Metal-organic framework derived spinel tricobalt tetroxide with trifle iridium sites for near-pH-neutral seawater electrolysis

Abstract

Metal-organic frameworks (MOFs) derived spinel tricobalt tetroxide (Co3O4) electrocatalysts incorporated with trifle Iridium (Ir) sites are in-situ grown on nickel foam (NF) substrate (Ir-Co3O4/NF) as effective anode for OER especially in near-pH-neutral seawater with high ability to suppress chlorine evolution reaction. Density functional theory (DFT) calculations indicate that the trifle Ir sites can be safeguarded in spinel Co3O4via structural-confinement and charge-redistribution so that the Ir and Co sites with their bridged electrophilic O ligands can serve as the active sites for boosting OER performance. As expected, a relatively low OER overpotential of 370 mV @ 10 mA cm−2 and it is achieved with at least 7 days durability under the current density of 100 mA cm−2 in near-pH-neutral simulated seawater with high selectivity toward OER. In same condition, a fabricated electrolyzer using it presents excellent electrocatalytic performance with a cell voltage of 2.11 V @ 100 mA cm−2, strongly suggesting that the present electrolyzer has great promising for practical seawater electrolysis.