Bifunctional In³⁺ Doping toward Defect Engineering in SrTiO₃ for Solar Water Splitting

Area of Science:

• Materials Science
• Photocatalysis
• Solar Energy Conversion

Background:

• Defect engineering in strontium titanate (SrTiO3) is crucial for solar water splitting.
• Aluminum (Al3+) doping influences SrTiO3 but causes uneven structural relaxation, impacting catalytic activity.
• Al2O3 crucibles complicate defect optimization in SrTiO3.

Purpose of the Study:

• To enhance photocatalytic performance of SrTiO3 for solar water splitting.
• To investigate the role of Indium (In3+) doping in SrTiO3 crystal defect engineering.
• To mitigate the negative effects of Al3+ on structural relaxation and defect states.

Main Methods:

• Introduction of In3+ into SrTiO3 crystals.
• Utilizing density functional theory (DFT) calculations.
• Conducting carrier behavior studies.
• Analyzing structural relaxation and defect charge concentration.

Main Results:

• In3+ preferentially occupies B sites in SrTiO3, outcompeting Al3+.
• In3+ doping regulates defect charges and reduces Al3+-induced structural relaxation, creating shallow-state defects.
• In3+ incorporation prevents perovskite Sr2+ precipitation.
• Optimized In3+-doped SrTiO3 shows high H2 (1.40 mmol·h-1) and O2 (0.69 mmol·h-1) evolution rates.
• Achieved apparent quantum yield (AQY) of 82.36% at 365 nm and solar-to-hydrogen (STH) efficiency of 0.54%.

Conclusions:

• In3+ doping is an effective strategy for defect engineering in SrTiO3 for solar water splitting.
• In3+ ions improve structural stability and photocatalytic activity of SrTiO3.
• The bifunctional role of In3+ in regulating defects and structural relaxation is key to enhanced performance.