Structure Confined Porous Mo₂C for Efficient Hydrogen Evolution

Abstract

Molybdenum carbide (Mo 2 C) has been widely applied in energy conversion, electrocatalysis, and other electronic devices, but its nanostructure with certain morphology and porous structure is tough to control. In this work, 1D or 2D porous Mo 2 C nanostructures can be synthesized by carburizing cobalt-based zeolitic imidazolate framework (ZIF-67) cladding MoO 3 nanowires or nanosheets hybrid structure under high temperature. The obtained 2D porous Mo 2 C shows a low onset overpotential (η = 25 and 36 mV) and a small Tafel slope (40 and 47 mV dec −1 ) in 0.1 m HClO 4 and 0.1 m KOH as well as great stability. This work highlights a new strategy for the design and synthesis of porous nanostructure Mo 2 C electrocatalysts. and 1D nanowires. The approach is through carburizing cobalt or zinc-based zeolite-type metal-organic framework (MOF) (ZIF-67 or ZIF-8) cladding MoO 3 nanosheets or nanowires under high temperature. The resulting nanostructures are periodically porous, largely preserving the precursor morphology. The porous Mo 2 C materials may provide an exceptionally large number of active sites. For instance, 2D Mo 2 C nanosheets may show excellent catalytic performance for hydrogen evolution over a broad range of pH value (0.1 m HClO 4 and 0.1 m KOH), including a low onset overpotential (η = 25 and 36 mV vs RHE), a small Tafel slope (40 and 47 mV dec −1 ), and remarkable stability.

Structural Design and Electronic Modulation of Transition‐Metal‐Carbide Electrocatalysts toward Efficient Hydrogen Evolution

“…The nanowires afforded an η 10 of ≈130 mV, and a Tafel slope of 53 mV decade −1 in 0.5 m H 2 SO 4 , superior to the commercial Mo 2 C in micrometer (Figure c) . Meanwhile, the superior HER activity of nanowires to 3D and 2D nanostructures composed of similar Mo 2 C (Figure d) verified the promotion by 1D hierarchical architecture, consistent with the observation in other reports . To further improve the nanoporosity in 1D Mo 2 C, this research group recently developed an assisted pyrolysis of MoO x /DMF (DMF: N , N ‐dimethylformamide) with β‐cyclodextrin .…”

“…To improve the exposure, accessibility, and conductivity of TMC nanoparticles, the designed assemblies, such as porous or anisotropic architectures, are desired . In particular, 1D nanostructures hierarchically composed of TMCs are of significance because the hierarchical surface in radial direction provides abundant sites for H 2 generation and bubble release, and the axial dimension in micrometer facilitates charge transfer and avoids agglomeration of active components ( Figure a) .…”

Transition Metal Carbide Complex Architectures for Energy‐Related Applications

“…The main routes to prepare these non‐layered nanoplates and nanosheets are template‐based methods. Some inorganics with 2D nanoarchitecture are employed as the templates for designing TMC nanosheets . For example, MoO 3 nanosheets, prepared by a hydrothermal process, were used as the template for the preparation of 2D porous Mo 2 C nanosheets.…”

“…MoO 3 nanosheets were first covered with ZIF‐67 to form MoO 3 @ZIF‐67 hybrid nanosheets, which then were subjected to a carbonization procedure to obtain 2D porous Mo 2 C nanosheets. The 2D porous Mo 2 C nanosheets show low onset overpotentials and small Tafel slopes in both acid and basic electrolytes (Figure a–c) . Furthermore, VC/C nanosheets were synthesized by using V 2 O 5 nanosheets as both the template and precursor.…”

Creating Competitive Active Sites on CNTs Walls by N‐Doping and Sublayer Co4N Encapsulating for Efficient Hydrogen Evolution Reaction

“…It is imperative to develop a low‐cost hydrogen evolution reaction (HER) catalyst . Transition metals alloys and transition metals compounds, such as metal alloys, metal phosphide, metal nitride, metal carbide, and metal sulfide/fluoride with defect have shown their outstanding HER catalysis activity. Carbon materials such as heteroatom‐doped graphene, C 3 N 4 @N doped graphene and metal‐free covalent organic polymer (COPs) also showed excellent catalytic ability for hydrogen evolution reaction with easily prepared process.…”