Sulfur-bridged iron-polyphthalocyanine on CuxO/copper foam: efficient and durable electrocatalyst for overall water splitting

Overall water splitting is a promising route to produce green hydrogen in a sustainable manner. However, its practical large-scale use critically requires efficient, sustainable and easy-to-operate catalysts that can drive both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in the same electrolyte. In this report, we present a facile synthesis of one such electrocatalyst that is composed of amorphous sulfur-bridged iron polyphthalocyanine (FeSPPc) grown in situ on CuxO-coated Cu foam. The material is denoted as FeSPPc/CuxO/CF, where x indicates the non-stoichiometric hybrid valence states of Cu, including its +1 and +2 oxidation states. The as-generated material has unique catalytic sites, large electrochemically active surface area, and high electrical conductivity. It electrocatalyzes the HER in N-2-saturated KOH electrolyte (1 M) with a current density of 10 mA cm(-2) at an overpotential of only 38 mV. It also electrocatalyzes the OER in O-2-saturated KOH solution (1 M) with 10 mA cm(-2) at an overpotential of 350 mV. The material is stable while catalyzing both reactions as well. Importantly, a water electrolyzer assembled using FeSPPc/CuxO/CF as both cathode and anode electrodes in the same alkaline electrolyte requires only 1.48 V to drive the reaction with 10 mA cm(-2) while remaining stable.

Automated summary

The synthesis of a highly efficient, stable, and easy-to-operate catalyst capable of simultaneously driving the hydrogen evolution and oxygen evolution reactions has been achieved in this study. The FeSPPc/CuxO/CF material exhibits high activity and stability in electrocatalyzing both HER and OER processes, with low overpotentials and high electrical conductivity, making it a promising candidate for water electrolysis.