Influence of various sacrificial reagents on congo red degradation and H₂O₂ production based on heteroanionic titanium oxycarbide photocatalyst and its mechanism

Combining a rational design strategy with a simple synthetic method to produce an eco-friendly material presents a unique challenge in photocatalysis technology. This work reports the successful synthesis of a heteroanionic titanium oxycarbide photocatalyst—TiO_0.25C_0.75 (TiOC) via a solid-state reaction and employed for the decomposition of Congo red (CR) and H₂O₂ generation from water under visible light radiation. Initially, TiOC demonstrated a moderate CR degradation efficiency of 54% (1 g/L) in 120 min and evolved a minimal amount of H₂O₂ after 90 min (2 mmol) and 120 min (10 mmol) of light exposure. This clearly indicates that the localization of hybridization of O-2p and C-2p orbitals and a more positive conduction band edge (CB) of TiOC lead to reduced carrier mobility and, consequently, high recombination of photogenerated charge carriers. Therefore, sacrificial reagents such as H₂O₂ and isopropyl alcohol (ISA) were employed to improve CR removal and H₂O₂ evolution rate, resulting in 70% and 21.5 mmol (120 min), respectively.