Molecular–Polymeric Hybrid Photocathodes for CO ₂ Reduction: A Modular Approach to Sustainable Photoelectrocatalysis

The development of efficient and sustainable photocathodes is central to advancing photoelectrocatalytic CO 2 reduction. Here, we report CP/PPy/Re–Ru, a hybrid molecular–polymeric photocathode prepared in a simple two‐step process by depositing catalytically active Re–Ru complexes onto a polypyrrole backbone on carbon paper. The approach is resource‐efficient and modular. Under photoelectrocatalytic conditions at −1.4 V versus normal hydrogen electrode (NHE), the material achieved ∼15 µmol CO formation within 1 h at Faradaic efficiencies of 60%–70%. Continuous CO evolution was maintained for up to 7 h even in membrane‐free operation, yielding ∼90 µmol CO while avoiding the use of polyfluoroalkyl substance (PFAS)‐based membranes. Reusability was further demonstrated across multiple cycles, confirming the robustness of the concept. Postreaction analyses indicated structural changes, pointing to opportunities for future optimization of long‐term stability. Overall, CP/PPy/Re–Ru provides a versatile and sustainable platform that combines straightforward preparation with promising activity and adaptability, offering a valuable foundation for next‐generation CO 2 reduction technologies.