Selection on antimony-doped tin oxide (ATO) as an efficient support for iridium-based oxygen evolution reaction (OER) catalyst in acidic media

Reducing the iridium content while preserving high OER activity is an important prerequisite for the progress of inexpensive anodic water splitting electrocatalysts in low pH medium. Here we report the effects of bulk and surface structures of antimony doped tin oxide (ATO) supports on the ATO supported Ir-based electrocatalyst's activity for oxygen evolution reaction (OER) in acidic media. Ability of the ATO supports to anchor the Ir nanoparticles, measured as the fraction of Ir species from reaction bath landed on ATO support (conversion efficiency; ηc), is found to be strongly dependent on its surface chemistry, characterized in terms of presence of surface oxygen groups (Osurface). Both Osurface content and electronic conductivity of ATOs show strong influence on OER activity. In general, high conductivity and low Osurface content are preferred for high OER activity, though low Osurface may compromise ηc. The optimal catalyst demonstrates superior OER activity of 777 A g−1, 2.5 times that of the state-of-the-art commercial catalyst at 1.65 V vs. RHE. Further, the synthesized catalysts exhibit durability comparable to that of the commercial counterpart.