Issue 8, 2016

Ferroelastic domains improve photochemical reactivity: a comparative study of monoclinic and tetragonal (Bi1−0.5xNa0.5x)(V1−xMox)O4 ceramics

Abstract

The relative reactivities of monoclinic and tetragonal BiVO4-based ceramics are described, focusing on the contributions of ferroelastic domains and surface orientations. First, the photo-oxidation of Mn2+ on monoclinic BiVO4 is shown to be domain selective, occurring on the set of domains that is not active for the photo-reduction of Ag+. Next, the domain and orientation dependent photochemical reduction of Ag+ is investigated for two samples in the co-doped family (Bi1−0.5xNa0.5x)(V1−xMox)O4: a monoclinic sample (x = 0.05) and a tetragonal sample (x = 0.175). Like BiVO4, the x = 0.05 sample has ferroelastic domains that exhibit contrast in piezoresponse force microscopy (PFM) and exhibit domain specific reactivity. The x = 0.175 sample has no domains, no PFM contrast, and uniform grain reactivity. The orientation dependence of Ag+ reduction is similar for the two samples, with surfaces near (001) being more active than others. For any given orientation, however, the monoclinic sample is quantitatively more active than the same orientation in the tetragonal sample. These collected results are consistent with the hypothesis that monoclinic-structured BiVO4 ceramics have enhanced photochemical activity owing to ferroelastic domain-selective reactivity, which allows for local separation of photogenerated carriers and redox reactions.

Graphical abstract: Ferroelastic domains improve photochemical reactivity: a comparative study of monoclinic and tetragonal (Bi1−0.5xNa0.5x)(V1−xMox)O4 ceramics

Supplementary files

Article information

Article type
Paper
Submitted
20 Jul 2015
Accepted
31 Jul 2015
First published
12 Aug 2015

J. Mater. Chem. A, 2016,4, 2951-2959

Author version available

Ferroelastic domains improve photochemical reactivity: a comparative study of monoclinic and tetragonal (Bi1−0.5xNa0.5x)(V1−xMox)O4 ceramics

R. Munprom, P. A. Salvador and G. S. Rohrer, J. Mater. Chem. A, 2016, 4, 2951 DOI: 10.1039/C5TA05551B

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