Visible light absorption of (Fe,C/N) co-doped NaTaO_3: DFT+U

The effects of Fe-C/N co-doping on the electronic and optical properties of NaTaO₃ are studied with density functional theory. Our calculations indicate that mono-doped and co-doped sodium tantalate are both thermodynamically stable. The co-doping sodium tantalate can reduce the energy band gap to a greater degree due to the synergistic effects of Fe and C (N) atoms than mono-doping sodium tantalate, and has a larger optical absorption of the whole visible spectrum. The band alignments for the doped NaTaO₃ are well positioned for the feasibility of hydrogen production by water splitting. The Fe-C co-doping can enhance the absorption of the visible light and its photocatalytic activity more than Fe-N co-doping due to the different locations of impurity energy levels originating from their p-d hybridization effect.