Perylene-3,4,9,10-tetracarboxylic acid accelerated light-driven water oxidation on ultrathin indium oxide porous sheets

Engineering the organic/inorganic nanocomposites by taking advantage of the high electrical conductivity of the inorganic semiconductors and the structure flexibility of the organic semiconductors (OSCs) provides chances to understand the structural and electronic contributions that give rise to increased activities, which is the imperious demand for methodical design of next-generation of oxygen evolution photocatalysts. Herein, perylene-3,4,9,10-tetracarboxylic acid (PTCAD) bonded porous In2O3 nanosheets, PTCAD/In2O3 NSs, were fabricated to elucidate the performance of OSCs in light harvesting and charge separation toward photo-driven oxygen evolution reaction (OER). PTCAD coupled strongly to the conduction band (CB) of In2O3 NS and type-II energy alignment was constructed between these two organic-inorganic components. Consequently, upon excitation, electrons injected smoothly from PTCAD to In2O3 NS, leaving holes behind to perform water oxidation, which results in accelerated charge separation and transportation. Associated with the large specific area, high-speed electron transmission channels, abundant oxygen vacancies and active sites provided by the In2O3 NS, the PTCAD/In2O3 composites demonstrated highly reduced band gap (BG), boosted and stable photocurrent, as well as largely reduced overpotential, suggesting promises for broadband-light-triggered OER. In addition to the synergistic effects in promoting charge separation and inhibiting electron-hole recombination, the pi-conjugated molecule, PTCAD, played a role of manipulating the lattice plane of the In2O3 nanostructure without disturbing its porous 2D structure, providing another potential approach for enhancement of catalytic activity by regulating the crystal faces. Importantly, water oxidation over PTCAD/In2O3 NSs is indeed a proton-coupled electron transfer (PCET) processes, a key process for charge separation and water oxidation, which is significantly promoted by PTCAD. Ultimately, the photo-catalytic oxygen evolution yield enhanced greatly at the presence of PTCAD, indicating that our findings may provide clues for development of organic/inorganic hybrid semi-conducting photocatalysts for solar fuels generation.