Direct Synthesis of Dual Mo-Based Functional Materials Derived from Molybdenite by Molten Salt Paired Electrolysis

Abstract

A facile synthesis process that facilitates the industrial-scale production of catalysts is the prerequisite of the hydrogen evolution reaction (HER) industry. Molybdenum-based catalysts are ideal alternatives for precious-metal-based HER materials; however, they remain challenging in scale-up preparation due to the costly and complex Mo sources. Herein, we propose a molten salt paired electrolysis approach to synthesize transition-metal-doped Mo₂C catalysts directly from molybdenite (mainly consisting of micrometer-scale MoS₂ bulks), an earth-abundant natural Mo ore. Unlike Fe-doped Mo₂C in which those transition metal dopants are inclined to diffuse into inner planes of Mo₂C, this unique synthesis approach leverages the differences in transition metal diffusion energy barriers, ultimately leading to the development of Ni-doped Mo₂C catalytic materials with specific Ni-enriched interfaces. Owing to the unique design and structures of the catalyst, the interfacially Ni-enriched Ni-doped Mo₂C exhibited promising HER performance and long-term stability. Very interestingly, MoS₂ nanoflakes, as side products, can be collected at the anode side while interfacially Ni-enriched Mo₂C was concurrently obtained at the cathode side during the electrolytic synthesis process. This work not only deepens our knowledge on constructing active-site-enriched interfaces that are beneficial to HER but also gives clues to upcycling raw materials.