Multifunctional Amorphous Co Phosphosulfide-Coated Fe-Co Carbonate Hydroxide for Highly Efficient Overall Water Splitting

Abstract

Non-noble metal electrocatalysts current represent an appealing alternative to noble metal electrocatalysts for water oxidation reaction in alkaline conditions. However, the poor water reduction reaction activities limit their performance in driving overall water splitting in alkaline electrolytes. Here, we report the preparation of bifunctional amorphous Co phosphosulfide-doped Fe-Co carbonate hydroxide on the surface of Ni foam (Co-S-P/Fe1Co1COH/NF) through hydrothermal and electrochemical techniques. The efficient full water oxidation and reduction properties of the Co-S-P/Fe1Co1COH/NF were verified in pH = 14 medium. The results proved that a phosphorus and sulfur co-depositing catalyst could exhibit excellent anodic oxidation and cathodic reduction activity for full water splitting. Furthermore, the optimal electrocatalyst can afford a current density of 10 mA cm−2 at an overpotential of only 73 mV for hydrogen evolution from water reduction and 50 mA cm−2 at 160 mV for oxygen evolution from water oxidation in 1.0 M KOH solution, showing better activities than most non-noble metal materials. The improved electrocatalytic activities could be attributed to the increased number of active sites and the synergetic cooperation in the prepared material. Additionally, the Co-S-P/Fe1Co1COH/NF catalyst as both cathode and anode only needs a voltage of 1.5 V to achieve 10 mA cm−2 in 1 M KOH solution for full water splitting, which lays a good foundation for full water splitting in practical applications.