Freestanding Polymer Photoelectrodes for Solar Fuel Generation in Photoelectrochemical Cells

Photoelectrochemical (PEC) cells mimicking natural photosynthesis have emerged as a promising pathway for solar fuel synthesis. While conventional inorganic photoelectrodes have dominated early research, their practical implementation remains constrained by inherent material limitations. Progress has been made recently in freestanding polymer photoelectrodes, presenting a viable alternative approach for PEC cells. In these photoelectrodes, the distinct polymeric architecture, in conjunction with integrated metal catalysts, exhibits notably enhanced PEC performance. The enhancement is attributed to the facilitated photoinduced charge separation and transfer processes occurring within the three-dimensional porous structure. Specifically, in this structure, electrons in the excited states are directly injected from the photosensitizers into the neighboring inorganic catalysts, thereby directly activating the catalytic reactions. In this Perspective, we discuss the recent developments in freestanding polymer photoelectrodes for photoelectrocatalysis, with a particular focus on photoinduced charge transfer dynamics. The Perspective systematically constructs a methodological framework for constructing polymeric photoelectrodes, delineating design principles spanning from molecular-level engineering to macroscopic hierarchical architectures. The established paradigm subsequently supports the development of artificial photosynthetic systems, demonstrating enhanced efficiencies in solar-driven molecular transformations, particularly in water splitting, nitrate-to-ammonia conversion, and CO2 reduction.