Photocatalytic and photothermal catalytic CO2 reduction with H2O from regulatory mechanism to catalyst structure design: a review

Photocatalytic and photothermal catalytic CO₂ reduction using H₂O as the hydrogen source presents a promising approach to simultaneously address environmental sustainability and renewable energy production. While substantial progress has been made in this field, existing reviews have predominantly focused on systems employing exogenous H₂ rather than the more environmentally benign H₂O-based reduction. The current photosynthetic efficiency remains constrained by fundamental challenges including limited spectral utilization, inefficient photothermal conversion, suboptimal carrier mobility and insufficient active site accessibility. A deeper understanding of the reaction fundamentals and a critical examination of recent advancements in catalyst design strategies can help overcome these issues. This review begins by introducing the fundamentals of photocatalytic and photothermal CO₂ reduction with H₂O. It then systematically analyzes several key performance-enhancement regulatory mechanisms: (i) hierarchical structure engineering for enhanced light absorption, (ii) functional nanostructure design for improved charge carrier dynamics, (iii) surface active site optimization for enhanced CO₂/H₂O adsorption or regulated the binding strength of reaction intermediates, (iv) synergistic photothermal-photocatalytic system design utilizing photothermal effect or plasmonic effect. Furthermore, advantages and limitations of various photocatalytic and photothermal catalyst designs are analyzed. Finally, recommendations and future perspectives for the development of highly efficient bifunctional catalysts provide valuable insights into the advancement of photocatalytic and photothermal CO₂ reduction with H₂O as the hydrogen source.