Investigating the thermally induced p-n transition in reduced graphene oxide layers exposed to hydrogen sulfide

Author(s)

Ruiz, Elisa ; Varenne, Christelle ; De Lima, Bruno S. ; Gueye, Thiaka ; Pauly, Alain ; Mastelaro, Valmor R. ; Brunet, Jerome ; Ndiaye, Amadou L.

• Document type: Journal article
• Source: SENSORS AND ACTUATORS B-CHEMICAL; v. 409, p. 10-pg., 2024-03-14.

Abstract

To investigate the origin of the p -n transition observed in graphene-based materials for chemical sensors, we developed sensing layers made of chemically reduced graphene oxide (rGO), prepared from graphene oxide (GO) using citrate as a reducing agent. We focused mainly on the thermally induced p -n transition when the sensing layers are exposed to H2S at a specific temperature. The rGO sensing layers are prepared through drop casting on interdigitated electrodes. Scanning electron and transmission electron microscopes allow the characterization of the rGO structure, while FTIR, X-ray photoelectron spectroscopy, and electrical characterization have revealed the reduction efficiency. The p -n transition occurs between 80 degrees C and 90 degrees C, whatever the resistance range and the exposition history to H2S. The temperature -dependent transition, which starts around 80-90 degrees C, is reversible if the temperature is kept below 80 degrees C, i.e., the rGO remains p -type material. When experiments are performed at a temperature above 90 degrees C, the transition from p -type to n -type takes place, and the n -type persists, showing an irreversible transition. The transition starts gradually at 80 degrees C during lower concentration exposure and ends at high concentration. Finally, the results show that temperature and H2S contribute to the inversion of the initial charge carriers. (AU)

• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 18/07517-2 - Graphene and metal oxides composites: application as toxic gas sensors
• Grantee: Bruno Sanches de Lima
• Support Opportunities: Scholarships in Brazil - Post-Doctoral