A Low‐Temperature Molecular Precursor Approach to Copper‐Based Nano‐Sized Digenite Mineral for Efficient Electrocatalytic Oxygen Evolution Reaction

In the urge of designing noble metal‐free and sustainable electrocatalysts for oxygen evolution reaction (OER), herein, a mineral Digenite Cu(9)S(5) has been prepared from a molecular copper(I) precursor, [{(PyHS)(2)Cu(I)(PyHS)}(2)](OTf)(2) (1), and utilized as an anode material in electrocatalytic OER for the first time. A hot injection of 1 yielded a pure phase and highly crystalline Cu(9)S(5), which was then electrophoretically deposited (EPD) on a highly conducting nickel foam (NF) substrate. When assessed as an electrode for OER, the Cu(9)S(5)/NF displayed an overpotential of merely 298±3 mV at a current density of 10 mA cm(−2) in alkaline media. The overpotential recorded here supersedes the value obtained for the best reported Cu‐based as well as the benchmark precious‐metal‐based RuO(2) and IrO(2) electrocatalysts. In addition, the choronoamperometric OER indicated the superior stability of Cu(9)S(5)/NF, rendering its suitability as the sustainable anode material for practical feasibility. The excellent catalytic activity of Cu(9)S(5) can be attributed to the formation of a crystalline CuO overlayer on the conductive Cu(9)S(5) that behaves as active species to facilitate OER. This study delivers a distinct molecular precursor approach to produce highly active copper‐based catalysts that could be used as an efficient and durable OER electro(pre)catalysts relying on non‐precious metals.