Boosting photocatalytic H2O2 production in pure water over a plasmonic photocatalyst with polyethylenimine modification

Abstract

Solar-powered photocatalytic H₂O₂ production is promising for its advantages of being safe, portable, green and energy efficient but achieving high efficiency is challenging, especially under pure water and air conditions. Herein, a titanium dioxide/polyethylenimine/Ag nanoparticle (abbreviated as TiO₂/PEI/AgNP) photocatalyst is prepared in a facile manner by electrostatic assembly and in situ polymer reduction, which combines local surface plasmon resonance and photocatalysis to exhibit ultra-fast H₂O₂ production activity in pure water. The obtained photocatalysts exhibit an unexpectedly high H₂O₂ production activity (1605 μmol g⁻¹ h⁻¹ under simulated sunlight) in air and pure water, which is 24-fold higher than that of pristine rutile TiO₂. The TiO₂/PEI/AgNP composites simultaneously optimize three parts of photocatalytic H₂O₂ production: (i) improved charge separation, (ii) captured H⁺ faster and (iii) blocked direct contact of H₂O₂ and the catalyst. Experimental data and density functional theory calculations prove that the AgNP component can rapidly conduct high-energy electrons generated by themselves and photogenerated electrons generated by TiO₂ to reactants. The PEI component can capture H⁺ from pure water faster to promote the superoxide radical to generate H₂O₂ through the proton coupling reaction and block direct contact of H₂O₂ and the TiO₂ component. This work establishes a paradigm for the rational design of efficient plasmonic photocatalysts via self-assembly and in situ reduction technologies toward H₂O₂ production in pure water and air.