Computationally Guided Design to Accelerate Discovery of Doped β-Mo₂C Catalysts toward Hydrogen Evolution Reaction

Abstract

Low-cost molybdenum carbides have shown a rapid increase in their efficiency toward catalyzing the hydrogen evolution reaction (HER) owing to their structural flexibility for metal doping and nanostructure engineering. Herein, we employ first-principles quantum mechanical calculations in conjunction with thermodynamic analysis to shortlist ideal single-metal dopants that improve HER catalytic activity of β-Mo2C. We show that Ir or Ti substitutional doping at the Mo sites of β-Mo2C introduces thermoneutral hydrogen adsorption sites for HER, while the other elements in the first-row transition metals and Pt and Ag are not effective dopants for HER. To validate the computational results, we employ a microwave-assisted solvothermal method to synthesize metal-doped β-Mo2C nanoparticles (NPs) and assess their HER performance and structure using a suite of electrochemical and ex situ structural characterizations. From cyclic voltammetry, we find that the HER onset voltage of pristine β-Mo2C NPs decreases by more than 20% through impurity doping with Ti or Ir and is accompanied by a discernable increase in exchange current density. Transmission electron microscopy (TEM), high-angle annular dark-field scanning TEM (HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDS) confirm that such an increase in HER activities originates from impurity doping and is not due to morphological or phase changes of the catalyst. The present study demonstrates that a combined and synergistic experimental and computational approach is indispensable to uncover the atomistic origins of catalytic activity and provide a rational design of the catalyst.

High hydrogen evolution activities of dual-metal atoms incorporated N-doped graphenes achieved by coordination regulation

“…All these parameters have been carefully tested in our recent work [44] . All the results were visualized with the aid of the VESTA software [45] .…”

SACs on Non‐Carbon Substrates: Can They Outperform for Water Splitting?

“…2) The incorporation of single atoms redistributes the electron density leading to the optimization of reaction free energy profile due to the strong covalent interaction. For example, Lee and co‐workers predicted the HER activities of 12 types of metal atoms (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Ir and Pt) doped β‐Mo 2 C. [ 183 ] Ir and Ti atoms substitutional doping at Mo sites greatly activated the thermodynamic HER activity of β‐Mo 2 C, while the other metals were not the effective dopants. Ti‐, Mo‐, and V‐based SACs have also been well explored as HER electrocatalysts to form a large group for substituting Pt catalyst.…”

Phase Engineering and Synchrotron-Based Study on Two-Dimensional Energy Nanomaterials

“…Various strategies, such as CVD, electrochemical deposition, impregnation, hydro/solvothermal, template-assisted pyrolysis, among others, have been employed to introduce dopants in 2D materials. − Understanding the formation mechanism of atomic doping in these methods is crucial for designing high-performance 2D energy materials. To accomplish this, advanced ex situ and in situ synchrotron-radiation characterization techniques can be used to explore the evolution of dopants and host materials during synthesis.…”