Unique Photocatalytic Activity Research Articles

Copper and nitrogen-doped carbon quantum dots as green nano-probes for fluorimetric determination of delafloxacin; characterization and applications

BackgroundCarbon quantum dots (CQDs) have gained much interest recently for being efficient probes. Their cost-effectiveness, eco-friendliness, and unique photocatalytic activities made them distinctive alternatives to other luminescent approaches like fluorescent dyes and luminous derivatization. Meanwhile, delafloxacin (DLF) is a recently approved antibacterial medicine. DLF has been authorized for the treatment of soft-tissue and skin infections as well as pneumonia. Therefore, new eco-friendly, cost-effective, and sensitive tools are needed its estimation in different matrices. ResultsIn the proposed study, green copper and nitrogen carbon dots (Cu-N@CDs) were synthesized from a green source (plum juice with copper sulphate). Cu-N@CQDs were then characterized using multiple tools including X-ray photon spectroscopy (XPS), FTIR and UV-VIS spectroscopy, Zeta potential measurements, High-resolution transmission electron microscopy (HRTEM), and fluorescence spectroscopy. After gradually adding DLF, the developed quantum dots’ fluorescence was significantly enhanced within the working range of 0.5–100.0 ng mL−1. The limits of detection and quantification were 0.08 and 0.27 ng mL−1, respectively. The accuracy of the proposed method ranged from 96.00 to 99.12 % in recovery%, when recovered from milk and plasma samples. SignificanceCu-N@CDs were utilized and validated for selectively determining DLF in several matrices including pharmaceutical forms, human plasma and in milk samples using spectrofluorimetric technique. The bio-analytical method is simple and could be used in content uniformity testing as well as in therapeutic drug monitoring in human plasma.

Antibacterial Properties and Application of Bi2Sn2O7/ZnO Composite Photocatalytic Materials.

In this experiment, Bi2Sn2O7/ZnO composite photocatalytic materials were synthesized by a hydrothermal method and characterized by XRD, SEM, and EDS, etc. The prepared Bi2Sn2O7/ZnO has a nanorod structure and high phase purity. The photocatalytic antimicrobial performance of Bi2Sn2O7/ZnO against bacteria and fungi under visible light was significantly better than that of single Bi2Sn2O7 and ZnO. In particular, 1000 mg/L 1 : 3 Bi2Sn2O7/ZnO showed an antimicrobial rate of more than 97 % against Escherichia coli, Staphylococcus aureus, and Candida albicans, which are widely present in the nature. The free radical trapping experiments were selected and the antimicrobial mechanism was investigated, and the results showed that the antimicrobial process of the Bi2Sn2O7/ZnO system was regulated by the free radicals such as ⋅OH, h+, and e-, which were generated by its unique photocatalytic activity. Finally, MTT cytotoxicity experiments demonstrated that the Bi₂Sn₂O₇/ZnO composite was not toxic to cells. In addition, the antimicrobial performance of Bi2Sn2O7/ZnO on real livestock wastewater and the real-life application of the prepared Bi2Sn2O7/ZnO PCL composite antibiotic film for antimicrobial treatment of freshly cut fruits' surfaces under visible light were experimentally investigated. This study provides a new idea for Bi2Sn2O7/ZnO as a photocatalytic antimicrobial agent.

Photocatalytic Aptamer Chemiluminescent System for a Homogeneous, Reliable, Label-Free, Generic Assay of Small Molecules.

Chemiluminescence is a powerful analytical technique with many advantages, while aptamers are well-known as good molecular recognition units. However, many aptamer-based chemiluminescence assays employed interface sensing, which often needed several immobilization, separation, and washing steps. To minimize the risks of contamination and false-positive, we for the first time proposed a photocatalytic aptamer chemiluminescent system for a homogeneous, label-free, generic assay of small molecules. After binding to a DNA aptamer, thioflavin T has a unique photocatalytic oxidase activity to activate the system's luminol chemiluminescence. Then, the specific binding between the aptamer and target molecules will compete with the above process. Therefore, we can realize the efficient assay of different analytes including estradiol and adenosine. Such a homogeneous chemiluminescent system allowed a direct assay of small molecules with limits of detection in a nM level. Several control tests were carried out to avoid possible false-positive results, which were originated from the interactions between analytes and sensing interfaces previously. This homogeneous chemiluminescent system provides a useful strategy to reliably assay various analytes in the pharmacy or biology field.

