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Origin of high-efficiency photoelectrochemical water splitting on hematite/functional nanohybrid metal oxide overlayer photoanode after a low temperature inert gas annealing treatment

DOI: 10.1021/acsomega.8b02444 DOI Help

Authors: Socman Ho-kimura (University College London; University of Macau, Avenida da Universidade) , Benjamin A. D. Williamson (University College London) , Sanjay Sathasivam (University College London) , Savio J. A. Moniz (University College London) , Guanjie He (University College London) , Wenjun Luo (University College London; Ecomaterials and Renewable Energy Research Center (ERERC), NNanjing University) , David O. Scanlon (University College London; Diamond Light Source) , Junwang Tang (University College London) , Ivan P. Parkin (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Omega , VOL 4 , PAGES 1449 - 1459

State: Published (Approved)
Published: January 2019

Abstract: A simplistic and low-cost method that dramatically improves the performance of solution-grown hematite photoanodes for solar-driven water splitting through incorporation of nanohybrid metal oxide overlayers was developed. By heating the α-Fe2O3/SnO2–TiO2 electrode in an inert atmosphere, such as argon or nitrogen, the photocurrent increased to over 2 mA/cm2 at 1.23 V versus a reversible hydrogen electrode, which is 10 times higher than that of pure hematite under 1 sun (100 mW/cm2, AM 1.5G) light illumination. For the first time, we found a significant morphological difference between argon and nitrogen gas heat-treated hematite films and discussed the consequences for photoresponse. The origin for the enhancement, probed via theoretical modeling, stems from the facile incorporation of low formation energy dopants into the Fe2O3 layer at the interface of the metal oxide nanohybrid overlayer, which decreases recombination by increasing the electrical conductivity of Fe2O3. These dopants diffuse from the overlayer into the α-Fe2O3 layer readily under inert gas heat treatment. This simple yet effective strategy could be applied to other dopants to increase hematite performance for solar energy conversion applications.

Journal Keywords: Catalysts; Heat treatment; Nanocomposites; Nanoparticles

Subject Areas: Chemistry, Energy


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