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Coverage Effects on Hydrogen Evolution across Metals, Oxides, MXenes, and Dichalcogenides
Mauricio Mocelim1, Rafael L H Freire1, Pedro Ivo R Moraes1
1São Carlos Institute of Chemistry, University of São Paulo, Av. Trabalhador São-Carlense 400, São Carlos, São Paulo 13560-970, Brazil.
ACS Omega
|June 29, 2026
Summary
Hydrogen adsorption on electrocatalysts is crucial for the hydrogen evolution reaction. This study reveals that hydrogen coverage significantly impacts catalyst performance, contrary to previous dilute-limit assumptions, necessitating coverage-dependent analysis.
Area of Science:
- Materials Science
- Surface Chemistry
- Computational Chemistry
Background:
- Hydrogen adsorption thermodynamics are vital for hydrogen evolution reaction (HER) electrocatalyst activity.
- First-principles studies often neglect lateral adsorbate interactions by focusing on dilute H binding, which is unrealistic for operating conditions.
Purpose of the Study:
- To systematically investigate the impact of coverage-dependent hydrogen adsorption on diverse HER materials.
- To compare lateral H-H interactions across metallic, oxide, MXene, and 2D semiconductor systems.
Main Methods:
- Density functional theory (DFT) calculations were employed.
- Hydrogen adsorption was studied on Pt(111), α-Ir2O3(0001), Mo2CO2, and 1H-MoS2.
- Surface supercell size variation was used to control effective hydrogen coverage.
Main Results:
- Hydrogen adsorption on Pt(111) quickly converges due to metallic screening.
- Mo2CO2 exhibits significant coverage sensitivity, altering adsorption energetics.
- α-Ir2O3(0001) and 1H-MoS2 show coverage-dependent depolarization effects, impacting work function and electronic structure.
Conclusions:
- Hydrogen coverage is a critical descriptor for evaluating HER catalysts.
- Dilute-limit approximations in theoretical studies have limitations.
- Incorporating coverage effects is essential for accurate theoretical assessments of HER catalysts across various material classes.
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