Photocatalytic hydrogen generation on low-bandgap black zirconia (ZrO) produced by high-pressure torsion

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 8; no. 7; pp. 3643 - 365
• Main Authors: Wang, Qing, Edalati, Kaveh, Koganemaru, Yuta, Nakamura, Shohei, Watanabe, Motonori, Ishihara, Tatsumi, Horita, Zenji
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2020
• Subjects: Catalytic activity; Clean energy; Clean technology; Conduction; Conduction bands; Crystal defects; Electromagnetic absorption; Electronics industry; Energy gap; Energy sources; Hydrogen; Hydrogen evolution; Hydrogen production; Lattice vacancies; Oxygen; Phase transitions; Photocatalysis; Photocatalysts; Pressure; Solar energy; Water splitting; Zirconia; Zirconium dioxide
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta11839j

Photocatalysis on semiconductors using solar energy sources provides a clean technology to produce hydrogen from water splitting. Although zirconia (ZrO 2 ) is a semiconductor oxide, it is not generally considered as a photocatalyst owing to its poor light absorbance and wide bandgap (over 5 eV). In this study, black ZrO 2 with a large concentration of lattice defects such as oxygen vacancies, dislocations and nanograin boundaries is stabilized by high-pressure torsion (HPT) straining. The black ZrO 2 , which experiences monoclinic-tetragonal phase transformations during the HPT process, shows large light absorption, a small bandgap, reduced conduction band energy and high photocatalytic activity for hydrogen evolution due the presence of oxygen vacancies. These results confirm that the introduction of strain-induced oxygen vacancies is a potential method to produce low-bandgap photocatalysts. Photocatalytic hydrogen generation on low-bandgap black ZrO 2 produced by high-pressure torsion.