Incorporating ultra-small N-doped Mo2C nanoparticles onto 3D N-doped flower-like carbon nanospheres for robust electrocatalytic hydrogen evolution

Abstract

Developing highly-efficient and stable hydrogen evolution reaction (HER) electrocatalysts plays a crucial role in realizing the hydrogen production from electrocatalytic water splitting. Herein, ultra-small and nitrogen-doped molybdenum carbide (N-Mo 2 C) nanoparticles with oxidized surfaces are facilely synthesized with the assistance of cationic surfactants and simultaneously anchored onto three-dimensional nitrogen-doped flower-like carbon nanospheres (NFCNS), and the N-Mo 2 C/NFCNS composites are further investigated as HER electrocatalysts. Analysis results reveal that nitrogen atoms are doped into both the lattice and the carbon framework of Mo 2 C, resulting in low desorption energy of Mo-H bond for the easy evolution of hydrogen gas. Moreover, the high specific area of NFCNS enables enrichment of N-Mo 2 C nanoparticles, and its open framework facilitates fast ion diffusion. As a result, the N-Mo 2 C/NFCNS composites exhibit impressive HER activities with low overpotential, small Tafel slope, and excellent durability in both acidic and alkaline media, which outperform most of the reported Mo-based HER catalysts and are also highly comparable to the commercial Pt/C catalyst. Not limited to HER electrocatalysts, this work should open a new avenue for tailoring highly-efficient carbon/metal compounds-based electrocatalysts for oxygen reduction reaction, oxygen evolution reaction, nitrogen reduction reaction, etc. A simple strategy to downsize and stabilize Mo 2 C nanoparticles within 3D N-doped flower-like carbon nanospheres has been developed by using cationic surfactant as linker between carbon and molybdenum sources. The nitrogen doping in Mo 2 C leads to superior hydrogen evolution activities and excellent durability in both acidic and alkaline media, which outperform most of the current Mo-based electrocatalysts. • A simple protocol is introduced to downsize and stabilize molybdenum carbide electrocatalysts. • Nitrogen-doped molybdenum carbide electrocatalysts are developed for hydrogen evolution. • Three-dimensional nitrogen-doped flower-like carbon nanospheres are designed as supports. • Lowering Mo-H desorption energy owing to nitrogen doping facilitates hydrogen evolution.