Gallium Oxide Nanofibers for Hydrogen Evolution and Oxygen Reduction

An effective, cost-efficient catalyst material that can replace platinum as electrode material in fuel cell has become the focus point of non-fossil fuel based alternate energy systems. Transition/post-transition metal oxide based catalyst development is now the thrust area in the above-mentioned context for efficient energy conversions, especially oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Here, for the first time, application of electrospun β-gallium oxide (β-Ga2O3) nanofibers, a post-transition metal oxide, as an efficient bifunctional catalyst material is reported. These nanofibers are highly porous (specific surface area ∼100–300 m2/g) and exhibit a mesoporous architecture (pore size ∼1.5–2 nm) which facilitates better ion transport through the spongy morphology of individual nanofiber. The fabricated β-Ga2O3 nanofibers performed at par with the Pt/C catalyst, like for ORR the onset potential was 0.84 V (vs RHE) and for HER, although the onset potential was −0.34 V (vs RHE), the current density was visibly better than the latter catalyst. This catalyst also performed much better in methanol tolerance test and was near similar in current retention for 6 h, as measured in chronoamperometry. This performance was solely attributed to the large surface area and unique morphology presented by the material, via a rather simple fabrication technique, without addition of any dopant material.