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August 4, 2026 September 9, 2026

Enhancement of TiO2 photocatalytic activity by structuring the photocatalyst film as photonic sponge - Notes

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Journal article

E. Carbonell, F. Ramiro-Manzano, I. Rodriguez, A. Corma, F. Meseguer and H. Garcia

Photochem. Photobiol. Sci. Volume 7 931-935 2008

Published abstract

A TiO2 film having "photonic sponge" architecture (ps-TiO2) has been prepared using titania Degussa P25 nanoparticles that have been infiltrated into a template obtained through the arrangement of a mixture of different size latex spheres. The resulting photonic sponge exhibits 3.3 fold higher initial photocatalytic degradation rate for succinonitrile disappearance than analogous films of the same thickness made of unstructured P25 TiO2 nanoparticles. When corrected for the three fold lower mass of the ps-TiO2 films with respect to more dense P25, the enhancement of the photocatalytic activity by the photonic sponge morphology for the same mass of photocatalyst is about one order of magnitude. It was also observed that films of photonic sponge of 3 micrometres depth are more efficient than thicker films (5 and 7 micrometres).

Figures

Complete Scheme 1 illustrating the preparation process for titanium dioxide photonic sponges
Scheme 1. Process for the preparation of photonic sponges.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

Complete Figure 1 cross-sectional SEM image of a titanium dioxide photonic sponge
Figure 1. Summary. SEM image of a cross section of a ps-TiO2 sample showing its porous structure.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

Complete two-panel Figure 2 with diffuse reflectance spectra of P25 and photonic sponge titanium dioxide films
Figure 2. Summary. Diffuse reflectance UV-Vis spectra of P25-3 and ps-TiO2-3 samples.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

Complete Figure 3 infrared spectrum of a photonic sponge film containing succinonitrile
Figure 3. Summary. IR spectrum of a ps-TiO2-5 film containing succinonitrile.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

Complete Figure 4 series of infrared spectra recorded during photocatalytic degradation
Figure 4. Summary. Series of IR spectra recorded at increasing irradiation times during succinonitrile photodegradation.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

Complete Figure 5 time-photodegradation curves for photonic sponge films of different thicknesses
Figure 5. Summary. Time-photodegradation plots for ps-TiO2 films as a function of film thickness.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

Complete Figure 6 time-photodegradation curves for unstructured P25 films of different thicknesses
Figure 6. Summary. Time-photodegradation plots for P25 films as a function of film thickness.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

Complete Scheme 2 comparing irradiation in thin and thick photocatalyst films
Scheme 2. Cross sections of thin and thick films illustrating inefficient irradiation when the film is too thick.

From E. Carbonell et al., Photochem. Photobiol. Sci. 7, 931-935 (2008), DOI 10.1039/B801954A. Reproduced by the authors under RSC author reuse rights.

How to cite

Article access and reuse

The published article is available from the Royal Society of Chemistry. RSC authors may reuse their own figures, diagrams, tables and images without a formal permission request when the material is fully acknowledged. The six figures and two schemes below were extracted as complete compositions from the local article PDF without enlargement.

Related publications

Connections within F. Ramiro-Manzano's publication record, selected from shared research topics and evidence reviewed in the source papers.

Complete original Figure 2 composition extracted directly from the article PDF
Journal article
J. Mater. Chem. 17, 3205-3209 (2007)
Solar energy harvesting in photoelectrochemical solar cells
I. Rodriguez, F. Ramiro-Manzano, P. Atienzar, J. M. Martinez, F. Meseguer, H. Garcia and A. Corma

What the related paper adds

This earlier paper establishes a scientific basis for Enhancement of TiO2 photocatalytic activity by structuring the photocatalyst film as photonic sponge. This paper compares the principal optical routes developed for titania photoelectrochemical cells instead of treating them separately. It places inverse opals and photonic sponges in the same device-level framework, shows broad photocurrent enhancement from the sponge architecture, and also tests corrugated metal electrodes as a route to improved charge collection.

What this paper adds to the related work

Building on the earlier contribution Solar energy harvesting in photoelectrochemical solar cells, this paper advances the research line. This study takes the photonic-sponge concept beyond photovoltaics and applies it directly to photocatalysis. Without changing the TiO2 chemistry, the multiscale void network increases photon residence near the absorption edge and produces a much larger degradation rate, revealing how physical architecture alone can raise catalytic efficiency.

