Modular Design of Noble-Metal-Free Mixed Metal Oxide Electrocatalysts for Complete Water Splitting

Electrocatalytic water splitting into H-2 and O-2 is a key technology for carbon-neutral energy. Here, we report a modular materials design leading to noble metal-free composite electrocatalysts, which combine high electrical conductivity, high OER and HER reactivity and high durability. The scalable bottom-up fabrication allows the stable deposition of mixed metal oxide nanostructures with different functionalities on copper foam electrodes. The composite catalyst shows sustained OER and HER activity in 0.1M aqueous KOH over prolonged periods (t > 10 h) at low overpotentials (OER: approximate to 300 mV; HER: approximate to 100 mV) and high faradaic efficiencies (OER: approximate to 100%, HER: approximate to 98%). The new synthetic concept will enable the development of multifunctional, mixed metal oxide composites as high-performance electrocatalysts for challenging energy conversion and storage reactions.