(111) TiO2-x/Ti3C2: Synergy of active facets, interfacial charge transfer and Ti3+ doping for enhance photocatalytic activity

Abstract The rational design of interface is a key factor for improving the performance of photocatalysts. Herein, a nanocomposite comprised of Ti 3+ doped rutile TiO 2 octahedrons exposing active (111) facets and two-dimensional Ti 3 C 2 sheets was synthesized by a hydrothermal oxidation route and subsequent hydrazine hydrate reduction. The crystallographic facet proportions of TiO 2 can be controlled by NH 4 F as a facet controlling agent. The photocatalytic activity of the TiO 2 /Ti 3 C 2 composite was maximized by completely exposing the active (111) surfaces. The interfacial microstructure between Ti 3 C 2 and TiO 2 can be tuned by the hydrothermal reaction duration. The charge kinetics was substantially steered by the hole trapping effect of 2D Ti 3 C 2 terminated by OH groups. Through the reduction by hydrazine hydrate, Ti 3+ was doped into the bulk of TiO 2 , thereby enabling the photocatalytic activity under visible light. This work opens a new window to the rational design of photocatalysts based on 2D MXene materials.