Al-N co-doped to reduce Ti3+ concentration to suppress charge recombination of polyhedral SrTiO3 for efficient photocatalytic CO2 reduction

The presence of the carrier recombination center Ti3+ and the wider bandgap in SrTiO3(STO) make it less efficient for photogenerated carriers and sunlight, which slows down its photocatalytic CO2 reduction rate severely. Based on this, the molten salt method was employed to prepare Al3+ and N3- co-doped polyhedral STO. A series of photoelectrochemical performance tests showed that the photogenerated carriers separation and transport efficiencies of the Al3+ and N3- co-doped polyhedral STO were significantly improved, and the doping of Al3+ and N3- also enhanced the light absorption capacity of the polyhedral STO. The rate of CO2 reduction to CO in the Al3+ and N3- co-doped polyhedral STO is more than twice that of the original polyhedral STO, reaching 3.82 mu mol center dot g- 1 center dot h- 1, and significantly higher than the polyhedral STO doped with Al3+ or N3- . The photodeposition experiments demonstrated that the elementally doped polyhedral STO maintained an anisotropic carrier transport mode. The introduction of Al3+ ions diminishes the recombination center of Ti3+. Additionally, N3- doping introduces impurity energy levels within the energy band of polyhedral STO, which enhances its light-absorbing capacity. This synergistic effect of ionic doping and crystal facet engineering allows the polyhedral STO to possess an efficient carrier-directed transport mode and expand its light absorption range, significantly improving its photocatalytic CO2 reduction activity.