Introducing High‐Valence Iridium Single Atoms into Bimetal Phosphides toward High‐Efficiency Oxygen Evolution and Overall Water Splitting
Niuwa Yang, Shaonan Tian, Yongjun Feng, Zhenya Hu, Hui Liu, Xinlong Tian, Lin Xu, Chaoquan Hu, Jun Yang
Abstract
Abstract Single atoms are superior electrocatalysts having high atomic utilization and amazing activity for water oxidation and splitting. Herein, this work reports a thermal reduction method to introduce high‐valence iridium (Ir) single atoms into bimetal phosphide (FeNiP) nanoparticles toward high‐efficiency oxygen evolution reaction (OER) and overall water splitting. The presence of high‐valence single Ir atoms (Ir 4+ ) and their synergistic interaction with Ni 3+ species as well as the disproportionation of Ni 3+ assisted by Fe collectively contribute to the exceptional OER performance. In specific, at appropriate Ir/Ni and Fe/Ni ratios, the as‐prepared Ir‐doped FeNiP (Ir 25 ‐Fe 16 Ni 100 P 64 ) nanoparticles at a mass loading of only 35 µg cm −2 show the overpotential as low as 232 mV at 10 mA cm −2 and activity as high as 1.86 A mg −1 at 1.5 V versus RHE for OER in 1.0 m KOH. Computational simulations confirm the vital role of high‐valence Ir to weaken the adsorption of OER intermediates, favorable for accelerating OER kinetics. Impressively, a Pt/C||Ir 25 ‐Fe 16 Ni 100 P 64 two‐electrode alkaline electrolyzer affords a current density of 10 mA cm −2 at a low cell voltage of 1.42 V, along with satisfied stability. An AA battery with a nominal voltage of 1.5 V can drive overall water splitting with obvious bubbles released.