Electrode Architectures in Biophotoelectrochemical Systems for Sustainable Energy and Environmental Applications

Current energy demand and the need for environmental stewardship call for transformative technologies that can simultaneously produce clean energy and remediate waste. Biophotoelectrochemical (BPEC) systems are promising platforms that couple the light‐harvesting capability of semiconductor photocatalysts with the catalytic precision of biocatalysts using an electrically addressable electrode. BPEC systems provide tunable reaction pathways, improved scalability, easier product handling, and flexibility in coupling various reactions by modifying the electrode architecture. This review presents a comprehensive discussion of these architectures in BPEC systems, beginning with the fundamental principles of how photoelectrodes and bioelectrodes work. This review then provides a systematic examination of two different electrode architectures: separated electrodes (photoelectrode | bioelectrode) and biohybrid photoelectrodes (biophotoelectrodes). The discussion covers their configurations, working principles, and representative applications such as H ₂ evolution, CO ₂ reduction, N ₂ fixation, pollutant removal, and energy recovery. The review also summarizes key performance metrics and current research trends. By integrating the complementary strengths of photoelectrodes and bioelectrodes, BPEC systems can overcome individual technological limitations and support sustainable energy and environmental applications through self‐biased operation and enhanced product selectivity. Finally, the review discusses the challenges and future directions of advancing BPEC systems into scalable, multifunctional platforms for next‐generation sustainable technologies.