Advanced Nanostructured Materials for Solar-Driven CO2 Photocatalytic Conversion: Progress, Mechanisms, and Future Perspectives

Abstract

Solar-driven photocatalytic carbon dioxide (CO2) conversion offers a sustainable pathway for mitigating anthropogenic CO2 emissions while simultaneously producing value-added fuels and chemicals using renewable solar energy. However, practical implementation remains constrained by the thermodynamic stability of CO2, inefficient visible-light utilization, rapid recombination of photogenerated charge carriers, sluggish interfacial reaction kinetics, and limited product selectivity. This review provides a comprehensive overview of recent progress in nanostructured photocatalysts for efficient solar-driven CO2 conversion, emphasizing material design, charge-transfer mechanisms, and structure–activity relationships. Fundamental aspects of CO2 adsorption, activation, thermodynamics, photogenerated charge separation, proton-coupled electron transfer, and reaction pathways toward carbon monoxide (CO), methane (CH4), methanol (CH3OH), and multi-carbon products are discussed. Particular attention is devoted to emerging photocatalytic platforms, including metal–organic frameworks, covalent organic frameworks, MXenes, graphitic carbon nitride, graphene-based materials, and carbon quantum dots. Recent synthetic and modification strategies involving dimensionality control, defect and surface engineering, heteroatom doping, cocatalyst incorporation, and interfacial coupling are critically examined. Advanced type-II, Z-scheme, S-scheme, and multicomponent heterojunctions are further highlighted for their ability to improve visible-light harvesting, preserve strong redox potentials, facilitate directional charge migration, and suppress electron–hole recombination. The mechanistic roles of active sites, surface vacancies, built-in electric fields, and reaction intermediates in governing catalytic activity and selectivity are also evaluated. Finally, persistent challenges associated with quantum efficiency, product selectivity, photocatalyst stability, mechanistic understanding, scalable synthesis, and practical reactor integration are outlined, together with future directions toward efficient, durable, selective, and commercially viable artificial photosynthetic systems for sustainable solar-fuel production.