<scp>Iridium‐cobalt</scp> alloy nanotubes as a bifunctional electrocatalyst for <scp>pH‐universal</scp> overall water splitting
Yoon-Kyeong Kim, Areum Yu, Youngmi Lee
Abstract
Abstract Bimetallic Ir x Co 1− x alloy nanotubes ( x = 0.25, 0.50 and 0.75, the atomic ratios of Ir precursor out of the total metal precursor) were prepared via the thermal H 2 ‐reduction of Ir x Co 1− x O y nanotubes which were synthesized by electrospinning and post calcination. Ir and Co atoms were well mixed to form the alloy in Ir x Co 1− x nanotubes. Their phase structures were different depending on the composition ratios. Ir 0.75 Co 0.25 and Ir 0.50 Co 0.50 had Ir fcc phase where some Ir atoms were substituted with Co. In contrast, Ir 0.25 Co 0.75 was in Ir‐substituting Co hcp phase. Among the Ir x Co 1− x alloy nanotubes, Ir 0.50 Co 0.50 showed the highest catalytic activity for overall electrochemical water splitting in acidic, neutral, and alkaline conditions, better than pure metallic Ir and Co counterparts. The activity and stability of Ir 0.50 Co 0.50 nanotubes for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) were superior to commercial Ir/C and Pt/C, respectively.