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Phenomenological Rule from Correlations of Conduction/Valence Band Energies and Bandgap Energies in Semiconductor Photocatalysts: Calcium Bismuthates versus Strontium Bismuthates
Author(s) -
Shtarev D. S.,
Ryabchuk V. K.,
Rudakova A. V.,
Shtareva A. V.,
Molokeev M. S.,
Kirichenko E. A.,
Serpone N.
Publication year - 2020
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201902236
Subject(s) - strontium , electronegativity , band gap , x ray photoelectron spectroscopy , valence (chemistry) , chemistry , alkaline earth metal , metal , analytical chemistry (journal) , hamiltonian (control theory) , semiconductor , atomic physics , materials science , condensed matter physics , nuclear magnetic resonance , physics , optoelectronics , mathematical optimization , mathematics , organic chemistry , chromatography
A number of calcium bismuthates were synthesized (25 to 50 mol% in Ca) and characterized by XRD, SEM, EDX, XPS and DRS techniques; the latter provided an estimate of the bandgap energies (E bg =2.41 to 3.29 eV) via Tauc plots for indirect transitions, whereas XPS established the potentials (vs NHE) of their respective valence bands (and thus the conduction bands). Linear correlations existed between E VB /E CB and E bg that when compared with those of strontium bismuthates (reported earlier) showed that differences in energies at E bg =0 eV are related to the difference in the absolute electronegativities of Ca and Sr, from which the following empirical phenomenological rule is postulated: replacing one alkaline earth metal in bismuthates by another causes the points of intersection of the linear correlations E CB (E bg ) and E VB (E bg ) to be displaced by an amount equal to twice the difference in absolute electronegativities of these metals.