ABSTRACT

Hematite (a-Fe2O3), with a suitable bandgap of 2.2 eV, is an ideal photoanode material to convert solar light into hydrogen fuel via photoelectrochemical (PEC) water splitting. However, poor charge separation efficiency in the bulk and slow oxygen evolution kinetics at the Fe2O3/electrolyte interface have restricted its PEC performance to date. Here, we designed and fabricated a nanostructured WO3/Fe2O3 thin film photoanode by electrospray technique to promote bulk charge separation of Fe2O3. An Co(OH)x nanolayer was further coated onto the surface by a solution-based chemisorption method to improve its oxygen evolution kinetics. We found the deposition amount ratio of WO3 versus Fe2O3 and substrate temperature greatly influenced the PEC performance of WO3/Fe2O3 photoanode. With optimal deposition amount ratio of 1:1 and substrate temperature of 400 oC, the WO3/Fe2O3 photoanode shows a photocurrent of 0.32 mA cm-2 at 1.23 VRHE which is more than 30-times higher than pure Fe2O3 film. Its photocurrent is further increased to 0.62 mA cm-2 after modified with Co(OH)x nanolayer and an obvious cathodic onset potential shift by about 160 mV is observed. The results show that this enhanced photoactivity is attributed to simultaneously improved charge carriers separation efficiency at the WO3/Fe2O3 heterojunction interface and accelerated oxygen evolution kinetics at the surface.

 2019-Sustainable Energy Fuels-SCI.pdf