Author: Maochang Liu (Xi'an Jiaotong University) - The potential of photocatalysis for producing renewable fuels is crucial for decarbonizing industries like chemical manufacturing and shipping. However, its efficiency and power output remain inadequate for industrial needs. While extensive research has focused on enhancing light absorption, carrier mobility, and catalytic activity, solar-to-chemical energy conversion efficiencies typically remain around or below 1%, despite advancements in material design. Using finite-time thermodynamics, we reassess light-driven conversion systems, including photocatalysis, natural photosynthesis, photovoltaics, and photothermal power. We argue that photocatalytic efficiency limitations are not just due to fast charge carrier lifetimes but are significantly impacted by molecular diffusion and transport at the energy output stage. To enhance practical applications, we propose exploring high-temperature gas-phase photocatalytic reactions, leveraging photothermal effects. Finite-time thermodynamics has traditionally been applied to analyze the efficiency and power of conventional energy systems. This work uniquely elucidates the time scales, efficiency, and power characteristics of various light-driven energy conversion systems, offering a theoretical framework and a roadmap for advancing the industrialization of photocatalysis.
