Cobalt vacancy-originated TiMnCoCN compounds with a self-adjusting ability for the high-efficiency acidic oxygen evolution reaction

Abstract

Oxygen evolution reaction (OER) electrocatalysts in acidic media, except for precious IrO₂, have difficulty realizing good electrocatalytic activity and high electrochemical stability simultaneously. However, the scarcity of IrO₂ as an acidic OER electrocatalyst impedes its large-scale application in hydrogen generation, organic synthesis, nonferrous metal production and sewage disposal. Herein, we report the design and fabrication of a nanoporous TiMnCoCN compound based on the nanoscale Kirkendall effect, possessing an intriguing self-adjusting capability for the oxygen evolution reaction (OER) in a 0.5 M H₂SO₄ solution. The nanoporous TiMnCoCN compound electrode for the acidic OER displays a low overpotential of 143 mV for 10 mA cm^-2 and exhibits no increase in potential over 50,000 s, which is ascribed to the self-adjusting ability, Carbon/nitrogen (C/N) incorporation and nanoporous architecture. The concentration of inert TiO₂ on the reconstructed surface of the compound can self-adjust with the change in OER potential via a cobalt-dissolved vacancy approach according to the stabilization requirement. In this work, the self-reconstruction law of surface structure was discovered, providing a novel strategy for designing and fabricating nonnoble OER electrocatalysts with superior catalytic performance and robust stability in acidic media.

Keywords: Acidic medium; Nanoscale Kirkendall effect; Nonnoble catalyst; Oxygen evolution reaction; Self-adjusting surface reconstruction.