Unprecedented high oxygen evolution activity of electrocatalysts derived from surface-mounted metal-organic frameworks.

The oxygen evolution reaction (OER) is a key process for renewa-ble energy storage. However, developing non-noble metal OER electrocatalysts with high activity, long durability and scalability remains a major challenge. Herein, high OER activity and stability in alkaline solution were discovered for mixed nickel/cobalt hy-droxide electrocatalysts, which were derived in one-step procedure from oriented surface-mounted metal-organic framework (SURMOF) thin films that had been directly grown layer-by-layer on macro- and microelectrode substrates. The obtained mass activi-ty of ~2.5 mA∙μg-1 at the defined overpotential of 300 mV is one order of magnitude higher than that of the benchmarked IrO2 elec-trocatalyst and at least 3.5 times higher than the mass activity of any state-of-the-art NiFe-, FeCoW- or NiCo-based electrocatalysts reported in the literature. The excellent morphology of the SURMOF-derived ultrathin electrocatalyst coating led to a high exposure of the most active Ni- and Co-based sites.