Boosting visible light harvesting and charge separation in surface modified TiO₂ photonic crystal catalysts with CoO_x nanoclusters

Abstract

Photonic crystal structuring has emerged as a promising approach to improve the utilization of solar energy by metal oxide semiconductor photocatalysts based on the combination of slow-light, pore interconnectivity and...

Graphene Quantum Dot-TiO2 Photonic Crystal Films for Photocatalytic Applications

“…It should be noted that although the obtained values provide only a rough estimate based on modified Bragg’s law, they agree with those obtained by rigorous theoretical simulations of R% spectra for TiO 2 PCs [ 16 ]. Moreover, the observed increase of the filling fraction for the smaller macropores complies favorably with recent results on co-assembled TiO 2 PC films [ 13 ]. In that case, an analogous increase of surface area and mesopore volume was detected, related to the enhanced mesoporosity of the inverse opal skeletal walls due to the increase of available interfaces for the smaller macropores [ 50 ].…”

“…The formation of ca. 8 nm anatase nanoparticles can be accordingly predicted from the frequency vs. width correlation curves of the E g mode [54], in agreement with recent results on the formation of sub-10 nm anatase nanocrystals in co-assembled TiO 2 inverse opals using the TiBALDH precursor [13,15]. Furthermore, no Raman mode such as the G band arising from the stretching of sp 2 carbon atoms and the highly dispersive D-band activated by defects [15,16,40], could be traced for the GQD-PC films in the frequency range of 1000-2000 cm −1 .…”

“…More importantly, GQDs deposition resulted invariably in the improvement of both reaction rates and , most pronounced under visible light ( λ > 400 nm), where the films VLA performance is compromised by the inherently weak electronic absorbance of both anatase PC and mixed-phase P25 films [ 13 ]. Under UV–VIS illumination, a clear maximum of was observed for both pristine and QGD-PC211 films ( Figure 7 d), followed by the corresponding pristine and modified PC261.…”

“…The obtained reaction rates varied significantly depending on the macropore diameter of the inverse opals and the illumination conditions, as shown in Figures 7d and 8d, indicative of considerable differences in the light-harvesting ability of the PC films. More importantly, GQDs deposition resulted invariably in the improvement of both reaction rates r Vis and r UV−Vis , most pronounced under visible light (λ > 400 nm), where the films VLA performance is compromised by the inherently weak electronic absorbance of both anatase PC and mixed-phase P25 films [13]. Under UV-VIS illumination, a clear maximum of r UV−Vis was observed for both pristine and QGD-PC211 films (Figure 7d), followed by the corresponding pristine and modified PC261.…”

“…Significant efforts have been accordingly devoted to combine these distinctive structural features with competent compositional modifications of the materials properties such as heterostructuring with noble metal nanoparticles [ 7 , 8 , 9 , 10 ], metal oxide nanoclusters [ 11 , 12 , 13 ], and graphene oxide nanosheets [ 14 , 15 , 16 ] in order to amplify photocatalytic performance for environmental remediation and solar energy conversion applications. Among the diverse TiO 2 heterojunction photocatalysts, interfacial coupling of titania with graphene and its derivatives has been an effective method to enhance charge separation and visible light harvesting based on graphene materials’ electron acceptor action and charge transport along with its broadband light absorption [ 17 , 18 , 19 ].…”