Photocatalytic production of H2O2 over rutile TiO2 supported with Pd nanoparticles

Abstract

Hydrogen peroxide is a valuable chemical, which is commonly employed in environmental application for advanced oxidation processes and in energy application for fuel cells. Local production of H₂O₂ directly at sites of its consumption can eliminate risks and costs associated with transportation of concentrated H₂O₂ solutions. In this study, we investigated the ability of rutile or anatase TiO₂ modified with Pd nanoparticles to produce hydrogen peroxide via photocatalytic oxygen reduction. Surface modification of TiO₂ with Pd cocatalyst allowed H₂O₂ generation in both deionized water and water-methanol solution under UV-LED irradiation. Rutile TiO₂ supported with Pd nanoparticles exhibited boosted photocatalytic activity in H₂O₂ formation compared to anatase-based photocatalyst. H₂O₂ was shown to predominantly form through the pathway of oxygen reduction, and observed difference in activity was attributed to different positions of energy bands in rutile and anatase phases. Methanol as an efficient electron donor substantially increased the amount of evolved H₂O₂. Rate constants of H₂O₂ generation over Pd-decorated rutile TiO₂ were 1.7 μmol min⁻¹ in deionized water and 7.4 μmol min⁻¹ in water-methanol solution (10 vol%). This study reveals the potential of rutile for design of efficient heterostructured composites with other narrow-band semiconductors for photocatalytic generation of H₂O₂ under solar light.