Ir/Ni–NiO/CNT composites as effective electrocatalysts for hydrogen oxidation

Abstract

Developing highly efficient non-Pt hydrogen oxidation (HOR) catalysts for use in alkaline solution is very important for anion-exchange membrane hydrogen–oxygen fuel cells. Herein, Ir/Ni–NiO/CNT composite catalysts were designed and prepared, in which carbon nanotubes (CNTs) were used as the support and iridium nanoparticles were anchored on the surface of Ni–NiO. In alkaline media, the as-prepared Ir/Ni–NiO/CNT catalyst exhibited excellent catalytic performance with a mass activity of 1.59 mA μg_Ir⁻¹ for HOR, which is superior to that of Ir/CNT and even commercial Pt/C catalysts. Experimental and theoretical calculation studies showed that the presence of Ni–NiO weakened the hydrogen binding energy on Ir sites, which facilitated the Volmer step for HOR and thus improved the catalytic activity.