A review on biological synthesis of ZnO nanostructures and its application in photocatalysis mediated dye degradation: An overview.

Zinc oxide (ZnO) has several industrial applications due to its versatile properties, which lead to its continuously increasing demand in different industrial sectors. Additionally, ZnO nanostructures possess unique photocatalytic activity, and because of this, they are being applied to degrade organic dyes through photocatalysis for wastewater treatment. Nevertheless, chemical synthesis methods to develop ZnO nanostructures have raised concerns related to environmental issues, furthermore, these methods are found to be costly and tedious. As a result, the synthesis of ZnO nanostructures using green methods is gaining popularity due to its low cost and eco-friendly mode, while avoiding the use of toxic chemicals. Green synthesis of ZnO nanostructures using different biological approaches involving plants, algae, and different microorganism-derived bioactive compounds has been well reported for diverse applications. Among different applications, ZnO nanostructures that enable photocatalysis to degrade dye have been found to be imperative for wastewater treatments. Therefore, the current review explores recent studies on green synthesis approaches to prepare ZnO nanostructures via adopting different biological methods that rely on plants, algae, and bacterial microorganisms. The properties of ZnO nanostructures, along with their green synthesis routes and feasible mechanisms, have also been discussed in this review. This review focuses on the use and efficiency of green route synthesized ZnO nanostructures as nanophotocatalysts for the degradation of organic dyes in wastewater treatment. Additionally, existing challenges in green synthesis methods and the efficiency of ZnO nanostructures to degrade organic dyes following photocatalysis has been discussed.

Framework Ti-rich titanium silicalite-1 zeolite nanoplates for enhanced photocatalytic H2 production from CH3OH

As a successful industrial catalyst, titanium silicalite-1 zeolite (TS-1) also possesses unique photocatalytic activity, but still challenging due to the unsatisfactory activity and unclear photocatalytic mechanism. Here, we achieved the optimization of TS-1 in both the morphology and content of framework Ti by a facile dual-structure directing agent method. The Ti-rich TS-1 nanoplates exhibit enhanced photocatalytic H2 production performance from methanol. The structure-activity relationship was revealed that the nanoplate-like morphology is beneficial to the photocatalytic activity, owing to the largely retainment of photogenerated electrons. Combined with in-situ DRIFTS and theoretical calculations, it is proposed that Ti−O group would function as a whole to serve as the active site, rather than separated Ti and O sites for reduction and oxidation half reactions respectively. The formation of hydroxylated Ti can also promote the photocatalytic performance. These insights into the mechanisms suggest the great potential of Ti-rich TS-1 nanoplates as commercial photocatalytic materials.

Silver-decorated black phosphorus: a synergistic antibacterial strategy

Black phosphorus (BP) exhibits great potential as antibacterial materials due to its unique photocatalytic activity. However, the unsatisfactory optical absorption and quick recombination of photoinduced electron–hole pairs restrain its photocatalytic antibacterial performance. In this work, silver nanoparticles (AgNPs) were decorated on BP to construct BP@AgNPs nanohybrids and then introduced into poly-l-lactic acid scaffold. Combining the tunable bandgap of BP and the LSPR effect of AgNPs, BP@AgNPs nanohybrids displayed the broaden visible light absorption. Furthermore, AgNPs acted as electron acceptors could accelerate charge transfer and suppress electron–hole recombination. Therefore, BP@AgNPs nanohybrids achieved synergistically enhanced photocatalytic antibacterial activity under visible light irradiation. Fluorescence probe experiment verified that BP@AgNPs promoted the generation of reactive oxygen species, which could disrupt bacteria membrane, damage DNA and oxide proteins, and finally lead to bacteria apoptosis. As a result, the scaffold possessed strong antibacterial efficiency with a bactericidal rate of 97% under light irradiation. Moreover, the scaffold also exhibited good cytocompatibility. This work highlighted a new strategy to develop photocatalytic antibacterial scaffold for bone implant application.

