Understanding the fundamental electrical and photoelectrochemical behavior of a hematite photoanode

Author(s)

Soares, Mario R. S. ; Goncalves, Ricardo H. ; Nogueira, Icamira C. ; Bettini, Jefferson ; Chiquito, Adenilson J. ; Leite, Edson R.

• Document type: Journal article
• Source: Physical Chemistry Chemical Physics; v. 18, n. 31, p. 21780-21788, AUG 31 2016.
• Web of Science Citations: 10

Abstract

Hematite is considered to be the most promising material used as a photoanode for water splitting and here we utilized a sintered hematite photoanode to address the fundamental electrical, electrochemical and photoelectrochemical behavior of this semiconductor oxide. The results presented here allowed us to conclude that the addition of Sn4+ decreases the grain boundary resistance of the hematite polycrystalline electrode. Heat treatment in a nitrogen (N-2) atmosphere also contributes to a decrease of the grain boundary resistance, supporting the evidence that the presence of oxygen is fundamental for the formation of a voltage barrier at the hematite grain boundary. The N-2 atmosphere affected both doped and undoped sintered electrodes. We also observed that the heat treatment atmosphere modifies the surface states of the solid-liquid interface, changing the charge-transfer resistance. A two-step treatment, with the second being performed at a low temperature in an oxygen (O-2) atmosphere, resulted in a better solid-liquid interface. (AU)

• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC