NaCl-Assisted Ultrasmall Mo₂C Nanocrystals Confined in N, S Double-Doped Hierarchical Porous Carbon for Efficient Hydrogen Generation

Abstract

Refining the size of nonprecious metal-based catalysts and restricting them in multiheteroatom-doped hierarchical porous carbon can achieve efficient electrical energy conversion. In this study, ultrasmall Mo2C nanocrystals with an average size of 4.9 nm are fitted to N and S double-doped hierarchical porous carbon (us-Mo2C/N,S-HPC) through a template strategy and used for efficient hydrogen production. First, the metal molybdenum salt is captured and fixed by natural bamboo leaf fibers which are pulverized by a ball mill. Meanwhile, the soluble sodium salt is largely filled in the bamboo leaf tissue. Subsequently, Mo2C nanocrystals formed by high-temperature reduction are uniformly anchored on the bamboo-derived N, S double-doped hierarchical porous carbon. As a result, the prepared us-Mo2C/N,S-HPC requires 150, 197, and 148 mV overpotential to drive a current density of 10 mA cm–1 at pH = 0, 7, and 14, respectively. This improvement is attributed to the synergistic effects of size controllable Mo 2 C, multidoped heteroatoms, and multiscale assembly structures. Significantly, this study is conducive to the construction of ultrafine nanocrystals and the high-value conversion of waste biomass.