Heteroatom Doping of Molybdenum Carbide Boosts pH-Universal Hydrogen Evolution Reaction

Abstract

Tuning electronic structures through heteroatom doping to weaken the Mo–H binding strength and constructing larger specific surface areas are considered an effective strategy to improve the hydrogen evolution reaction (HER) activity on β-Mo2C in full pH range. In this report, a CH4 (10%)/H2 inducing universal method for the formation of heteroatom-doped (F, N, S, or B) β-Mo2C nanoparticles (NPs) with nanosized and clean surface supported on reduced graphene oxide (rGO) (Mo2E x C1–x /rGO, E = F, N, S, or B) is proposed. Doping with different heteroatoms introduced different promoting effects on Mo2C toward HER in the full pH range. The Mo2F x C1–x /rGO electrocatalysts show the best activity for HER in acidic, alkaline, and neutral media, with the onset overpotentials of 37, 45, and 105 mV, respectively, which achieve 10 mA cm–2 at overpotentials of only 95 mV in 1 M HClO4. More noteworthy is the fact that the Mo2F x C1–x /rGO electrocatalysts only require 232 and 397 mV of overpotentials to reach 400 mA cm–2 in acidic and alkaline solutions, respectively. Besides, the Mo2F x C1–x /rGO electrocatalysts only need 480 mV of overpotential to reach 200 mA cm–2 in neutral conditions. Meanwhile, larger specific surface areas with nanosized and clean surfaces also contribute to improving the performance of HER, especially Mo2F x C1–x /rGO. However, the promoting effect of HER by tuning the electronic structures through doping of B and S into Mo2C is very limited. Moreover, doped Mo2C-based electrocatalysts in this work show superior stabilities for HER in the full pH range.

Highly Mesoporous MoO3 Catalysts for Electrophilic Aromatic Substitution

“…Molybdenum forms the basis of many heterogeneous catalytic systems that are very effective in controlling the rate and selectivity of a wide range of organic transformation reactions. − Besides catalysis, molybdenum-based materials show great applications in energy storage, optoelectronics, gas sensors, adsorption, and electrochemistry among others. − Molybdenum oxides and molybdenum sulfides are the most frequently used catalysts, while bromide, boride, nitride, phosphide, and carbide systems have also gotten much attention recently . Molybdenum oxides provide a series of oxidation states from 0 to +6, which are widely used for electrophilic addition, oxidation, and coupling reactions .…”

Electrospinning Preparation of N, P Dual-Doped Molybdenum Carbide/Porous Carbon Fibers with Highly Improved Electrocatalytic Activity for Hydrogen Evolution Reaction

“…Especially, one-dimensional nanofibers and hierarchically porous structure are vital for an electrocatalyst to enhance mass and charge transfer and expose more active sites. ,− Therefore, convenient methods with simple procedures are desirable for the preparation of one-dimensional nanofibers with hierarchical pores. As a physical method, electrospinning is a much simple technology with less procedure to manufacture one-dimensional nanofibers controllably on a large scale. − …”

Dual Modification Strategy of Nickel Sulfide as pH-Universal Catalysts for Hydrogen Production at Large Current Density

“…Therefore, the development of alternative and high-energy-density renewable energy sources is urgent. − Hydrogen as an environmentally friendly and highly efficient renewable energy source has attracted wide attention. In recent years, the production of hydrogen by the electrolysis of water, that is, the half-reaction hydrogen evolution reaction (HER), is regarded as one of the most promising ways to extract high-purity hydrogen energy on a large scale. − Precious metal materials are currently recognized as the best electrocatalysts, but their practical applications are greatly limited because of their high price and scarce reserves. − In the past few decades, a variety of nonprecious metal electrocatalysts have been gradually discovered, including the transition metal chalcogenides, − nitrides, − phosphides, − and carbides. − Ni 3 S 2 , as a heazlewoodite mineral, shows an excellent conductivity and metallic property because of the plentiful Ni–Ni bonds. − In general, Ni 3 S 2 has the strong adsorption of hydrogen (H*) on Ni–Ni or Ni–S sites. It is not conducive to the desorption of H* to form the final H 2 .…”