Mo2C based electrocatalyst with nitrogen doped three-dimensional mesoporous carbon as matrix, synthesis and HER activity study

Recent progress of molybdenum carbide based electrocatalysts for electrocatalytic hydrogen evolution reaction

Electrocatalytic hydrogen evolution reaction (HER) is one of the most promising and clean strategies to prepare hydrogen on a large scale. Nevertheless, the efficiency of HER is greatly restricted by the large overpotential at the anode, and it is necessary to develop low cost electrocatalysts with excellent performance and stability. Molybdenum carbide has shown great potential in the field of HER due to its unique electronic structure and physical and chemical properties. In this paper, the current progress of molybdenum carbide-based catalysts for HER is summarized. The influence of phase structure, nanostructure, heterostructure and heteroatoms doping on its catalytic performance is discussed in detail. Especially, the catalytic mechanisms are analyzed according to structural characterization and theoretical calculation results. Finally, the challenges and prospects for the further development of molybdenum carbide-based catalysts for HER are put forward to guide the progress of this field.

Hierarchically Annular Mesoporous Carbon Derived from Phenolic Resin for Efficient Removal of Antibiotics in Wastewater

Antibiotics have become a new type of environmental pollutant due to their extensive use. High-performance adsorbents are of paramount significance for a cost-effective and environmentally friendly strategy to remove antibiotics from water environments. Herein, we report a novel annular mesoporous carbon (MCN), prepared by phenolic resin and triblock copolymer F127, as a high-performance adsorbent to remove penicillin, streptomycin, and tetracycline hydrochloride from wastewater. The MCNs have high purity, rich annular mesoporosity, a high surface area (605.53 m²/g), and large pore volume (0.58 cm³/g), improving the adsorption capacity and facilitating the efficient removal of penicillin, streptomycin, and tetracycline hydrochloride from water. In the application of MCNs to treat these three kinds of residual antibiotics, the adsorption amounts of tetracycline hydrochloride were higher than penicillin and streptomycin, and the adsorption capacity was up to 880.6 mg/g. Moreover, high removal efficiency (99.6%) and excellent recyclability were achieved. The results demonstrate that MCN adsorbents have significant potential in the treatment of water contaminated with antibiotics.

Molybdenum Carbide Anchored on N,S Co-Doped Carbon Composite Derived from Lignosulfonate as a High Performance Electrocatalyst for Hydrogen Evolution Reaction

A composite of Mo₂C nanoparticles dispersed onto a nitrogen and sulfur co-doped carbon scaffold (Mo₂C/N,S-C) was prepared by a simple and environmentally friendly method of one-pot annealing of MoCl₅, urea, and lignosulfonate under a N₂ atmosphere at 700 °C. Lignosulfonate, a by-product of the sulfite pulping process, was employed as a feedstock to fabricate the S-doped carbon scaffold and carbide simultaneously, and urea acted as a nitrogen source for N-doping to carbon. The as-prepared Mo₂C/N,S-C catalyst showed high performance for the hydrogen evolution reaction (HER), with a small overpotential of 105 mV at 10 mAcm^-2, and good stability for 3000 cycles. The improved HER performance of the Mo₂C/N,S-C originated from the interplay between the highly active Mo₂C nanoparticles and the N,S co-doped carbon scaffold with its high electrical conductivity and large surface area. Furthermore, N,S co-doping to carbon improved the hydrophilicity of the catalyst surface, thus further enhancing the HER activity.

Smart Designs of Mo Based Electrocatalysts for Hydrogen Evolution Reaction

As a sustainable and clean energy source, hydrogen can be generated by electrolytic water splitting (i.e., a hydrogen evolution reaction, HER). Compared with conventional noble metal catalysts (e.g., Pt), Mo based materials have been deemed as a promising alternative, with a relatively low cost and comparable catalytic performances. In this review, we demonstrate a comprehensive summary of various Mo based materials, such as MoO2, MoS2 and Mo2C. Moreover, state of the art designs of the catalyst structures are presented, to improve the activity and stability for hydrogen evolution, including Mo based carbon composites, heteroatom doping and heterostructure construction. The structure–performance relationships relating to the number of active sites, electron/ion conductivity, H/H2O binding and activation energy, as well as hydrophilicity, are discussed in depth. Finally, conclusive remarks and future works are proposed.

A three-dimensional self-standing Mo2C/nitrogen-doped graphene aerogel: Enhancement hydrogen production from landfill leachate wastewater in MFCs-AEC coupled system

A hydrothermal-annealing method was adopted to form nitrogen-doped graphene aerogel-supported molybdenum carbide (Mo₂C/NGA) materials by using graphene oxide (GO), poly (propylene glycol) bis(2-aminopropyl ether) (D400 for short) and ammonium molybdate as precursors. The annealing temperature and GO/D400 wt ratio played an important role on the materials structure and electrocatalytic activity. When the annealing temperature reached to 800 °C, the Mo₂C was formed as an active component and improved obviously the hydrogen evolution reaction (HER) activity. After introducing the appropriate amount of D400, the Mo₂C/NGA material not only had a firm porous monolithic framework, but also presented an increasing HER activity. Further, the Mo₂C/NGA-based microbial fuel cells-ammonia electrolysis cell (MFCs-AEC) coupled system was constructed and operated for higher hydrogen production. The coupled system produced hydrogen of 198 mL g^-1_Mo2C/NGA in simulated ammonia-rich wastewater. As using the actual landfill leachate wastewater as substrate, there was 79.2 mL g^-1_Mo2C/NGA of hydrogen production. All of these were attributed to the porous structure with an interconnected network and the nitrogen-doped structure of the NGA.

Synthesis of Mo2C and W2C Nanoparticle Electrocatalysts for the Efficient Hydrogen Evolution Reaction in Alkali and Acid Electrolytes

The synthesis of low cost, high efficacy, and durable hydrogen evolution electrocatalysts from the non-noble metal group is a major challenge. Herein, we establish a simple and inexpensive chemical reduction method for producing molybdenum carbide (Mo2C) and tungsten carbide (W2C) nanoparticles that are efficient electrocatalysts in alkali and acid electrolytes for hydrogen evolution reactions (HER). Mo2C exhibits outstanding electrocatalytic behavior with an overpotential of -134 mV in acid medium and of -116 mV in alkaline medium, while W2C nanoparticles require an overpotential of -173 mV in acidic medium and -130 mV in alkaline medium to attain a current density of 10 mA cm-2. The observed results prove the capability of high- and low-pH active electrocatalysts of Mo2C and W2C nanoparticles to be efficient systems for hydrogen production through HER water electrolysis.