Solution chemistry back-contact FTO/hematite interface engineering for efficient photocatalytic water oxidation

Abstract

This work describes a simple yet powerful scalable solution chemistry strategy to create back-contact rich interfaces between substrates such as commercial transparent conducting fluorine-doped tin oxide coated glass (FTO) and photoactive thin films such as hematite for low-cost water oxidation reaction. High-resolution electron microscopy (SEM, TEM, STEM), atomic force microscopy (AFM), elemental chemical mapping (EELS, EDS) and photoelectrochemical (PEC) investigations reveal that the mechanical stress, lattice mismatch, electron energy barrier, and voids between FTO and hematite at the back-contact interface as well as short-circuit and detrimental reaction between FTO and the electrolyte can be alleviated by engineering the chemical composition of the precursor solutions, thus increasing the overall efficiency of these low-cost photoanodes for water oxidation reaction for a clean and sustainable generation of hydrogen from PEC water-splitting. These findings are of significant importance to improve the charge collection efficiency by minimizing electron-hole recombination observed at back-contact interfaces and grain boundaries in mesoporous electrodes, thus improving the overall efficiency and scalability of low-cost PEC water splitting devices. To minimize photogenerated carrier losses and improve overall PEC efficiency, the back-contact FTO-photocatalyst interface is engineered using a simple and scalable solution chemistry process.