Understanding the charge transport at hematite photoelectrodes interfaces

• Grant number: 17/25935-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Effective date (Start): April 09, 2018
• Effective date (End): April 08, 2019
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Flavio Leandro de Souza
• Grantee: André Luiz Martins de Freitas
• Supervisor: Yat Li
• Host Institution: Centro de Ciências Naturais e Humanas (CCNH). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil
• Research place: University of California, Santa Cruz (UC Santa Cruz), United States
• Associated to the scholarship: 14/11736-0 - Development of inorganic material nanostructures for conversion and storage of solar energy, BP.DD

Abstract

Hematite photoelectrode has been investigated as a good material to convert sunlight into chemical energy by water splitting. The wide visible wavelength absorption and thermodynamics stability in aqueous conditions provide an expected efficiency for this application. Nevertheless, the poor electronic transport and the short lifetime of photogenerated carriers hinder this material to achieve the best photoelectrochemical response. In this case, the doctoral project has been dedicated to use strategies to design hematite photoelectrodes with high performance to overcome the discussed limitations, as surface modification and incorporation of oxygen vacancies during heat treatment. The main proposal is to understand the transport properties on the solid-solid interface and solid-liquid interface. In the past few years, important characteristics of the produced hematite photoelectrodes in hydrothermal synthesis assisted by microwave radiation were determined by electrochemical and photoelectrochemical measurements. A synergetic effect of using oxygen-deficient atmosphere and surface modification with intermetallic elements was an important step to understand how donor density is increased. In this case, one of the main problems found it was the comprehension of the interface of hematite/electrolyte for oxygen evolution reaction. In order to clarify the transport properties, the proposal for this internship is to evaluate the photogenerated charges dynamics by transient absorption spectroscopy (TA), observing the transport mechanism for bare and modified hematite photoelectrodes and the implications at their interfaces. This proposal will be important to complement the study made until now by the student and his group. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

FREITAS, ANDRE L. M.; TOFANELLO, ARYANE; SOUZA, FLAVIO L.; LI, YAT. Insights on Thickness-Dependent Charge Transfer Efficiency Modulated by Ultrasonic Treatment in Hematite Photoanodes. Journal of Physical Chemistry C, v. 125, n. 18, p. 9981-9989, MAY 13 2021. (17/11986-5, 14/11736-0, 17/25935-3)