Issue 37, 2022

Iridium nanohollows with porous walls for acidic water splitting

Abstract

Engineering iridium (Ir)-based electrocatalysts towards high activity and satisfactory durability for the oxygen evolution reaction (OER) in acidic media has been long pursued to commercialize proton exchange membrane-based electrolyzers. Here we report a novel class of Ir porous nanohollows (p-NHs) with tunable wall thickness, which electrocatalyze acidic OER with much enhanced performance relative to conventional Ir nanoparticles. The p-NH structure is deliberately-tailored via a facile hydrothermal approach, in which the initially-formed solid Ir spheres were in situ etched via the Kirkendall effect. At an overpotential of 300 mV, the Ir p-NH catalyst delivers a mass activity of 1.75 A mgIr−1, which is 6.25 and 3.20 times higher than those of commercial Ir/C and control Ir solid nanosphere catalysts, respectively. Ir p-NHs as an anode enable voltages of 1.50 V and 1.59 V at 10 and 100 mA cm−2, respectively, for acidic water splitting. We explore how porosity energetically promotes OER activity of Ir-based catalysts using density functional theory (DFT) calculations, which reveal that the adsorption of *OOH and thus OER activity can be described by the generalized coordination number of surface Ir sites. Our findings offer new insights into the rational design of highly-open Ir-based nanostructures for efficient OER electrocatalysis.

Graphical abstract: Iridium nanohollows with porous walls for acidic water splitting

Supplementary files

Article information

Article type
Paper
Submitted
21 mar 2022
Accepted
08 iyl 2022
First published
11 iyl 2022

J. Mater. Chem. A, 2022,10, 20005-20010

Iridium nanohollows with porous walls for acidic water splitting

X. Bao, S. Li, C. Hao, Y. Qin, Y. Gong, Y. Yang, A. Xu and M. Luo, J. Mater. Chem. A, 2022, 10, 20005 DOI: 10.1039/D2TA02193E

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