heteroatoms into the structure of g-C3N4 narrowed the bandgap and negatively shifted the conduction band edge, leading to extended visible-light absorption and stronger electron reducibility for subsequent H2 production. Importantly, the in-situ generated 2D g-C3N4 nanosheets exhibited more catalytic surface sites, which was highly beneficial to the photocatalytic water splitting.

Subfields: Electrical and Electronic Engineering, Materials Chemistry, Renewable Energy, Sustainability and the Environment

View Paper: https://www.semanticscholar.org/paper/23a22b2a3b3ed5432ea0d6c2beb361a224612d29