In situ electrochemical synthesis of superhydrophilic NiCoMn trimetallic-alloy nanosheets via the dynamic hydrogen bubble template method for developing high current density hydrogen production electrocatalysts

Abstract

This article discusses the use of the dynamic hydrogen bubble template (DHBT) technique for in situ electrodeposition and simultaneous formation of NiCoMn trimetallic alloy nanosheets on nickel foam (NF). Compared to Ni/NF metallic and NiCo/NF, NiMn/NF, and CoMn/NF bimetallic electrodes, the NiCoMn/NF trimetallic alloy electrocatalyst exhibited favorable activity and durability. It provides current densities of −10, −100, −500, and −1000 mA cm⁻² at overpotentials of −33, −131, −168, and −242 mV, respectively, and shows a Tafel slope of 44.2 mV dec⁻¹. Additionally, the NiCoMn/NF electrode can maintain its stability without significant degradation in the morphology, while delivering a high current density for the HER (−500 mA cm⁻² at 150 h). Utilizing a NiCoMn/NF‖NiCoMn/NF pair in a water splitting setup achieved an activation potential of 1.43 V at 10 mA cm⁻² current density. Furthermore, the NiCoMn/NF‖NiCoMn/NF couple can withstand a 300 h chronopotentiometry test to provide a current density of 100 mA cm⁻² with high durability. In situ and simultaneous synthesis with a fast, simple, and low-cost technique, the special morphology, the high synergy between Ni, Co, and Mn elements, and the superhydrophobic properties and extensive electrochemically active surface area with an ability to provide high current density are key advantages of the NiCoMn/NF electrocatalyst. Our quantum chemical calculations using density functional theory (DFT) revealed the synergistic role of Co and Mn in enhancing the efficiency of water splitting. Specifically, Co atoms significantly increase the conductivity, while Mn atoms, identified as the most reactive sites, primarily drive the HER, followed by Co and then Ni. This synergy between Co and Mn is crucial for optimizing catalytic performance in water splitting. These features add to the importance of its industrial usage for the sustainable development of hydrogen energy.