Enhanced visible light response and cytocompatibility of TiO₂–TiC shell–core structured S-scheme photocatalyst

To enhance the visible light response of titanium dioxide (TiO₂), titanium carbide (TiC) nanoparticles (NPs) were thermally treated in carbon powder, effectively overcoming the challenges associated with conventional doping methods. During the treatment, a TiO₂ thin shell with oxygen vacancies (OVs) formed around the TiC NPs, creating a shell–core structure S-scheme photocatalyst. Transmission electron microscopy (TEM) and ultraviolet–visible (UV–vis) spectroscopy confirmed the successful formation of the TiO₂ shell. By optimizing the shell thickness, the TiO₂–TiC shell–core structure achieved an ideal shell–core ratio, resulting in strong visible light absorption (400–800 nm), and the degradation rate constant of Rhodamine B (RhB) of sample cHT500 reached 0.0687 min⁻¹, which is 20.8 times higher than that of pristine TiO₂ (0.0033 min⁻¹) under visible-light-driven photocatalysis. In addition, cytocompatibility tests showed that sample cHT500 exhibits favorable cell viability, which is comparable to that of TiO₂ nanoparticles, and thus remarkably mitigates the poor biocompatibility inherent to TiC, making them promising candidates for biomedical and photocatalytic applications.