β-Mo₂C Nanoparticles Produced by Carburization of Molybdenum Oxides with Carbon Black under Microwave Irradiation for Electrocatalytic Hydrogen Evolution Reaction

Abstract

The synthesis of electrochemically active β-Mo 2 C nanoparticles for hydrogen production was achieved by a fast and energy-efficient microwave-assisted carburization process from molybdenum oxides and carbon black. With the use of microwavebased production methods, we aim to reduce the long-time high-temperature treatments and the use of hazardous gases often seen in traditional molybdenum carbide synthesis processes. In our process, carbon black not only serves as a carbon source but also as a susceptor (microwave absorber) and conductive substrate. The irradiation power, reaction time, and Mo:C ratio were optimized to achieve the highest electrocatalytic performance toward hydrogen production in an acidic electrolyte. A complete transformation of MoO 3 to β-Mo 2 C nanoparticles and an additional graphitization of the carbon black matrix were achieved at 1000 W, 600 s, and Mo:C ratio above 1:7.5. Under these conditions, the optimized composite exhibited an excellent HER performance (η 10 = 156 mV, Tafel slope of 53 mV•dec −1 ) and large turnover frequency per active site (3.09 H 2 •s −1 at an overpotential of 200 mV), making it among the most efficient non-noble-metal catalysts. The excellent activity was achieved thanks to the abundance of β-Mo 2 C nanoparticles, the intimate nanoparticle-substrate interface, and enhanced electron transport toward the carbon black matrix. We also investigated the flexibility of the synthesis method by adding additional Fe or V as secondary transition metals, as well as the effect of the substrate.

α-MoB2 Nanosheets for Hydrogen Evolution in Alkaline and Acidic Media

“…As a d-block element with multiple oxidation states, molybdenum and molybdenum-based inorganic materials covering oxides, carbides, nitrides, phosphides, , selenides, and sulfides − have drawn significant attention, and part of them are considered as promising candidates for hydrogen evolution reaction (HER) without precious metal catalysts due to advantages including low cost and facile synthesis. − On the other hand, metal borides are a kind of inorganic materials considered as potential electrocatalysts for the HER as well because of their high activity and stability. − The combination of these two materials has led to continuous interest in the evaluation of the HER performance of molybdenum boride materials. ,, …”

Sustainable Production of Molybdenum Carbide (MXene) from Fruit Wastes for Improved Solar Evaporation

“…This shows that the former has a good wetting property, which provides multiple hydrophilic channels for water molecules to flow, thereby speeding up the rate of water evaporation [18] . The high intensity ratio of the G and D bands (I G /I D ) observed from Raman measurements (Table S2), indicates that the 2D Mo 2 C CH photothermal layer possess a well‐organized interlayer channel compared to the other two Mo 2 C samples [13] . Notably, such highly ordered interlayer channel enables rapid water transportation [14] .…”

“…1350 cm À 1 and ca. 1580 cm À 1 , that corresponds to the characteristics of metal carbide [13]. The field emission scanning electron microscopy (FESEM) images (Figure2d-e) and transmission electron microscopy image (Figure2f) prove the obtained Mo 2 C CH sample possess a 2D sheet-like structure with a lateral size in micrometer scale.…”

“…[18] The high intensity ratio of the G and D bands (I G /I D ) observed from Raman measurements (Table S2), indicates that the 2D Mo 2 C CH photothermal layer possess a well-organized interlayer channel compared to the other two Mo 2 C samples. [13] Notably, such highly ordered interlayer channel enables rapid water transportation. [14] In addition, when compared to other Mo 2 C samples, the NLDFT pore size distribution of Mo 2 C CH sample also demonstrates a greater pore volume of micro-and mesopores (compare Figure 3b and Figure S7c-d).…”

Gentle Haulers of Lithium-Ion–Nanomolybdenum Carbide Fillers in Solid Polymer Electrolyte

“…Transition metal carbide/oxide heterojunction nanofillers can reduce the energy barrier for lithium-ion transference. They also increase the effective carrier concentration between the electrode and electrolyte interfaces. − …”