Double-Sided Illuminated Electrospun PAN TiO2-Cu2O Membranes for Enhanced CO2 Photoreduction to Methanol

Photocatalytic reduction of CO2 into value-added chemicals offers a sustainable route to mitigate greenhouse gas emissions while producing renewable fuels. However, conventional TiO2-based systems suffer from limited visible-light activity and inefficient reactor configurations. Here, we developed electrospun polyacrylonitrile (PAN) membranes embedded with TiO2-Cu2O heterojunction nanoparticles and integrated them into a custom crossflow photocatalytic membrane reactor. The reactor employed bifacial illumination using a solar simulator (front) and a xenon/mercury lamp (back), each calibrated to 1 Sun (100 mW·cm−2). Membrane morphology was characterized by SEM, and chemical composition was confirmed by XPS. Photocatalytic performance was evaluated in CO2-saturated 0.5 M potassium bicarbonate solution under continuous flow. The PAN/ TiO2-Cu2O membrane exhibited a methanol production rate of approximately 300 μmol·g−1·h−1 under dual-light illumination, outperforming single illumination, PAN-TiO2, and PAN controls. Enhanced activity is attributed to extended visible-light absorption, improved charge separation at the TiO2-Cu2O heterojunction, and optimized photon flux through bifacial illumination. The electrospun architecture provided high surface area and porosity, facilitating CO2 adsorption and catalyst dispersion. Combining heterojunction engineering with bifacial reactor design significantly improves solar-driven CO2 conversion. This approach offers a scalable pathway for integrating photocatalysis and membrane technology into sustainable fuel synthesis.