Advances in the photocatalytic reduction functions of graphitic carbon nitride-based photocatalysts in environmental applications: A review

Sustainable green energy development and environmental pollution abatement are two major challenges for global development. In this context, photocatalytic reduction technology has broad application prospects in pollutant control and energy generation because of its excellent characteristics of solar light-driven reaction and lack of secondary pollution. Graphitic carbon nitride (g-C3N4) is a non-metallic semiconductor with high chemical stability, non-toxicity, and excellent photocatalytic performance. However, g-C3N4 still has several major limitations in terms of its practical applications, including poor photo-excited charge separation, narrow absorption of visible light, and a low specific surface area. Modified g-C3N4 composites, which play a critical role in photocatalytic reduction technology are also attracting increasing attention in the fields of energy and environment. To date, many modification strategies have been developed to achieve satisfactory photocatalytic performance. Herein, we present an overview of the photoreduction applications of g-C3N4-based photocatalysts (GBPs) for hydrogen production, detoxification, CO2 reduction, nitrogen fixation, and heavy metal reduction along with focus on the determination of the underlying mechanisms. Finally, the current challenges and research requirements of GBPs are proposed.