Coupled Photon Transport and Interfacial Charge Utilization in ACT/g-PAN for Photocatalytic CO₂ Reduction

Integrating microscopic catalyst design with macroscopic photophysical reaction engineering is important for improving solar-driven CO₂ reduction. However, previous studies have largely focused on the molecular-level optimization of catalysts, whereas the coupled effects of macroscopic reaction parameters have been less systematically investigated. This knowledge gap may limit the rational optimization and practical development of photocatalytic systems. Here, we investigate the effects of Ag/Cu-TiO₂/g-PAN catalyst dosage, incident light wavelength, and plasmon-related photothermal effects on photocatalytic activity under near-ambient conditions. By evaluating the optical transmittance and kinetic stability of the catalyst suspension, we identify reaction conditions that balance light penetration with the number of accessible active sites. The results show that Ag/Cu-TiO₂/g-PAN exhibits a broadband photocatalytic response. However, the temperature-dependent results suggest that interfacial temperature elevation associated with plasmonic heating may decrease CO₂ adsorption and thereby limit the overall catalytic efficiency. This work provides insight into the coupling between photon transport and charge-carrier dynamics and offers guidance for the rational design of slurry-based photocatalytic CO₂-reduction systems.