Covalent Surface Functionalization of Exfoliated MoS₂ Nanosheets for Improved Electrocatalysis

Author(s)

Hostert, Leandro ; Dias, Matheus S. ; de Aquino, Caroline B. ; dos Santos, Felipe C. ; Marangoni, Valeria S. ; Silva, Cecilia De Carvalho C. ; Seixas, Leandro ; Maroneze, Camila M.

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. N/A, p. 10-pg., 2024-11-13.

Abstract

Transition metal dichalcogenides, particularly the metallic phase of molybdenum disulfide (1T'-MoS2), have attracted significant attention as promising nonprecious metal electrocatalysts for the hydrogen evolution reaction (HER) due to their appealing electrochemical properties and optimal hydrogen adsorption free energy (Delta G H). In this study, we used a combined theoretical and experimental approach to investigate the covalent functionalization of MoS2 with -CH2COOH groups. Notably, the presence of Mo oxidized species(MoO x ) was significantly diminished in the functionalized material, suggesting a potential protective role of the functional groups against MoS2 oxidation. Additionally, our findings show a decrease in the proportion of the metallic 1T' phase upon functionalization (58% for MoS2/CH2COOH compared to 74% for Exf-MoS2). However, electrochemical measurements unveil a remarkable enhancement in electrocatalytic activity upon the integration of -CH2COOH groups, as evidenced by observations from Linear Sweep Voltammetry (LSV) and Electrochemical Impedance Spectroscopy (EIS). In LSV analysis, a substantial 53% reduction in the Tafel slope is observed, declining from -145 mV dec-1 (for Exf-MoS2) to -77 mV dec-1 (for MoS2/CH2COOH). Additionally, EIS measurements indicate a significant decrease in charge transfer resistance, dropping from 82.03 +/- 0.11 k Omega/cm2 (for Exf-MoS2) to 12.41 +/- 0.01 k Omega/cm2 (for MoS2/CH2COOH). The integration of these functional groups onto the MoS2 surface demonstrates remarkable effectiveness in inhibiting oxidation while concurrently leading to a noteworthy enhancement of catalytic activity for the HER. (AU)

• FAPESP's process: 22/14549-3 - Intelligible high-entropy materials: developing models, data and applications
• Grantee: Leandro Seixas Rocha
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/20799-1 - Van der Waals heterostructure architectures in liquid media: application in photonic devices
• Grantee: Valeria Spolon Marangoni
• Support Opportunities: Scholarships in Brazil - Post-Doctoral