Uncovering the Role of Countercations in Ligand Exchange of WSe2: Tuning the d-Band Center toward Improved Hydrogen Desorption
| Autor: | Yeseul Hong, Viet Q. Bui, Meeree Kim, Sohyeon Seo, Hyoyoung Lee, Yunhee Cho, Yoshiyuki Kawazoe, G. Hwan Park |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Ligand Fermi level 02 engineering and technology Overpotential 010402 general chemistry 021001 nanoscience & nanotechnology Photochemistry Antibonding molecular orbital Electrochemistry 01 natural sciences 0104 chemical sciences Catalysis chemistry.chemical_compound symbols.namesake chemistry Transition metal Oleylamine symbols General Materials Science 0210 nano-technology |
| Zdroj: | ACS Applied Materials & Interfaces. 13:11403-11413 |
| ISSN: | 1944-8252 1944-8244 |
| Popis: | The role of countercations that do not bind to core nanocrystals (NCs) but rather ensure charge balance on ligand-exchanged NC surfaces has been rarely studied and even neglected. Such a scenario is unfortunate, as an understanding of surface chemistry has emerged as a key factor in overcoming colloidal NC limitations as catalysts. In this work, we report on the unprecedented role of countercations in ligand exchange for a colloidal transition metal dichalcogenide (TMD), WSe2, to tune the d-band center toward the Fermi level for enhanced hydrogen desorption. Conventional long-chain organic ligands, oleylamine, of WSe2 NCs are exchanged with short atomic S2- ligands having countercations to preserve the charge balance (WSe2/S2-/M+, M = Li, Na, K). Upon exchange with S2- ligands, the charge-balancing countercations are intercalated between WSe2 layers, thereby serving a unique function as an electrochemical hydrogen evolution reaction (HER) catalyst. The HER activity of ligand-exchanged colloidal WSe2 NCs shows a decrease in overpotential by down-shift of d-band center to induce more electron-filling in antibonding orbital and an increase in the electrochemical active surface area (ECSA). Exchanging surface functionalities with S2- anionic ligands enhances HER kinetics, while the existence of intercalated countercations improves charge transfer with the electrolyte. The obtained results suggest that both anionic ligands and countercationic species in ligand exchange must be considered to enhance the overall catalytic activity of colloidal TMDs. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|