Facile Access to Active g - NiOOH Electrocatalyst for Durable Water Oxidation Derived From an Intermetallic Nickel Germanide Precursor.

Identifying novel classes of precatalysts for the oxygen evolution reaction (OER by water oxidation) with enhanced catalytic activity and stability is a part of key strategies to enable chemical energy conversion. The vast chemical space of intermetallic phases offers plenty of opportunities to discover OER electrocatalysts with improved performance. Here we report intermetallic nickel germanide (NiGe) acting as a superiorly active and durable Ni-based electro(pre)catalysts for OER  produced from  a molecular  bis(germylene )- Ni precursor.  The ultra-small NiGe nanocrystals deposited on both nickel foam and fluorinated tin oxide (FTO) electrodes show lower overpotentials and a durability of over three weeks (505 h) in comparison to the state-of-the-art Ni-, Co-, Fe-, and benchmark NiFe-based electrocatalysts under identical alkaline OER conditions. In contrast to other Ni-based intermetallic precatalysts under alkaline OER conditions, an unexpected electroconversion of NiGe into  g -Ni III OOH with intercalated  OH - /CO 3 2-   transpired that served as a highly active structure as shown by various ex-situ methods and quasi in-situ Raman spectroscopy .