Cobalt oxide-supported iridium oxide nanoparticles with strong metal oxide-support interaction for efficient acidic oxygen evolution reaction.

Abstract

Understanding and regulating the deprotonation process in an acidic oxygen evolution reaction (OER) is highly desirable for a proton exchange membrane water electrolyzer (PEMWE). Herein, ultrasmall IrO₂ nanoparticles were firmly anchored on an acid-resistant Co₃O₄ support (IrO₂/Co₃O₄) through galvanic replacement, with strong metal oxide-support interaction (SMOSI) induced and responsible for the accelerated deprotonation process during OER. For IrO₂/Co₃O₄, a low overpotential of 256 mV at 10 mA cm^-2 could be achieved for an acidic OER, with sustained operation exceeding 1000 h. More importantly, a PEMWE assembled with IrO₂/Co₃O₄ as the anode could survive 120 h and 40 h of operation at industrial-level current densities of 0.5 and 1 A cm^-2, with cell voltages of 1.64 and 1.77 V, respectively. Experimental results and theoretical calculations together demonstrate that the SMOSI induced by the lattice-mismatched interfaces in IrO₂/Co₃O₄ could increase the p-band center of O_bri (bridging oxygen) sites in the Ir-O_bri bonds. Such an enhanced p-band center would strengthen the proton acceptance of O_bri sites, facilitating the deprotonation process, and thus improving OER activity and stability. This work presents an alternative approach for the regulation of the deprotonation process via SMOSI and the design of an inexpensive and efficient electrocatalyst towards an industrial-level PEMWE.