Iron adsorption engineering facilitated by Cu doping on cobalt hydroxide host with enhanced oxygen evolution reaction

Iron plays a crucial role in improving the oxygen evolution reaction (OER) activity of hydroxide materials. Increasing the number of iron active sites at the solid-liquid interface is beneficial to enhancing the OER performance of catalysts but still challenging. Here, by systematic exploring the activity trends of M(OH)(x), and Cu-M(OH)(x) (M = Mn, Cu, Ni, Fe, and Co), we discover that the Cu doping can promote the deposition of Fe active sites on metal hydroxide and Cu-Co(OH)(2) shows the most favorable iron adsorption capacity. When loaded on a conductive substrate (cobalt foam (OF), the M-Cu-Co(OH)(2)/CF (Co(OH)(2) prepared by molten salt method) exhibits an attractive low overpotential of 337 mV at 1,000 mA-cm(-2). Using in anion exchange membrane (AEM) water electrolyzer, the single cell with M-Cu-Co (OH)(2)/CF as anode catalyst performs a stable cell voltage of 2.02 V to reach 1,000 mA.cm(2) over 24 h, indicating a great application potential for actual electrolytic water. Therefore, the promoted adsorption of copper on iron provides a new perspective for further enhancing the OER activity of other metal hydroxides.