Benzyl Alcohol Photo-oxidation Based on Molecular Electronic Transitions in Metal Halide Perovskites
Jianbo Jin, Haowei Huang, Chubai Chen, Patrick W. Smith, Maria C. Folgueras, Sunmoon Yu, Ye Zhang, Pengcheng Chen, F. Seeler, Bernd Schaefer, Carlos Lizandara‐Pueyo, Rui Zhang, Kerstin Schierle‐Arndt, Peidong Yang
Abstract
Vacancy ordered double perovskites Cs 2 Te(IV)X 6 have been found to exhibit molecule-like electronic behavior when X is Cl – or Br – due to the zero-dimensional (0D) nature of their octahedral units. Electronically isolated building blocks, the [TeBr 6 ] 2– ionic octahedron, serve as the fundamental electronic unit of the Cs 2 TeBr 6 solid. Herein, a detailed understanding of the Cs 2 TeBr 6 electronic structure and its photoexcitation is presented with consideration of individual molecular orbitals from these isolated octahedral building blocks. Two optical absorption features correspond to two unique electronic transitions, (1) a highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) transition under 455 nm excitation and (2) mixed transitions including lower HOMO states to LUMO transition and HOMO to higher LUMO states transition under 365 nm excitation. With this in mind, we examined the excitation wavelength-dependent photo-oxidation of benzyl alcohol using Cs 2 TeBr 6 as the photocatalyst. Significant differences in photocatalytic performance were observed, and different forms of activated alcohol radicals were detected under the two excitation wavelengths. As a case study, this work highlights the application of molecule-like halide perovskites in photocatalysis. The highly tunable energy band structures and catalytic centers in perovskites can offer a valuable platform for photocatalytic mechanistic studies and catalyst development in the foreseeable future.