Gradient Si- and Ti-doped Fe2O3 hierarchical homojunction photoanode for efficient solar water splitting: Effect of facile microwave-assisted growth of Si-FeOOH on Ti-FeOOH nanocorals

The construction of a homojunction is an effective approach for addressing issues such as slow charge separation and charge-transfer kinetics in photoanodes. In the present work, we designed a gradient Si-and Ti-doped Fe2O3 homojunction photoanode to improve the photoelectrochemical (PEC) performance of a Ti-doped Fe2O3 photoanode. Ti-FeOOH nanocorals were synthesized using a hydrothermal process, and Si-FeOOH was grown on Ti-FeOOH nanocorals using a rapid and facile microwave assisted (MW) technique. By varying the MW irradiation time, the thickness of the Si/Ti:Fe2O3 photoanode was adjusted and an optimized 3-Si/Ti:Fe2O3 photoelectrode was achieved with a significantly enhanced photocurrent density (1.37 mA cm-2 at 1.23 V vs. RHE) and a cathodic shift of the onset potential (150 mV) compared with that of bare Ti-Fe2O3. This enhanced PEC performance can be ascribed to homojunction formation and Si gradient doping. The Si dopant increased the donor concentration and the formation of a homojunction improved the intrinsic built-in electric field, thereby promoting charge separation and charge transfer. Furthermore, the as-formed homojunction passivated the surface trapping states, consequently improving the charge transfer efficiency (60% at 1.23 VRHE) at the photoanode/electrolyte interface. These findings could pave the way for the microwave-assisted fabrication of diverse efficient homojunction photoanodes for PEC water splitting applications.(c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

The study presents the design and synthesis of a gradient Si- and Ti-doped Fe2O3 homojunction photoanode to enhance the photoelectrochemical (PEC) performance. The Si-FeOOH layer was grown on Ti-FeOOH nanocorals using a microwave-assisted technique. The optimized 3-Si/Ti:Fe2O3 photoelectrode exhibited significantly improved photocurrent density and onset potential compared to bare Ti-Fe2O3. The enhanced PEC performance can be attributed to homojunction formation and Si gradient doping, which promoted charge separation and charge transfer.