A bifunctional electrocatalyst for alkaline seawater splitting using ruthenium doped nickel molybdenum phosphide nanosheets

Abstract

Electrolysis of sea water is regarded as the most appealing and promising approach for the generation of hydrogen green energy, and even it lowers the cost of hydrogen production. However, for seawater electrolysis, highly efficient and robust electrocatalysts that can withstand chloride corrosion on the electrodes, particularly the anode, are required. Here, we present the synthesis of nickel molybdenum phosphide engineered with ruthenium supported on nickel foam (Ru₂₂NiMoP₂/NF) by a hydrothermal technique followed by reactions under autogenic pressure at elevated temperatures (RAPET) in a Swagelok, which demonstrated excellent electrocatalytic activity in alkaline sea water. For the hydrogen evolution reaction (HER), Ru₂₂NiMoP₂/NF requires low overpotentials of 60 and 52 mV to achieve a current density of 10 mA cm⁻² compared to commercial Pt/C/NF (65 & 130 mV) in alkaline and alkaline sea water, respectively. Similarly, in the case of the oxygen evolution reaction (OER), lower overpotentials of 250 and 240 mV are required to reach a current density of 10 mA cm⁻² for Ru₂₂NiMoP₂/NF in alkaline and alkaline sea water. Because of the strong interaction between Ru₂₂NiMoP₂ and NF, and the corrosion resistive nature, Ru₂₂NiMoP₂ demonstrated excellent alkaline sea water splitting at a voltage of 1.53 V which is less than or close to the alkaline water splitting (1.54 V@10 mA cm⁻²) and it has shown excellent durability for approximately 10 h. Therefore, the results depicted above may provide significant advances in the design of high-performance and tough electrocatalysts for pure sea water splitting with a high current density.