While alkaline water electrolysis represents a highly promising and sustainable pathway for hydrogen production, its widespread application is hindered by the sluggish kinetics of the hydrogen evolution reaction (HER) due to a large energy barrier for water dissociation. In this work, a heterogeneous electrocatalyst of Ru/MoC-Mo 2 C@NC was prepared by uniformly embedding ruthenium nanoparticles within a nitrogen-doped carbon matrix hosting MoC-Mo 2 C heterojunctions. (MoC-Mo 2 C@NC). Electrochemical experimental results demonstrate the remarkably boosted HER catalytic performance of Ru/MoC-Mo 2 C@NC compared with Ru/NC, Ru/MoC@NC and Ru/Mo 2 C@NC by presenting the lowest overpotential of 18.5 mV at 10 mA cm −2 and Tafel slope of 61.71 mV·dec −1 , along with superior intrinsic activity and mass specific activity. Density-functional theory calculations further reveal that the enhanced electronic metal-support interaction (EMSI) between Ru sites and the MoC-Mo 2 C@NC support in Ru/MoC-Mo 2 C@NC induces significant charge redistribution and interface charge accumulation in Ru/MoC-Mo 2 C@NC, thereby optimizing water dissociation energy barrier and hydrogen adsorption free energy (ΔG H∗ ). Meanwhile, this reinforced EMSI facilitates efficient reverse hydrogen spillover at the Ru/MoC-Mo 2 C@NC interface, which further favors water dissociation on Mo sites and hydrogen desorption on Ru sites of Ru/MoC-Mo 2 C@NC. These regulating effects collectively accelerate the hydrogen intermediate transport and enhance the overall HER kinetics. This work provides valuable insights into enhanced electronic metal-support interaction on a heterostructure catalytic system optimizing both water dissociation and reverse hydrogen spillover for designing highly efficient water electrolysis catalysts.
The serious problem of carbon monoxide (CO) poisoning on the surface of Pt-based catalysts has long constrained the commercialization of proton exchange membrane fuel cells (PEMFCs). Regeneration of Pt sites by maintaining CO scavenging ability through precise construction of the surface and interface structure of the catalyst is the key to obtaining high-performance CO-resistant catalysts. Here, we used molybdenum carbide (MoC x ) as the support for Pt and introduced Ru single atoms (SA-Ru) at the Pt-MoC x interface to jointly decrease the CO adsorption strength on Pt. More importantly, the MoC x and SA-Ru are immune to CO poisoning, which continuously assists in the oxidation of adsorbed CO by generating oxygen species from water dissociation. These two effects combine to confer this anode catalyst (SA-Ru@Pt/MoC x ) remarkable CO tolerance and the ability to operate stably in fuel cell with high CO concentration (power output 85.5 mW cm −2 @20,000 ppm CO + H 2 – O 2 ), making it possible to directly use the cheap reformed hydrogen as the fuel for PEMFCs.
High-entropy carbides (HECs) possess superior properties such as favorable corrosion resistance and marvelous hardness and are widely applied in specific extreme environments. Herein, a novel method was proposed for synthesizing HECs powders with raw materials of corresponding oxides and carbon black, which was composed of steps of ball-milling in stainless jar, carbothermic reduction at 1873 K, as well as the following calcium posttreatment at 1273 K to remove residual carbon by generating CaC 2 . Finally, pure HECs powders could be fabricated after acid leaching treatment. Under the current experimental conditions, besides HfC-TaC-ZrC-NbC quaternary system, a homogeneous solid solution could be fabricated by adding Mo or/and Ti, but it could not be achieved for systems with addition of V, W, or Cr, owing to the low lattice constant or different crystal structure of corresponding carbides. In the reduction step, iron resulted from ball milling process acted as the diffusion channel to promote the mutual diffusion of different components. Meanwhile, the calcium treatment temperature had a weak effect on particle size of HEC powders. HfC-TaC-ZrC-NbC-MoC-TiC powders prepared at the calcium posttreatment temperature of 1273 K had an oxygen content of .302% and an average grain size of 252 nm.
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