Electron flow mechanisms in the coupled photocatalytic-microbial systems

The coupled photocatalytic-microbial systems (CPMSs) integrate photocatalysts with microorganisms through various coupling strategies, offering a promising platform for water treatment and energy/chemical production. The biotic-abiotic communication bridge-the electron flow mechanism-plays a critical role in enhancing the energy conversion efficiency and pollutant removal capacity in CPMSs. However, mainstream CPMSs configurations still lack full elucidation of the electron flow mechanisms. Investigations into CPMSs have now emerged as a major research focus, and comprehensive understanding of entire electron flow processes will advance their practical development. Currently, no systematic literature comprehensively summarizes the electron flow process within CPMSs. Thus, this review aims to deepen understanding of full-process electron flow mechanisms in CPMSs. It focuses on three fundamental stages characteristic of CPMSs: electron generation, electron transfer, and electron utilization. By integrating interdisciplinary perspectives, this review aims to establish a conceptual framework for understanding electron flow mechanisms in CPMSs, thereby enhancing mechanistic comprehension and realizing the maximum capabilities of CPMSs. Elucidating these microscopic mechanisms provides crucial guidance for designing efficient, low-energy wastewater treatment processes, achieving solar-driven carbon neutrality technologies, and developing sustainable chemical synthesis strategies.