Bioluminescence-induced photocatalysis on semiconducting oxide nanosheets

ABSTRACT

A novel semiconductor photocatalytic reaction system employing a photo-emitting enzyme as an internal light source is pro-posed in the present study. The system completely overturns common sense that conventional photocatalytic reactions must require irradiation from an external light source. A horseradish peroxidase (HRP) catalyzing oxidative bioluminescence reaction of luminol in the presence of H₂O₂ and manganate nanosheets (MNSs) with a narrow bandgap were utilized for an internal light source and semiconductor photocatalysts, respectively, and both of them coexisted in a same reactant solution. In other words, nano-sized light sources were highly dispersed in the solution, resulting in photo-excitation of MNSs over the entire solution. Photo-activated MNSs simultaneously caused oxidation and reduction, where platinum hexachloride anions (PtCl₆^2-) were utilized as a model substance to be reacted photocatalytically. According to X-ray absorption near edge spectroscopy (XANES) of MNSs after the photocatalytic reaction, the anions were mainly transformed into solid phases of PtO₂ and/or Pt(OH)₄ by reacting with holes in MNSs. In contrast, a control experiment without HRP, i.e. a dark experiment, did not leave any evidence for photocatalytic reaction of PtCl₆^2-. The detailed mechanism and the advantages/disadvantages of the proposed unique system are explained.

KEYWORDS:

• Photocatalyst
• bioluminescence
• oxide nanosheet
• enzyme

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21870764.2023.2301239

Additional information

Funding

This work was supported by JSPS KAKENHI Grant Number 19K05407.