Recycling Carbon Fiber-Reinforced Polymers (CFRPs) to Construct CFs/TiO₂ Nanotexture with Efficient Interface Charge Transfer for Stimulating Photocatalytic Hydrogen Production

In this work, carbon fiber-reinforced polymer (CFRP) waste-derived carbon fibers (CFs) coupled with TiO₂ for photocatalytic hydrogen production have been investigated. The CFs were found to be promising for enhancing visible light absorption and preventing photoinduced charge carrier recombination. The role of interface interaction and morphology was further investigated by synthesizing nanocomposites through physical mixing (CFs/TiO₂) and sol-gel methods (CFs/TiO₂-S). The optimized 3CFs/TiO₂ produces 2.87 times more hydrogen than using only TiO₂. This noticeable enhancement was due to efficient charge separation in the presence of CFs with high visible light absorption. Comparatively, the CFs/TiO₂-S nanotexture produced H₂ at 2268.4 μmol g^-1 h^-1, which is 6-12 fold greater than that for CFs/TiO₂ and pristine TiO₂ samples. Using the sol-gel approach, TiO₂ was effectively attached over the entire surface of CFs, enabling good interface interaction and efficient charge carrier separation, resulting in significantly enhanced H₂ production. Among the various operating parameters, glycerol as a sacrificial reagent was promising to improve H₂ yield, whereas it has a lower photostability than methanol after five consecutive cycles. The highest AQY of 26.3% for H₂ production was obtained with 150 mg of catalyst loading under low-intensity light irradiation. This study introduces a new technique to recycle solid waste CFRPs to produce CF-based composites that might be advantageous to boost performance in solar energy-related applications.