Molten Electrolyte-Modulated Electrosynthesis of Multi-Anion Mo-Based Lamellar Nanohybrids Derived from Natural Minerals for Boosting Hydrogen Evolution.

Abstract

The multi-anion molybdenum-based nanohybrids, N-doped β-Mo2C/MoP/MoOx (denoted as MoCPO), serving as a highly efficient catalyst for hydrogen evolution reaction (HER), are fabricated via a simple and scalable electrosynthesis in molten NaCl-KCl, which integrates pyrolysis/electroreduction/compounding into a one-pot strategy using polyphosphazenes (PPAs) and earth-abundant molybdenite (mainly MoS2) as precursors. The deliberately selected PPA and molten electrolyte ensure the unique lamellar nanostructures and the blending of multiple anions of C, N, P, and O in the obtained catalyst, specifically, triggering the in situ formation of the structural oxygen vacancies (VO) in MoCPO. The nature of the hybrids can be regulated by adjusting the synthesis condition. The optimized hybrid displays a low overpotential of 99.2 mV at 10 mA cm-2 for HER in 0.5 M H2SO4 and stays active over a broad pH range. The theoretical calculations reveal that VO in the hybrids serves as favorable active sites, thus contributing to the superior HER activity. Moreover, MoCPO is also effective for overall water splitting as a bifunctional catalyst.