Low onset potential for oxygen evolution reaction on hematite electrodes processed with He plasma irradiation

In this study, we investigated the effects of helium (He) plasma irradiation and thermal treatment on the morphology, the surface characteristics, and the photoelectrochemical performance of bulk iron (Fe) sheets. After processing, all samples consisted mainly of an alfa-Fe2 O3 surface. Helium plasma irradiation resulted in a cathodic shift in the onset potential of the photocurrent from 1.16 V RHE (no pretreatment) to 0.57 V RHE (plasma exposure at 660 degrees Celcius), where V RHE represents the potential versus reversible hydrogen electrode (RHE). An increase in the surface roughness and a smaller amount of hydroxyl or oxygen vacancies at the surface after photoelectrochemical measurement are related to the decrease of the onset potential. The results show that He plasma irradiation does not only modify the surface morphology, but also affects the functional properties of the materials.