Material-Dependent Functionalization of CVD-Grown TMDC Monolayers Probed by Vibrational Nanospectroscopy
Maziar Jafari1, Amir Khojastehnezhad2, Seyed Faridedin Rafie3
1Department of Chemistry, Université Du Québec à Montréal (UQAM), Montréal, Québec, Canada.
Small (Weinheim an Der Bergstrasse, Germany)
|July 7, 2026
Summary
This study reveals how aryl diazonium salts covalently functionalize transition metal dichalcogenides (TMDCs) like MoSe2 and WSe2. Material and solvent choices significantly impact the reaction efficiency, offering a molecular-level understanding for 2D material modification.
Area of Science:
- Materials Science
- Surface Chemistry
- Nanotechnology
Background:
- Covalent functionalization of 2D semiconductors is crucial for tailored properties but lacks detailed molecular understanding.
- Transition metal dichalcogenides (TMDCs) offer unique electronic and optical properties, making their surface modification a key research area.
Purpose of the Study:
- To elucidate the molecular mechanisms of aryl diazonium salt covalent functionalization on monolayer TMDCs and their heterostructures.
- To investigate the influence of material composition (MoSe2, WSe2, heterostructures) and solvent environment on functionalization outcomes.
- To establish a nanoscale chemical framework for controlling TMDC surface modification.
Main Methods:
- Chemical Vapor Deposition (CVD) for growing TMDC monolayers and heterostructures.
- High-resolution scanning probe techniques: Tip-Enhanced Raman Spectroscopy (TERS) and Photo-induced Force Microscopy (PiFM).
- Atomistic molecular dynamics simulations to model precursor-surface interactions.
Main Results:
- TERS provided detailed nanospectroscopy of MoSe2-WSe2 nanodomains and heterojunctions.
- PiFM directly visualized aryl diazonium salt (4-carboxyphenyl and 4-nitrophenyl) covalent functionalization on TMDCs.
- Material-dependent reactivity was observed, with MoSe2 showing higher functionalization efficiency due to stronger precursor interactions and localization.
- Molecular dynamics simulations confirmed stronger interactions between 4-nitrobenzenediazonium cations and MoSe2, explaining experimental observations.
Conclusions:
- A molecular-level understanding of solvent- and material-dependent covalent functionalization of 2D TMDCs is established.
- The findings provide a framework for rational design of surface functionalization strategies for TMDCs.
- TERS and PiFM are powerful tools for nanoscale chemical analysis of 2D materials and their modifications.
Keywords:
covalent surface functionalizationinterfacial molecular dynamicsmaterial‐specific reactivitytwo‐dimensional (2D) materialsvibrational nanospectroscopy imaging
