| Autor: |
Zappia, Marilena I., Bianca, Gabriele, Bellani, Sebastiano, Curreli, Nicola, Sofer, Zdeněk, Serri, Michele, Najafi, Leyla, Piccinni, Marco, Oropesa-Nuñez, Reinier, Marvan, Petr, Pellegrini, Vittorio, Kriegel, Ilka, Prato, Mirko, Cupolillo, Anna, Bonaccorso, Francesco |
| Rok vydání: |
2021 |
| Předmět: |
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| Zdroj: |
Journal Physical Chemistry C 2021, 125, 22, 11857-11866 |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1021/acs.jpcc.1c03597 |
| Popis: |
Two-dimensional (2D) transition-metal monochalcogenides have been recently predicted to be potential photo(electro)catalysts for water splitting and photoelectrochemical (PEC) reactions. Differently from the most established InSe, GaSe, GeSe, and many other monochalcogenides, bulk GaS has a large band gap of ca. 2.5 eV, which increases up to more than 3.0 eV with decreasing its thickness due to quantum confinement effects. Therefore, 2D GaS fills the void between 2D small-band-gap semiconductors and insulators, resulting of interest for the realization of van der Waals type-I heterojunctions in photocatalysis, as well as the development of UV light-emitting diodes, quantum wells, and other optoelectronic devices. Based on theoretical calculations of the electronic structure of GaS as a function of layer number reported in the literature, we experimentally demonstrate, for the first time, the PEC properties of liquid-phase exfoliated GaS nanoflakes. Our results indicate that solution-processed 2D GaS-based PEC-type photodetectors outperform the corresponding solid-state photodetectors. In fact, the 2D morphology of the GaS flakes intrinsically minimizes the distance between the photogenerated charges and the surface area at which the redox reactions occur, limiting electron-hole recombination losses. The latter are instead deleterious for standard solid-state configurations. Consequently, PEC-type 2D GaS photodetectors display a relevant UV-selective photoresponse. In particular, they attain responsivities of 1.8 mA W-1 in 1 M H2SO4 (at 0.8 V vs reversible hydrogen electrode -RHE-), 4.6 mA W-1 in 1 M Na2SO4 (at 0.9 V vs RHE), and 6.8 mA W-1 in 1 M KOH (at 1.1 V vs RHE) under 275 nm illumination wavelength with an intensity of 1.3 mW cm-2. |
| Databáze: |
arXiv |
| Externí odkaz: |
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