Fabrication of 3D microporous amorphous metallic phosphides for high-efficiency hydrogen evolution reaction

Abstract

The design and prediction of composition and structure is critical for the development of robust and efficient oxygen evolution reaction (OER) catalysts for water splitting. To enhance electrochemical catalytic activity of catalyst, a series of 3D microporous amorphous metallic phosphides, such as NiP, FeP, CoP, NiFeP, FeCoP, NiCoP and NiFeCoP, were electrodeposited on nickel mesh (dubbed NM) via hydrogen bubbles electroplating technique. The electrocatalytic performances of all as-prepared phosphides in alkaline solution for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were investigated. The optimal 3D microporous NiFeCoP/NM electrode exhibits remarkable catalytic activity for HER and delivers a current density of 10 mA cm−2 only required an extremely low overpotential (33 mV) and a small Tafel slope (71.1 mV dec−1) in 1.0 M KOH solution. Meanwhile the NiFeCoP/NM electrode also shows outstanding strong durability and robustness in alkaline water electrolysis. Further, the NiFeCoP/NM electrode displays superior catalytic activity towards OER. In a two-electrode water electrolytic cell, the bi-functional NiFeCoP/NM electrodes could obtain current densities of 10 and 50 mA cm−2 at overall cell potentials of only 1.64 and 1.82 V, respectively. The remarkable electrocatalytic activities of the NiFeCoP/NM electrode both for HER and OER are attributed to the synergistic effect of tri-metal elements in metallic phosphide, amorphous phase structure, and the superlarge electrochemical surface area fabricated by the hydrogen bubbles electroplating.