Mn-doped nickel-copper phosphides as oxygen evolution reaction electrocatalyst in alkaline seawater solution

Abstract

Compared with traditional water electrolysis, electrolysis of seawater has larger resources and a brighter future. However, seawater contains more elements that have greater corrosive effects on electrodes; especially chloride ions (seawater contains more chloride ions) have the greatest impact. The existence of the corrosion problem creates greater difficulties in electrolyzing seawater, further limiting the efficiency of the electrocatalyst for electrolysis of seawater. In this paper, we report a Mn-doped Ni2P/Cu3P as an environmentally friendly monofunctional electrode for seawater electrolysis, which was made by a simple hydrothermal phosphatization operation method. The experimental results show that Mn-doped Ni2P/Cu3P presents overpotential of only 161 mV for oxygen evolution reaction (OER) at iR compensation of 90 and a current density of 10 mA cm−2. It has a small Tafel slope (25.15 mV dec−1) and a large capacitance (9.58 mF cm−2 on 1 × 1 nickel foam), which exceeds most reported oxygen evolution activities of non-precious metal-based electrocatalysts for electrolysis of alkaline seawater. The performance of Ni2P/Cu3P was probably significantly enhanced due to Mn doping by some characterization means. Through Density functional theory (DFT) analysis, it is known that the doping of Mn gives a large enhancement in the adsorption energy of water when Ni2P/Cu3P is electrolyzed with seawater. This paper provides train of thought for the exploration of excellent electrocatalysts for electrolysis of alkaline seawater.