Hematite Surface Activation by Chemical Addition of Tin Oxide Layer

Author(s)

Carvalho, Jr., Waldemir M. ; Souza, Flavio L.

• Document type: Journal article
• Source: ChemPhysChem; v. 17, n. 17, p. 2710-2717, SEP 5 2016.
• Web of Science Citations: 5

Abstract

In this study, the effect of tin (Sn4+) modification on the surface of hematite electrodes synthesized by an aqueous solution route at different times (2, 5, 10, 18, and 24h) is investigated. As confirmed from X-ray diffraction results, the as-synthesized electrode exhibits an oxyhydroxide phase, which is converted into a pure hematite phase after being subjected to additional thermal treatment at 750 degrees C for 30min. The tin-modified hematite electrode is prepared by depositing a solution of Sn4+ precursor on the as-synthesized electrode, followed by thermal treatment under the same abovementioned conditions. This modification results in an enhancement of the photocurrent response for all hematite electrodes investigated and attains the highest values of around 1.62 and 2.3mAcm(-2) at 1.23 and 1.4V versus RHE, respectively, for electrodes obtained in short synthesis times (2h). Contact angle measurements suggest that the deposition of Sn4+ on the hematite electrode provides a more hydrophilic surface, which favors a chemical reaction at the interface between the electrode and electrolyte. This result generates new perspectives for understanding the deposition of Sn4+ on the hematite electrode surface, which is in contrast with several studies previously reported; these studies state that the enhancement in photocurrent density is related to either the induction of an increased donor charge density or shift in the flat-band potential, which favors charge separation. (AU)

• FAPESP's process: 13/05471-1 - Effect of dopants in semiconductor nanostructures and their impact on photocatalytic performance
• Grantee: Waldemir Moura de Carvalho Junior
• Support Opportunities: Scholarships in Brazil - Doctorate
• 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: 11/19924-2 - Study and development of advanced novel materials: electronic, magnetic and nanostructured: an interdisciplinary approach
• Grantee: Carlos Rettori
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/50516-6 - Enhancing performance of artificial photosynthesis by engineered nanomaterials and photon management
• Grantee: Flavio Leandro de Souza
• Support Opportunities: Regular Research Grants