In situ Ti 3+ -doped TiO 2 crystal in mesoporous nanosheets with dominant (001) facets was prepared by supercritical treatment of the precursor obtained from sol–gel hydrolysis of mixed Ti(n-OC 4 H 9 ) 4 and TiF 4 . This photocatalyst exhibited high activity in synchronical pollutant degradation and water splitting to produce H 2 under visible light irradiation owing to synergistic promoting effects. On one hand, the narrowed energy band gap resulted from Ti 3+ -doping and the high surface area enhanced light harvest and reactant adsorption. On the other hand, the high crystallization degree accelerated electron transfer and thus, inhibited photoelectron–hole recombination. Furthermore, the exposed (001) facets with high surface energy favored the activation of reactant molecules. The photocatalytic degradation of organic pollutants promoted the H 2 production by consuming photogenerated holes, which inhibited their recombination with photoelectrons used for reducing H + during water splitting.