Melamine-assisted synthesis of ultrafine Mo2C/Mo2N@N-doped carbon nanofibers for enhanced alkaline hydrogen evolution reaction activity

Abstract

Noble metal-free electrocatalysts with high activity are highly desirable for the large-scale application of hydrogen evolution reaction (HER). Mo 2 C-based nanomaterials have been proved as a promising alternative to noble metal-based electrocatalysts owing to the Pt-resembled d-band density and optimal intermediates-adsorption properties. However, the aggregation and excessive growth of crystals often occur during their high-temperature synthesis procedure, leading to low catalytic utilization. In this study, the ultrafine Mo 2 C/Mo 2 N heterostructure with large surface and interface confined in the N-doped carbon nanofibers (N-CNFs) was obtained by a melamine-assisted method. The synergistic effect of Mo 2 C/Mo 2 N heterostructure and plenty active sites exposed on the surface of ultrafine nanocrystals improves the electrocatalytic activity. Meanwhile, the N-CNFs ensure fast charge transfer and high structural stability during reactions. Moreover, the in-situ synthesis method strengthens the interfacial coupling interactions between Mo 2 C/Mo 2 N heterostructure and N-CNFs, further enhancing the electronic conductivity and electrocatalytic activity. Owing to these advantages, Mo 2 C/Mo 2 N@N-CNFs exhibit excellent HER performance with a low overpotential of 75 mV at a current density of 10 mV cm −2 in alkaline solution, superior to the single-phased Mo 2 C counterpart and recently reported Mo 2 C/ Mo 2 N-based catalysts. This study highlights a new effective strategy to design efficient electrocatalysts via integrating heterostructure, nanostructure and carbon modification.

In Situ Growth of Mo2C Crystals Stimulating Sodium-Ion Storage Properties of MoO2 Particles on N-Doped Carbon Nanobundles

“…The N 1s spectrum (Figure i) presents binding energies at 399.8, 398.6, 396.9, and 395.4 eV, which correspond to graphitic-N, pyrrolic-N, pyridinic-N, and Mo–N bonds, respectively. The presence of Mo–N bonds implies that the MoO 2 and Mo 2 C components have strong coupling effects with nitrogen atoms of N-CNBs, which contributes to improving the charge transport ability and reinforcing the structural stability of the composite. , In contrast, MoO 2 /C (Figure S9) also shows the N-doping in carbon and the strong coupling effects (Mo–N bond), as well as confirming the formation of the MoO 2 component. These results suggest that the structural advantages of N-doping and coupling are expected to improve the sodium-ion storage properties of MoO 2 @Mo 2 C/C.…”

Graphite Nanoflake-Modified Mo2C with Ameliorated Interfacial Interaction as an Electrocatalyst for Hydrogen Evolution Reaction

“…As depicted in Figure a,b, Mo 2 C/G-B exhibits polarization curves with an ultralow overpotential of 136 mV at a current density of 10 mA cm –2 (η 10 ), revealing higher HER performance than Mo 2 C/G-A (255 mV) and Mo 2 C/G-C (183 mV). Furthermore, the corresponding Tafel plot in Figure c is given to explore the HER kinetics, and the resulting Tafel slope of Mo 2 C/G-B is 76.81 mV dec –1 , while Pt/C, Mo 2 C/G-A, and Mo 2 C/G-C show a Tafel slope of 31.26, 94.55 mV, and 81.64 dec –1 , respectively, implying the Volmer–Heyrovsky reaction mechanism in different degree. ,− The electrochemical performance of Mo 2 C/G-B also stands out compared to that of other Mo 2 C-based electrode materials for electrocatalytic water splitting in alkaline solution (Table ), especially the ultralow overpotential with less electrode loading mass.…”

In situconstruction of an α-MoC/g-C3N4Mott–Schottky heterojunction with high-speed electron transfer channel for efficient photocatalytic H2evolution

“…Molybdenum carbide has the merits of a Pt-like electronic structure, good electrical conductivity, and excellent thermal and chemical stability, enabling it to be widely applied in the fields of thermal catalysis, photocatalysis, and electrocatalysis. 27–32 ?>The preparation of molybdenum carbide is usually performed under high temperatures (≥700 °C), leading to the formation of products with a large size, 33 which is harmful to the exposure of active sites. Moreover, the high synthesis temperature of molybdenum carbide is not beneficial for the construction of intimate contact with organic semiconductors (such as g-C 3 N 4 ) owing to the relatively low decomposition temperature.…”

“…Molybdenum carbide has the merits of a Pt-like electronic structure, good electrical conductivity, and excellent thermal and chemical stability, enabling it to be widely applied in the fields of thermal catalysis, photocatalysis, and electrocatalysis. [27][28][29][30][31][32] ? † Electronic supplementary information (ESI) available.…”