Nanoscale Cu Single-Atom and Carbon-Dot Interfaces in TiO2/PAN Nanofibers for Photothermally Assisted Hydrogen Evolution

Abstract By coupling light-to-heat conversion with photocatalysis, photothermal photocatalysis can enhance solar-energy utilization and accelerate hydrogen-evolution kinetics, showing considerable promise for practical solar-driven hydrogen production. However, the recovery of powder photocatalysts and the insufficient utilization of solar energy remain major barriers to scalable photocatalytic hydrogen production. Herein, a recyclable membrane was constructed by integrating atomically dispersed Cu sites and nitrogen-doped polydopamine-derived carbon dots (NP-CDs) with TiO2 within electrospun polyacrylonitrile (PAN) nanofibers. This architecture combines atomic catalytic sites, NP-CDs/TiO2 nanoscale interfaces, and a recoverable nanofibrous network. Comprehensive analyses of the charge-carrier lifetime, photoresponse, and Gibbs free energy of H adsorption revealed that the introduction of Cu−SAs significantly enhanced the separation efficiency of photogenerated charge carriers and optimized the H* adsorption behavior. Under xenon-lamp irradiation, the Cu−SAs/NP-CDs/TiO2/PAN (TCC-1/PAN) membrane reached 69.5 °C in air after 5 min and 51.6 °C in aqueous solution after 60 min. It delivered a hydrogen evolution rate of 49.61 mmol/m2/h, approximately 10.6 times that of NP-CDs/TiO2/PAN (TC-3/PAN), while retaining 93.4% of its initial activity after seven 4 h cycles. These findings highlight the integration of atomic catalytic sites and nanoscale interfaces within recoverable nanofibrous membranes for photothermally assisted hydrogen evolution.