Synergistic engineering of Ag doping and P vacancies in nanoflower-like Ni2P for acrylamide-assisted electrolysis of seawater splitting

Given the vast abundance of seawater resources on Earth, direct electrolysis of seawater as an attractive approach for hydrogen fuel production. Seawater electrolysis coupled with the acrylamide (AA) oxidation replacing oxygen evolution is an effective way for simultaneously treating AA wastewater and producing H2. Herein, we propose Ag-doped nanoflower-like Ni2P on Ni foam (Ag-Ni2P NF) and generate P vacancies by treatment with NaBH4 solution (Ag/B-Ni2P NF) to serve as a bifunctional catalyst. The Ag/B-Ni2P NF can replace oxygen evolution reaction (OER) with AA oxidation reaction (AOR) in anode (235 mV to drive 100 mA cm−2) and hydrogen evolution reaction (HER) in cathode (295 mV to drive 100 mA cm−2). The density functional theory (DFT) calculations and experimental results collectively elucidate the factors contributing to the enhanced catalyst activity. Due to its nanoflower-like structure, robust Ni−B bond interaction, P vacancies, large surface area and strong electrocatalytic activity, the Ag/B-Ni2P NF exhibited high stability and reusability in seawater. DFT calculations reveal that Ag atoms facilitate strong metal-support interactions, while P vacancies create adsorption sites for B integration. The potential for AOR in seawater can be minimized to 1.91 V, generating a current density of 100 mA cm−2 using Ag/B-Ni2P NF in a two-electrode system. As a result, AA oxidation and H2 production in a single system can efficiently reduce energy consumption while promoting environmental protection in seawater resources.