The P25 TiO 2 /4-chlorophenol photocatalytic system: Spectral sensitivity or lamp artefact?

Ti-Modified LaFeO3/β-SiC Alveolar Foams as Immobilized Dual Catalysts with Combined Photo-Fenton and Photocatalytic Activity

“…Given the impossibility of determining all the reaction intermediates and, hence, of knowing the number of holes consumed in the oxidation reactions at any reaction time, the time needed for total mineralization was extrapolated in the cases where total mineralization ([TOC]= 0) was not achieved within the test duration, considering that the TOC disappearance rate follows zero-order kinetics and should therefore be independent of [TOC] throughout the reaction. The obtained efficiencies for pure photocatalytic reactions using Ti-LFO/β-SiC foams are in the range of previously reported values for 4-CP mineralization,62,63 with photonic efficiencies for degradation and mineralization of 4-CP of about 0.2% and 1%, respectively 39,57. By contrast, the photonic efficiency for 4-CP degradation strongly increases with the dual photo-CWPO/photocatalysis process, up to 9.38% and 4.95% for the SG-LFO/β-SiC and the P25-LFO/β-SiC foam catalysts, respectively.…”

Qualitative Approaches Towards Useful Photocatalytic Materials

“…Ignoring the sharp emission lines of the light source, the estimation of quantum efficiencies gives rise to an erratic curve consisting of peaks and troughs, which lead to misleading conclusions over the spectral sensitivity of the sample. Adapted with permission from Lee et al ( 2017a ). ( C ) Modified action spectra plots of commercial carbon-modified TiO 2 (Kronos VLP 7,000, blue line) and Evonik P25 (orange line) during photodegradation of stearic acid, highlighting the impact of a photosensitized process driven by surface carbonaceous species.…”

“…Early studies observed an erratic trend of peaks and troughs in the action spectrum of TiO 2 during photodegradation of 4-chlorophenol (Emeline et al, 2000 ), which led to drawing conclusions about the spectral sensitivity of the catalyst. Recently, however, careful action spectrum studies (Lee et al, 2017a ) revealed that the work had neglected the emission lines of mercury from the Xe/Hg lamp used in the original experiments ( Figure 4B ). Similarly, the action spectrum of a carbon-modified TiO 2 commercial product ( Kronos VLP 700 ) (Orth-Gerber and Kisch, 2005 ) showed a trend ( Figure 4C ) inconsistent with the absorption spectrum of the pristine material (Quesada-Cabrera et al, 2014a ).…”