Photoelectrocatalytic CO₂ Reduction Using g-C₃N₄ Hybrids: Review and Perspectives

Photoelectrocatalysis (PEC) stands at the forefront of sustainable technologies, offering promising solutions for environmental remediation and CO2 reduction. This review delves into the synergistic integration of graphitic carbon nitride (g-C3N4) and metal–organic frameworks (MOFs), two advanced materials with transformative potential in PEC systems. The discussion spans critical aspects of PEC, including mechanisms underlying PEC oxidation and CO2 reduction, alongside innovative strategies for enhancing charge separation, surface reactions, and catalytic efficiency. Particular attention is devoted to MOF/g-C3N4 composites, which exhibit exceptional properties and synergistic effects that elevate PEC performance. The review further evaluates these materials’ techno-economic feasibility, sustainability metrics, and commercialization readiness, providing a holistic view of their practical applicability. By synthesizing the latest advancements and identifying key research gaps, this work highlights the transformative role of g-C3N4 and MOFs in shaping the future of sustainable PEC systems. Offering actionable insights into design innovations and process optimization, this review paves the way for scalable, cost-benign solutions to pressing global challenges.