Solar‐Driven In Situ Hydrogen Peroxide Production Over Metal‐Free Carbon Nitrides for Environmental Remediation

Photocatalytic hydrogen peroxide (H 2 O 2 ) generation using H 2 O and O 2 , when coupled with simultaneous environmental remediation, offers an attractive strategy to enhance solar‐to‐chemical conversion efficiency by improving charge‐carrier utilization and minimizing energy losses. Among the various photocatalysts (PCs) explored, graphitic carbon nitrides (g‐C 3 N 4 ) have garnered significant attention owing to their metal‐free composition, chemical stability, and environmental compatibility. However, their practical performance remains constrained by intrinsic limitations, such as rapid electron–hole recombination, sluggish surface reaction kinetics, and low selectivity toward the oxygen reduction reaction. Addressing these challenges requires a detailed understanding of the underlying reaction mechanisms and the structure–activity relationships governing the photocatalytic behavior. This minireview provides a concise overview of the fundamental pathways involved in photocatalytic H 2 O 2 production and highlights recent advancements in metal‐free modification strategies for g‐C 3 N 4 . Particular emphasis is placed on how these modifications impact key photocatalytic properties, such as light absorption, charge separation and transport, and surface reactivity. Importantly, the review discusses the emerging integration of in situ H 2 O 2 generation with environmental remediation processes, including pollutant degradation, biomass oxidation, and microbial disinfection. By linking catalyst design principles with practical remediation outcomes, this work aims to offer guidance for the rational development of efficient carbon nitride–based PCs for sustainable, decentralized environmental applications.