The integration of non-thermal plasma (NTP) with heterogeneous catalysis has emerged as a promising strategy for the efficient abatement of industrial volatile organic compounds (VOCs), overcoming key limitations of conventional thermal and standalone plasma technologies. This review provides a comprehensive overview of the synergistic mechanisms in NTP-catalytic systems, with particular emphasis on the bidirectional interactions between plasma and the catalyst. Specifically, plasma can activate catalysts through surface defect generation and improved metal dispersion, while catalysts, in turn, modulate plasma characteristics via localized electric field enhancement and electron energy redistribution. Furthermore, this synergy spans multiple spatiotemporal scales, linking ultrafast electron dynamics with macroscopic catalytic performance, and atomic-scale active sites with reactor-level behavior. Based on these mechanistic insights, rational catalyst design strategies are systematically discussed, including transition metal oxides, noble metals, perovskites, and metal–organic frameworks. Finally, key challenges related to catalyst deactivation, energy efficiency, and process scalability are highlighted. Future perspectives are proposed, focusing on advanced in situ diagnostics and AI-assisted material discovery to accelerate the practical implementation of NTP-catalytic technologies for sustainable VOC removal.

As a metal-free, visible-light-responsive two-dimensional (2D) layered semiconductor, graphitic carbon nitride (g-C₃N₄) has been extensively studied for photocatalytic water purification owing to its high chemical stability, facile synthesis, and low cost. However, single-phase g-C₃N₄ still suffers from bottlenecks including rapid photogenerated electron–hole pair recombination, low visible-light utilization efficiency, insufficient specific surface area, and a limited number of exposed surface active sites, which severely restrict its practical photocatalytic performance. Rational construction of heterojunctions with matched band alignment and intimate interfacial contact serves as an effective strategy to boost the photocatalytic activity of g-C₃N₄. This review introduces the structural characteristics and photocatalytic mechanisms of g-C₃N₄, summarizes the primary types of g-C₃N₄-based heterojunctions along with their charge transfer pathways, and highlights recent research progress in emerging contaminant degradation, pathogenic microbial disinfection, and reduction of high-valence and highly toxic heavy-metal ions for water decontamination. The review closes with critical perspectives on the rational design and practical engineering prospects of g-C₃N₄-based heterojunctions. By bridging heterojunction mechanisms with water-purification applications and engineering considerations, this review is expected to guide the rational design of high-performance g-C₃N₄-based heterojunctions and accelerate their translation toward practical water purification.