Photocatalytic Conversion of Biomass over Modified Graphitic Carbon Nitride Catalysts for Environmental Sustainability—A Review

Review Photocatalytic Conversion of Biomass over Modified Graphitic Carbon Nitride Catalysts for Environmental Sustainability—A Review Guangsheng Zhu 1, Yajie Shu 1,*, and Ming Zhou 2,* 1 National Local Joint Laboratory for Advanced Textile Processing and Clean Production, Wuhan Textile University, Wuhan 430200, China 2 School of Environment and Science, Gold Coast Campus, Griffith University, Gold Coast, QLD 4222, Australia * Correspondence: shuyj@[email protected] (Y.S.); [email protected] (M.Z.) Received: 18 November 2024; Revised: 29 January 2025; Accepted: 15 February 2025; Published: 20 February 2025 Abstract: Solar-driven photocatalytic transformations of biomass-derived organic wastes into high-value chemicals and fuels is a crucial and promising strategy for reducing pollution while simultaneously utilizing renewable sources and generating valuable products, contributing to a cleaner and more sustainable environment. However, its efficient conversion remains challenging due to its complex macromolecular structure and the demand for environmentally sustainable processing methods. Graphitic carbon nitride (g-C3N4) has emerged as a promising photocatalyst for biomass conversion owing to its unique electronic properties, intrinsic stability and structural tunability. This review comprehensively summarizes recent advancements in the modification of gC3N4-based photocatalysts for photocatalytic biomass conversion, focusing on strategies including elemental doping, defect engineering, and heterojunction construction. These modifications have enabled efficient conversion of various biomass feedstocks, from simple monosaccharides to complex cellulose structures, while facilitating simultaneous environmental pollution remediation. Furthermore, this review analyses the challenges in improving g-C3N4-based photocatalysts for biomass photo-reforming and improving the conversion of complex biomass substrates. Finally, by critically evaluating current strategies and highlighting future research directions, this review provides insights for designing advanced g-C3N4-based photocatalysts for biomass conversion and promotes environmental sustainability.