From an Fe2P3 complex to FeP nanoparticles as efficient electrocatalysts for water-splitting† †Electronic supplementary information (ESI) available: Instrumental details, experimental procedures, detailed characterization of the molecular precursor as well as the material, electrochemical catalytic activities. CCDC 1588191 and 1588192. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8sc03407a

The first β-diketiminato triphosphido diiron complex was synthesized as a versatile molecular single-source precursor for the production of functional FeP that acts as a powerful and durable bifunctional electrocatalyst for water splitting.
In large-scale, hydrogen production from water-splitting represents the most promising solution for a clean, recyclable, and low-cost energy source. The realization of viable technological solutions requires suitable efficient electrochemical catalysts with low overpotentials and long-term stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) based on cheap and nontoxic materials. Herein, we present a unique molecular approach to monodispersed, ultra-small, and superiorly active iron phosphide (FeP) electrocatalysts for bifunctional OER, HER, and overall water-splitting. They result from transformation of a molecular iron phosphide precursor, containing a [Fe2P3] core with mixed-valence FeIIFeIII sites bridged by an asymmetric cyclo-P(2+1)3– ligand. The as-synthesized FeP nanoparticles act as long-lasting electrocatalysts for OER and HER with low overpotential and high current densities that render them one of the best-performing electrocatalysts hitherto known. The fabricated alkaline electrolyzer delivered low cell voltage with durability over weeks, representing an attractive catalyst for large-scale water-splitting technologies.