Structural Insight on Defect-Rich Tin Oxide for Smart Band Alignment Engineering and Tunable Visible-Light-Driven...

Area of Science:

• Materials Science
• Photocatalysis
• Nanotechnology

Background:

• Tin oxides (SnO) are promising photocatalysts.
• Controlling defect chemistry is crucial for enhancing photocatalytic activity.
• Understanding structure-property relationships is key for catalyst design.

Purpose of the Study:

• To synthesize defect-rich tin oxides (SnO) with tunable Sn²⁺/Sn⁴⁺ ratios.
• To investigate the impact of local structure, non-stoichiometry, and defects on band gap and band edge potentials.
• To evaluate the photocatalytic hydrogen evolution performance under visible light.

Main Methods:

• Synthesis of defect-rich tin oxides with varying Sn²⁺/Sn⁴⁺ ratios.
• Characterization using X-ray photoelectron spectroscopy, Mossbauer, and electron spin resonance.
• Photocatalytic activity evaluation via water splitting for hydrogen production under visible light.
• Theoretical calculations to correlate structure, electronic properties, and activity.

Main Results:

• Tunable Sn²⁺/Sn⁴⁺ ratios and defect chemistry (oxygen vacancies, interstitial tin) were achieved.
• Optimal photocatalytic H₂ production rate reached 58.6 μmol·g^-1·h^-1.
• Higher Sn²⁺/Sn⁴⁺ ratios led to more negative band edge potentials, enhancing hydrogen production.
• Activity decreased with increasing synthesis temperature.

Conclusions:

• Non-stoichiometric SnO with high Sn²⁺ content, hydroxyl groups, and negative conduction band potentials are effective for visible light harvesting and water splitting.
• Regulating internal electronic structure and surface defects offers a novel strategy for developing efficient photocatalysts.
• The study clarifies the relationship between crystal structure, electronic properties, and photocatalytic performance.