C/Si/core–shell structured TiO₂@TiO_2−x nanocomposites were obtained by combining C, Si and black TiO₂. Amounts of Ti³⁺ and oxygen vacancies in TiO₂@TiO_2−x and the electron transfer among C, Si and TiO₂@TiO_2−x inhibited electron/hole recombination, which resulted in excellent photocatalytic performance.