A surface reconstruction route for increasingly improved photocatalytic H₂O₂ production using Sr₂Bi₃Ta₂O₁₁Cl

Photocatalytic hydrogen peroxide (H₂O₂) generation is attractive for the chemical industry and energy production. However, photocatalysts generally deteriorate significantly during use to limit their application. Here we present highly active Sr₂Bi₃Ta₂O₁₁Cl single-crystal nanoplates for conversion of O₂ to H₂O₂ using ambient air with a production rate of ∼3 mmol h^-1 g^-1 (maximum 17.5% photon conversion). Importantly, Sr₂Bi₃Ta₂O₁₁Cl is not only stable during 30 days of H₂O₂ production but also gets consistently activated to increase the H₂O₂ yield by >244%, unlike any other catalyst for H₂O₂ production. Multi-pronged characterization confirms that the synergistic increase in activity originates from in situ surface reconstruction by oxygen-deficient vacancy associate formation that improves (i) surface oxygen adsorption, (ii) sunlight harvesting, and (iii) charge-transfer from the low-valent metal atoms surrounding oxygen vacancies to reactants. The study establishes the prospects of rational defect engineering for realizing non-degrading photocatalysts for realistic H₂O₂ production.