Laminated Hybrid Junction of Sulfur-Doped TiO₂ and a Carbon Substrate Derived from Ti₃C₂ MXenes: Toward Highly Visible Light-Driven Photocatalytic Hydrogen Evolution

TiO₂ is an ideal photocatalyst candidate except for its large bandgap and fast charge recombination. A novel laminated junction composed of defect-controlled and sulfur-doped TiO₂ with carbon substrate (LDC-S-TiO₂/C) is synthesized using the 2D transition metal carbides (MXenes) as a template to enhance light absorption and improve charge separation. The prepared LDC-S-TiO₂/C catalyst delivers a high photocatalytic H₂ evolution rate of 333 µmol g⁻¹ h⁻¹ with a high apparent quantum yield of 7.36% at 400 nm and it is also active even at 600 nm, resulting into a 48 time activity compared with L-TiO₂/C under visible light irradiation. Further theoretical modeling calculation indicates that such novel approach also reduces activation energy of hydrogen production apart from broadening the absorption wavelength, facilitating charge separation, and creating a large surface area substrate. This synergic effect can also be applied to other photocatalysts' modification. The study provides a novel approach for synthesis defective metal oxides based hybrids and broaden the applications of MXene family.