Photocatalytic carbon dioxide to methane Energy Closed-Loop System: Carbon Neutrality Potential and Cutting-Edge Advances

The photocatalytic conversion of carbon dioxide to methane represents a promising strategy for achieving carbon neutrality by integrating renewable solar energy with chemical fuel production and utilization.This review systematically examines recent advances in catalyst design,reaction mechanisms,and system integration for constructing efficient carbon dioxide to methane energy closed-loop systems.Key breakthroughs include the development of high-performance catalysts such as single-atom Ru/Niobium pentoxide (96% methane selectivity) and interface-engineered heterostructures (93% selectivity), which address the kinetic challenges of the 8-electron reduction pathway through precise active site control and oxygen vacancy engineering. Mechanistic studies reveal the critical role of proton-coupled electron transfer (PCET) processes and intermediate stabilization in determining reaction selectivity. The integration of photocatalytic carbon dioxide reduction with methane combustion enables complete carbon cycling, where methane serves as both an energy carrier and a carbon vector, while combustion-derived heat can be recycled to enhance overall energy efficiency. However, challenges remain in scaling these technologies, including improving catalyst stability, optimizing system-level energy efficiency,and reducing gas separation costs. Future research should focus on developing robust hybrid photothermal-photocatalytic systems and integrating them with renewable energy infrastructure to realize practical deployment. This work provides a comprehensive framework for advancing carbon dioxide to methane conversion technologies and their role in sustainable energy systems.