(a) Normalized red components (Rt)
of the resazurin dye upon irradiation time over the r-center sample.
(b) The corresponding percentages of surface anatase as determined
by the DFT fitting model are indicated and refer to the points labeled
(A–E). (b) The compositions are estimated by the DFT fitting
model and by Raman analysis for a linear cross-section of the r-center
film, which is indicated by the dotted line in (c). (c) Photographic
images of the dye-coated r-center film after exposure to UV irradiation
showing the slower transformation of the resazurin dye in the rutile-rich
center. Irradiation time in seconds is indicated for each photograph.
(d) Variation of local formal quantum efficiencies, ξ (units,
photon–1), defined here as the Rz photoreduction rate of per incident photon, with the
local phase fraction of anatase predicted by the DFT-simulated fitting
model. The ξ values are plotted on a log scale. Color mapping
of the points is based on the anatase:rutile ratio.