Engineering Water-Lotus-like Iridium-Cobalt Carbonate Hydroxides on Plasma-Treated Carbon Fibers for Enhanced Electrocatalytic Oxygen Evolution.

The sluggish kinetics of the oxygen evolution reaction (OER) in alkaline water electrolysis remains a significant challenge for developing high-efficiency electrocatalytic systems. In this study, we present a three-dimensional, micrometer-sized iridium oxide (IrO 2 ) - decorated cobalt carbonate hydroxide (IrO 2 -P-CoCH) electrocatalyst, which is engineered in situ on a carbon cloth (CC) substrate pretreated with atmospheric-pressure dielectric barrier discharge (DBD) plasma (PCC). The electrocatalyst features petal-like structures composed of nanosized rods, providing abundant reactive areas and sites, including the oxygen vacancy caused by the air-DBD plasma. As a result, the IrO 2 -P-CoCH/PCC electrocatalyst demonstrates an outstanding OER performance, with overpotentials of only 190 and 300 mV required to achieve current densities of 10 mA cm -2 ( j 10 ) and 300 mA cm -2 ( j 300 ), respectively, along with a low Tafel slope of 48.1 mV dec -1 in 1.0 M KOH. Remarkably, benefiting from rich active sites exposed on the IrO 2 -P-CoCH (Ir) heterostructure, the synergistic effect between IrO 2 and CoCH enhances the charge delivery rates, and the IrO 2 -P-CoCH/PCC exhibits a superior electrocatalytic activity at a high current density (300 mV/ j 300 ) compared to the commercial benchmarked RuO 2 /PCC (470 mV /j 300 ). Furthermore, the IrO 2 -P-CoCH/PCC electrocatalyst shows exceptional OER stability, with a mere 1.3% decrease with a current density of j 10 for 100 h testing, surpassing most OER catalysts based on CC substrates. This work introduces a novel approach for designing high-performance OER electrocatalysts on flexible electrode substrates.