A self-supported 3D porous high entropy alloy with progressive formation of needle-shaped nanowires during reactions for maintained excellent electrocatalytic oxygen evolution

Abstract

An efficient 3D porous bulk electrocatalyst is a feasible way to improve the conductivity. Herein, the preparation of a novel self-supporting 3D porous bulk FeCoNiMgB catalyst exhibits excellent electrocatalytic activity and stability properties towards OER. The self-supporting 3D porous framework structure catalyst possesses multiple advantages including large surface area, excellent conductivity, leading to the fast mass and charge transfers, low electrochemical impedance and fast water splitting reaction kinetics. As a result, the 3D porous bulk FeCoNiMgB catalyst requires substantially lower overpotential (234 mV) with a small Tafel slope (36.1 mV dec−1) as compared to pure FeCoNiMgB powders and RuO2 electrodes, as well as stable catalytic properties for over 72 h with no obvious evidence of degradation. Comparative structural characterization and DFT calculations reveal that the needle-shaped nanowires with Fe rich are formed from many open pores during the OER process, which helps to reduce the rate determining step energy barrier (O∗→OOH∗) for OER, and thus has excellent long-term electrochemical stability for continuous oxygen production under alkaline conditions. This work provides a new feasible and promising protocol to realize a novel self-supporting 3D porous bulk high entropy alloy catalyst as an inexpensive catalyst for efficient water splitting.