Progress in the synthesis and applications of N-rich carbon nitride (C3N5)-based catalysts in environmental and energy catalysis

Photocatalytic processes have been at the forefront of environmental/energy catalysis due to its "green" property, which may play a crucial part in future carbon neutrality. N-rich polymer carbon nitride (C3N5) has emerged as a promising photocatalyst due to its efficient utilization of solar energy, and a wide variety of C3N5-based catalysts thus are developed for addressing the environmental pollution and energy crisis. However, current studies still need to be deepened, broadened, and updated. This review intends to comprehensively summarize the latest research progress of C3N5-based catalysts, especially focusing on their modulation strategies, environmental applications, and energy applications, which may offer some insights and references in developing better C3N5-based catalysts for environmental/energy catalysis. The main contents includes the modulation strategies (e.g., molecular structural control, heterojunction construction, elemental doping, and morphological control), environmental applications (e.g., air purification, and water treatment), energy applications (e.g., H2 evolution, H2O2 reduction, CO2 reduction, and ammonia synthesis), combined systems including the photocatalysis and other catalytic processes (e.g., electrocatalysis, piezocatalysis, and PMS AOPs) for energy/environmental applications, other non-photocatalytic applications (e.g., adsorption, electrocatalysis, and piezocatalysis), and the summary and possible directions.