Complete original Figure 2 composition extracted directly from the article PDF
Journal article
Chem. Commun., 242-244 (2007)
Apollony photonic sponge based photoelectrochemical solar cells
F. Ramiro-Manzano, P. Atienzar, I. Rodriguez, F. Meseguer, H. Garcia and A. Corma

What the related paper adds

This earlier paper establishes a scientific basis for Enhancement of TiO2 photocatalytic activity by structuring the photocatalyst film as photonic sponge. This work replaces the narrow spectral action of a periodic photonic crystal with a highly porous, quasi-fractal photonic sponge. Its interconnected cavities span several sizes, trap light across the near-ultraviolet and visible ranges, and turn broad-band scattering into a concrete strategy for improving dye-sensitized photoelectrochemical solar cells.

What this paper adds to the related work

Building on the earlier contribution Apollony photonic sponge based photoelectrochemical solar cells, this paper advances the research line. This study takes the photonic-sponge concept beyond photovoltaics and applies it directly to photocatalysis. Without changing the TiO2 chemistry, the multiscale void network increases photon residence near the absorption edge and produces a much larger degradation rate, revealing how physical architecture alone can raise catalytic efficiency.

SEM image of a titania inverse opal electrode with a 2 micrometre scale bar
Journal article
Photonics Nanostruct. Fundam. Appl. 3, 148-154 (2005)
Photonic crystals for applications in photoelectrochemical processes: Photoelectrochemical solar cells with inverse opal topology
I. Rodriguez, P. Atienzar, F. Ramiro-Manzano, F. Meseguer, A. Corma and H. Garcia

What the related paper adds

This earlier paper establishes a scientific basis for Enhancement of TiO2 photocatalytic activity by structuring the photocatalyst film as photonic sponge. This paper establishes inverse-opal metal-oxide architectures as optically monitorable materials for photochemistry. It follows template infiltration and removal through reflectance, extends the method across several oxides, and demonstrates that a titania inverse opal can improve a photoelectrochemical solar cell by controlling photon propagation inside the active material.

What this paper adds to the related work

Building on the earlier contribution Photonic crystals for applications in photoelectrochemical processes: Photoelectrochemical solar cells with inverse opal topology, this paper advances the research line. This study takes the photonic-sponge concept beyond photovoltaics and applies it directly to photocatalysis. Without changing the TiO2 chemistry, the multiscale void network increases photon residence near the absorption edge and produces a much larger degradation rate, revealing how physical architecture alone can raise catalytic efficiency.

Research fields

Bottom-up

TiO₂ nanoparticles are assembled into a disordered hierarchical photonic sponge whose voids span the wavelength scale, while reference films use the same photocatalyst in a compact morphology. The comparison isolates structural light management from chemical composition.

Characterization

Cross-sectional SEM, optical absorbance and time-resolved infrared monitoring of succinonitrile degradation measure morphology, photon capture and catalytic outcome. Normalising for the lower TiO₂ mass shows that stronger activity follows enhanced absorption near the semiconductor edge.

RESEARCH TOPICS

HarvestingThe porous architecture improves how incident photons are used rather than changing the TiO₂ chemistry. For films of equal thickness, the photonic sponge accelerates succinonitrile degradation by a factor of 3.3; after correcting for its three-times lower TiO₂ mass, the intrinsic activity enhancement is about one order of magnitude.InterferenceThe mixture of latex-sphere sizes creates a disordered network of voids from roughly 200 to 2000 nm, broadening the range of optical paths instead of producing one narrow photonic stop band. Figure 2 shows the strongest absorbance gain near the TiO₂ absorption edge above 380 nm, where multiple scattering keeps weakly absorbed photons inside the catalyst for longer.MaterialsDegussa P25 nanoparticles - approximately 80% anatase and 20% rutile - are packed around a sacrificial blend of latex spheres. Because the comparison samples use the same P25 material and processing, the measured activity difference can be assigned to morphology and photon transport rather than to a different semiconductor composition.ChemistryPhotocatalysis is followed through the disappearance of succinonitrile deposited on the films and irradiated with a medium-pressure mercury lamp above 300 nm. The porous sponge increases the reaction rate without metal or non-metal doping: the chemical gain comes from stronger absorption on the red side of the TiO₂ onset and from making more of the nanoparticle surface optically active.
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