Ultrasmall and phase-pure W2C nanoparticles for efficient electrocatalytic and photoelectrochemical hydrogen evolution

Abstract

Earlier research has been primarily focused on WC as one of the most promising earth-abundant electrocatalysts for hydrogen evolution reaction (HER), whereas the other compound in this carbide family—W2C—has received far less attention. Our theoretical calculations suggest that such a focus is misplaced and W2C is potentially more HER-active than WC. Nevertheless, the preparation of phase pure and sintering-free W2C nanostructures represents a formidable challenge. Here we develop an improved carburization method and successfully prepare ultrasmall and phase-pure W2C nanoparticles. When evaluated for HER electrocatalysis, W2C nanoparticles exhibit a small onset overpotential of 50 mV, a Tafel slope of 45 mV dec−1 and outstanding long-term cycling stability, which are dramatically improved over all existing WC-based materials. In addition, the integration of W2C nanoparticles with p-type Si nanowires enables highly active and sustainable solar-driven hydrogen production. Our results highlight the great potential of this traditionally non-popular material in HER electrocatalysis.

Molybdenum Carbide‐Oxide Heterostructures: In Situ Surface Reconfiguration toward Efficient Electrocatalytic Hydrogen Evolution

“…In the Mo=O mode, the Δ G H* on Mo‐site 1, 2, 3 and 4 is −0.236, −0.260, −0.266 and −0.238 eV, respectively. Such values are obviously higher than that on Mo 2 C (101) and approach to Δ G H* =0, which makes H* desorption more easy and thereby promotes HER kinetics . As for the Mo−O−Mo mode, the Δ G H* on Mo sites unfortunately decreases to more negative values (−0.421, −0.457, −0.542 and −0.395 eV), suggesting disfavoured HER on the oxygen bridged Mo 2 C surface.…”

Universal Surface Engineering of Transition Metals for Superior Electrocatalytic Hydrogen Evolution in Neutral Water

“…30 It is shown that an adsorption free energy of hydrogen (ΔGH) close to zero usually results in high performance for H2 evolution at pH 0. 33 Based on our DFT calculations, it is found that the nitrogen atom in N-Ni leads to a stronger interaction of proton on N-Ni than on Ni framework ( Figure S15), which is disadvantageous to HER under acidic condition. Therefore, rather than improved but decreased HER activity would be expected for N-Ni compared to Ni framework at pH 0.…”

Ultrafine Molybdenum Carbide Nanocrystals Confined in Carbon Foams via a Colloid‐Confinement Route for Efficient Hydrogen Production

“…To compare the catalytic activity of the uf‐Mo 2 C/CF with those of the recently reported for molybdenum‐carbide‐based and tungsten‐carbide‐based HER catalysts, the overpotentials required to drive 10 mA cm −2 (η 10 ) and the Tafel slopes for HER are summarized in Figure d (also see Tables S2–S4 for more details, Supporting Information). Notably, while some transition metal carbide‐based electrocatalysts exhibit a lower η 10 and Tafel slope than those of the uf‐Mo 2 C/CF catalyst, some of these catalysts might be contaminated with Pt due to usage of Pt counter electrode . Even so, the uf‐Mo 2 C/CF catalyst still remains one of the best HER catalysts in the whole pH range, particularly when the neutral electrolyte is used.…”