NiMoO₄/Ni Heterostructure Supported on B-Doped Carbon Nanotubes as a Robust Electrocatalyst for Efficient Alkaline Water/Seawater Hydrogen Evolution Reaction

Electrocatalytic water splitting is a promising green technology for hydrogen production, but its industrial application faces two major challenges: slow kinetics of the hydrogen evolution reaction (HER) and insufficient catalyst durability. These limitations are particularly evident in corrosive seawater environments, where accelerated catalyst deactivation severely hampers practical applications. In this paper, a B-doped carbon nanotube-supported NiMoO4/Ni heterostructure catalyst (NiMoO4/Ni/B-CNTs) is synthesized via a hydrothermal-calcination method. The NiMoO4/Ni/B-CNTs catalyst exhibits outstanding HER activity, showing overpotentials of 42 mV (1 M KOH) and 48 mV (alkaline seawater) at 10 mA cm–2, respectively, comparable to that of noble metal Pt/C, indicating notable superiority in the HER field. Remarkably, the NiMoO4/Ni/B-CNTs remain stable after 10,000 cycles of cyclic voltammetry (CV) and 200 h of continuous operation in alkaline freshwater and alkaline seawater environments, with 95% current density retention, demonstrating their potential for hydrogen production on an industrial scale. The superior HER performance of NiMoO4/Ni/B-CNTs is attributed to the interfacial effect between NiMoO4 and Ni, and the synergistic effect between the B-CNTs supports and NiMoO4/Ni, which collectively facilitates the HER process. This study opens a potential path for the development of nonprecious metal efficient HER electrocatalysts for alkaline freshwater/seawater electrolysis.