Electron Transfer in Enzyme-Photo-Coupled Catalytic Systems: Mechanisms and Regulation Strategies

Enzyme-photo-coupled catalytic systems (EPCSs) integrate the light-harvesting capacity of photocatalytic modules with the selectivity of enzymatic modules to enable light-driven green synthesis, where electron transfer serves as the central bridge linking photon input to enzymatic turnover. This review focuses on electron transfer mechanisms and their regulatory strategies in photoenzymatic catalysis. In addition to natural photoenzymes, redox enzymes such as P450, laccase, and glucose oxidase are also applied in EPCSs, and the electron transfer pathways mainly include cofactor-dependent and cofactor-independent routes. Porous photocatalytic materials generate excited-state electrons under illumination, and this review describes three types of electron transfer in different electrode materials. In photoenzymatic catalysis, the directed transfer of photocatalytically generated electrons to enzymes proceeds via cofactor-mediated, direct-contact, and electron donor–acceptor (EDA) complex-type pathways, and their transfer mechanisms, distance dependence, and application scenarios are compared. Optimization strategies are reviewed from the perspectives of enzyme engineering, photocatalytic material engineering, and interface engineering. Finally, future directions, such as AI-driven photoenzyme design and artificial electron chain construction, are proposed. This work provides a theoretical framework for a deeper understanding of electron transfer behavior in photoenzymatic catalysis and for the design of highly efficient hybrid catalytic systems.