Eco-friendly preparation of titanium dioxide/carbon nitride nanocomposites for photoelectrocatalytic applications

Titanium dioxide (TiO₂) and its heterostructures are among the most extensively studied materials for photo- and electrocatalytic applications. Optimizing their synthesis remains crucial for enhancing performance and reducing production costs. In this work, we report a simple, eco-friendly method for preparing TiO₂/graphitic carbon nitride (g-C₃N₄) nanocomposites in both powder and thin-film forms. The method takes advantage of the catalytic properties of TiO₂ to significantly lower the temperature required for the formation of g-C₃N₄ from urea, from 600 °C to 300 °C. Incorporating lyophilization prior to thermal treatment results in a ca. 60% increase in the specific surface area. The materials were evaluated for their photo- and electrocatalytic performance. Upon photoactivation at 385 nm, both TiO₂ and TiO₂/g-C₃N₄ powders generate the hydroxyl radical, with lyophilization enhancing radical production fivefold. The lyophilized TiO₂/g-C₃N₄ nanocomposite exhibits 14% higher photocatalytic activity than its TiO₂ counterpart. In electrocatalytic studies, TiO₂/g-C₃N₄ thin films demonstrate a 70 mV lower overpotential for oxygen reduction compared to TiO₂ films. These results highlight the potential of the synthesized nanocomposites for environmental remediation and in energy-related applications such as fuel cell electrodes.