Polymetallic phosphides evolved from MOF and LDH dual-precursors for robust oxygen evolution reaction in alkaline and seawater media

Abstract

Water electrolysis is an efficient, clean and sustainable method for hydrogen production. However, high cost performance oxygen evolution reaction (OER) catalysts become the key to realize the industry-scale hydrogen production from water electrolysis. Herein, we for the first time report a polymetallic transition metal phosphide (Fe2P–NiCoP) catalyst derived from iron-containing metal-organic frameworks (MIL-88A) and NiCo-LDH as double precursors, effectively driving the OER in alkaline media. Experimental and density functional theory (DFT) calculation results verify that, the NiOOH/FeOOH, as real active site for OER generated by Fe2P–NiCoP reconstruction, reduces the adsorption energy of oxygen-containing intermediates and accelerate the reaction kinetics. As expected, only 239 and 260 mV overpotentials are required to reach current densities of 20 and 50 mA cm−2 in 1 M KOH solutions, which is far better than commercial RuO2 toward OER. Besides, Fe2P–NiCoP also achieves long-term stability up to 100 h, providing the possibility of commercial large-scale applications. Furthermore, it still obtains the outstanding activity in direct electrolysis of alkaline seawater, with only 258 and 278 mV overpotentials needed to reach current densities of 20 and 50 mA cm−2, respectively. Undoubtedly, Fe2P–NiCoP is one of the most promising non-noble metal electrocatalysts for practical hydrogen production from water splitting.