Engineering product selectivity in photocatalytic CO2 reduction: fundamentals, mechanisms, and catalyst design

Abstract

The selective conversion of carbon dioxide (CO₂) into value-added products using solar energy represents a promising strategy for addressing climate change and advancing carbon-neutral energy systems. However, the inherent complexity of photocatalytic CO₂ reduction, involving multielectron and multiproton transfer steps with competing pathways, often leads to poor selectivity. This review provides a comprehensive overview of recent five-year advances and mechanistic insights into product selectivity in photocatalytic CO₂ reduction. The thermodynamic and kinetic fundamentals governing CO₂ activation were outlined, and the key intermediates and charge-carrier dynamics that dictate product distribution were then highlighted. Strategies for enhancing selectivity, including crystal facet engineering, cocatalyst integration, multi-active site design, and modulation of catalyst microenvironments, are subsequently discussed with representative examples. Advanced characterization techniques are examined for their role in elucidating structure–selectivity relationships. Finally, emerging trends are addressed, including artificial intelligence-driven catalyst discovery, tandem reactor systems, selective C₂₊ fuel production, and sustainable materials and device engineering. This review aims to provide design principles and forward-looking perspectives to guide the development of efficient, durable, and highly selective photocatalytic CO₂ conversion systems.