Direct Synthesis of Large‐Area 2D Mo₂C on In Situ Grown Graphene

Abstract

As a new member of the MXene group, 2D Mo C has attracted considerable interest due to its potential application as electrodes for energy storage and catalysis. The large-area synthesis of Mo C film is needed for such applications. Here, the one-step direct synthesis of 2D Mo C-on-graphene film by molten copper-catalyzed chemical vapor deposition (CVD) is reported. High-quality and uniform Mo C film in the centimeter range can be grown on graphene using a Mo-Cu alloy catalyst. Within the vertical heterostructure, graphene acts as a diffusion barrier to the phase-segregated Mo and allows nanometer-thin Mo C to be grown. Graphene-templated growth of Mo C produces well-faceted, large-sized single crystals with low defect density, as confirmed by scanning transmission electron microscopy (STEM) measurements. Due to its more efficient graphene-mediated charge-transfer kinetics, the as-grown Mo C-on-graphene heterostructure shows a much lower onset voltage for hydrogen evolution reactions as compared to Mo C-only electrodes.

Two‐Dimensional Transition Metal Carbides and Nitrides (MXenes): Synthesis, Properties, and Electrochemical Energy Storage Applications

“…Importantly, the α‐Mo 2 C crystals showed a crystal thickness‐dependent superconductivity and strong anisotropy with magnetic field orientation . In another report by Geng et al, a molten Mo‐Cu alloy catalyst was used in the CVD process to grow well‐faceted Mo 2 C single crystals on graphene. The Mo 2 C crystals were ~50–100 μm in width and ~8 nm in thickness and were vertically aligned on graphene .…”

“…In another report by Geng et al, a molten Mo‐Cu alloy catalyst was used in the CVD process to grow well‐faceted Mo 2 C single crystals on graphene. The Mo 2 C crystals were ~50–100 μm in width and ~8 nm in thickness and were vertically aligned on graphene . During the growth, graphene could passivate the catalyst surface and prevent the Mo atoms from reacting with methane, resulting in a change of growth mechanism from precipitation‐limited to diffusion‐limited process.…”

Insights into the Electrocatalytic Hydrogen Evolution Reaction Mechanism on Two‐Dimensional Transition‐Metal Carbonitrides (MXene)

“…Experimentally,Mo 2 CMXene have been proved to exemplify high HER activity,b ut the overpotential reached up to 0.283 V. [26] In order to broaden the applications of Mo 2 C, large-area 2D Mo 2 Co n graphene was synthesized and it unveiled ar elatively low overpotential of 87 mV compared to the previous work. [27] More recently,Y uan et al reported that MXene nanofibers exhibited excellent electrocatalytic HER activity due to the presence of ample active sites in materials surface, thusi mplying that Ti-based MXene renders am agnificent prospect in the energy application. [28] Furthermore, theoretical study indicated that the HER catalytic activity of MXenes can be facilely tuned by controlling the layer thickness and Oc overage.…”

Porous Molybdenum Carbide Nanostructures Synthesized on Carbon Cloth by CVD for Efficient Hydrogen Production

“…[26][27][28] Density functionalt heory (DFT) calculations showed that the hybridizationb etween do rbitals of metal molybdenum and sa nd po rbitals of carbon broadened of the dband of Mo 2 C, and thus led to as imilard -band structure to Pt. [29][30][31][32] The Pt-like electronic structure of Mo 2 Cm akei ta promising substitute for expensive Pt-based catalysts.Conventionally,M o 2 Cw as synthesized by temperature programmed reduction methods with gas-solid reactionsb etween metal, [33,34] or metal-oxides olids, [35][36][37] and carbon-rich gases (e.g.,C H 4 /H 2 ,C O/H 2 ,C 2 H 6 /H 2 ,e tc.). However,e xcessive carbon tendst ob edeposited from the carbon-containing gases and lead to polymeric carbon speciesc overed active sites, which could reducet he HERe lectrocatalytic activity.…”

“…Conventionally,M o 2 Cw as synthesized by temperature programmed reduction methods with gas-solid reactionsb etween metal, [33,34] or metal-oxides olids, [35][36][37] and carbon-rich gases (e.g.,C H 4 /H 2 ,C O/H 2 ,C 2 H 6 /H 2 ,e tc.). However,e xcessive carbon tendst ob edeposited from the carbon-containing gases and lead to polymeric carbon speciesc overed active sites, which could reducet he HERe lectrocatalytic activity.…”