Detonated growth and functionalization of iron (III) oxyhydroxide nanorod array templates via microwave-assisted synthesis for photoelectrochemical water splitting

Abstract

In this study, we describe for the first time the detonated ultrafast growth and functionalization of Iron (III) oxyhydroxide (FeOOH) nanorod array templates on a fluorine-doped tin oxide (FTO) substrate using a specially designed microwave-assisted cost-effective synthesis route. The rapid recrystallization and polycondensation in microwave-assisted synthesis (MAS) led to the controlled growth of ferric-hydroxide Fe(OH)3 from the iron-hydroxo complex Fe(H2O)3(OH)3 formed from hydrolyzed FeCl3. Further, the dependence of a number of MAS cycles on the growth and evolution of β-FeOOH nanorod array templated photoanode was examined by high-resolution scanning electron microscopy. The formation mechanism with morphology-controlled FeOOH nanostructure was well discussed and verified. Further, high-temperature quenching (HTQ) transformed MAS akaganeite into hematite, and Sn4+ diffused from FTO substrate. Due to the synergistic impact of MAS growth and Sn4+ diffusion in the α-Fe2O3 nanostructure, the optimum FTO/Fe2O3-1 photoanode achieved the highest photocurrent density (0.854 mA cm−2 at 1.23 V vs. RHE) related with other studied samples. The charge-transfer mechanisms in microwave-assisted Sn4+-diffused α-Fe2O3 nanostructure photoanodes are also investigated. Additionally, the surface-modified FTO/Fe2O3-1 photoanode exhibited the 91 and 180 μmol of oxygen and hydrogen evolution during photoelectrochemical water splitting, respectively. This work opens a sustainable and feasible strategy for designing and regulating high-efficient novel functional photoanode materials for water splitting.