Multiple functions of anthraquinone complexed with TiO2 for enhanced solar hydrogen peroxide synthesis

Abstract

Solar hydrogen peroxide (H2O2) production is recognized as an environmentally friendly, sustainable, and cost-effective process, requiring only water, oxygen, and sunlight. Titanium dioxide (TiO2), known for its high stability and low material cost, is commonly used as a photocatalyst for H2O2 production. However, its limited absorption of solar light, particularly in the visible spectrum, and easy decomposition of H2O2 significantly hinder the production efficiency. Moreover, it often requires costly co-catalysts such as noble metals or graphene to achieve high efficiency. Herein, we demonstrate that the photocatalytic performance of TiO2 for H2O2 production under solar light irradiation can be substantially improved by complexing anthraquinone (AQ). The AQ/TiO2 complex achieved an impressive H2O2 production efficiency in the presence of 2-propanol as an electron donor under simulated solar light irradiation. Comprehensive experimental analyses revealed that AQ functions both as a ligand-to-metal charge transfer (LMCT) sensitizer, enhancing solar light absorption and a co-catalyst, facilitating the reduction of oxygen to H2O2. In addition, the presence of AQ on the TiO2 surface markedly reduced the decomposition of in-situ formed H2O2. This study presents an effective strategy for selective H2O2 production usin