Combined Theoretical and Experimental Investigations of Atomic Doping To Enhance Photon Absorption and Carrier Transport of LaFeO3 Photocathodes

• Published in: Chemistry of materials Vol. 31; no. 15; pp. 5890 - 5899
• Main Authors: Wheeler, Garrett P, Baltazar, Valentin Urena, Smart, Tyler J, Radmilovic, Andjela, Ping, Yuan, Choi, Kyoung-Shin
• Format: Journal Article
• Language: English
• Published: American Chemical Society 13.08.2019
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.9b02141

Perovskite-type lanthanum iron oxide, LaFeO3, is a p-type semiconductor that can achieve overall water splitting using visible light while maintaining photostability. These features make LaFeO3 a promising photocathode candidate for various photoelectrochemical cells. Currently, the photoelectrochemical performance of a LaFeO3 photocathode is mainly limited by considerable bulk electron–hole recombination. This study reports a combined theoretical and experimental investigation on the atomic doping of LaFeO3, in particular, substitutional doping of La3+ with K+, to increase its charge-transport properties and decrease electron–hole recombination. The computational results show that K-doping enhances not only the charge-transport properties but also photon absorption below the bandgap energy of the pristine LaFeO3. The effect of K-doping was systematically investigated by comparing the electronic and atomic structures, majority carrier density, hole-polaron formation, and optical properties of pristine and K-doped LaFeO3. The computational results were then verified by experimentally characterizing the crystal structures, compositions, optical properties, and photoelectrochemical properties of LaFeO3 and K-doped LaFeO3 electrodes. For this purpose, pristine LaFeO3 and K-doped LaFeO3 were prepared as high-surface-area, high-purity photoelectrodes having the same morphology to accurately and unambiguously evaluate the effect of K-doping. The combined computational and experimental investigations presented in this study provide useful insights into the effect of composition tuning of LaFeO3 and other p-type oxides with a perovskite structure.