Defects rich g-C3N4 with mesoporous structure for efficient photocatalytic H2 production under visible light irradiation

By Daming Ruan, Sooyeon Kim, M. Fujitsuka, T. Majima. Applied Catalysis B: Environmental, 2018

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Abstract Graphitic carbon nitride (g-C3N4) is a promising visible-light-driven photocatalyst for solar energy conversion by splitting water into H2. However, the photocatalytic performance of g-C3N4 is not sufficient because of low surface area and fast recombination of charge carriers. Here, g-C3N4 with nanosheet structure was prepared by using mixture of melamine (M) and urea (U) as the precursors for the photocatalytic H2 production from water. The use of U increased the surface area with mesoporous structure and defects of nitrogen vacancies acting as trap states in g-C3N4. The as-obtained g-C3N4-M1U2 (1 and 2 denote the weight ratios of M and U, respectively) exhibited the photocatalytic H2 production rate of 3.1 mmol g−1 h−1 under λ ≥ 400 nm light irradiation and apparent quantum efficiency (AQE) of 74% at λ = 400 nm. Single-particle photoluminescence (PL), originated from charge recombination of photogenerated charge carriers, showed longer lifetime of charge carriers in g-C3N4-M1U2 than that in g-C3N4-M. Femtosecond time-resolved diffuse reflectance measurement was performed to observe the photogenerated electrons trapping in g-C3N4-MxUy. The results show that the electron trapping by the defects as trap states occurs faster in g-C3N4-MxUy than in g-C3N4-M. It is suggested that the use of U increases the defects as electron trap states, leading efficient photocatalytic H2 production.

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

View Paper: https://www.semanticscholar.org/paper/99952328e5f144d04b01a84998f499c62e9a02ef