Molecular design of dye-TiO2 assemblies for green light-induced photocatalytic selective aerobic oxidation of amines

Dye-semiconductor assemblies are very versatile visible light photocatalysts in terms of tunability by tweaking either dye molecules or semiconductor materials. Here, we adopted a strategy of molecular inverse design of alizarin red S (ARS) to identify the blueprint underlying the superior photocatalytic activity of ARS-TiO2 assembly. We discovered that the substituted –OH groups of anthraquinone provide visible light absorption and binding sites. Importantly, the molecular features of 1,2-dihydroxyanthraquinone (1,2-DHA) contributes mostly to the unique photocatalytic activity after binding with TiO2 with broad visible light absorption which can be maintained at high concentration of amines. Moreover, the electron-withdrawing effect of -SO3−Na+ groups increase the acidities of substituted –OH groups, leading to stronger binding and subsequent higher activity. Ultimately, in situ formed 1,2-DHA-TiO2 assembly can be a powerful photocatalyst for green light-induced selective oxidation of amines into imines with aerial O2. This work makes evident the promise of molecular design in tailoring dye-semiconductor assemblies for visible light-induced photocatalytic selective chemical transformations.

Polyurethane nanofibrous membranes decorated with reduced graphene oxide–TiO2 for photocatalytic templates in water purification

We hereby report a reduced graphene oxide–titanium dioxide (rGO–TiO2)-loaded polyurethane (PU) nanofibrous membrane having visible-light-responsive photocatalytic activity and antifouling property. The functionality is significantly augmented by the hybridization of rGO–TiO2 with nanofibrous membrane. This results in a synergistic combination of high surface area of nanofiber and unique photocatalytic activity of rGO–TiO2. 10 wt% rGO–TiO2-loaded membrane showed an average fiber diameter of 271.83 ± 11.38 nm. Both the thermal stability and mechanical stability of the membrane increase after rGO–TiO2 loading. The optimized PU/10rGO–TiO2 membrane exhibited a water flux of 12810 ± 49.65 Lm−2 h−1, oil rejection of 85.50%, and flux recovery ratio of 88.10%. Theoretical evaluation of fouling model suggests that all the membranes follow cake filtration model. The photocatalytic activity of nanofibrous membrane increases with an increase in rGO–TiO2 concentration in the membrane, and PU/10rGO–TiO2 nanofibrous membrane showed 95% of degradation against methylene blue dye. Thus, the prepared membrane can be suggested for an ideal candidate for antifouling and photocatalytic templates in water filtration systems.

Serendipitous Assembly of Mixed Phase BiVO4 on B-Doped g-C3N4: An Appropriate p-n Heterojunction for Photocatalytic O2 evolution and Cr(VI) reduction.

Type II p-n heterojunction B-doped g-C3N4/BiVO4 moieties have been fabricated by depositing n-type BiVO4 on the surface of p-type 1 wt % B-doped g-C3N4 for the first time. The materials were characterized by PXRD, XPS, UV-vis DRS, IR, PL, and Raman analysis. The photocatalytic activities of as synthesized samples were studied toward reduction of Cr(VI) and water splitting reaction to generate oxygen. The results reveal that Type II p-n heterojunction considerably enhance the photocatalytic activity as compared to neat n-type BiVO4 and p-type B-doped g-C3N4. 50% BiVO4/B-doped g-C3N4 heterostructure exhibited the best photocatalytic activity, which is 7.9-fold higher than that of BiVO4 and followed by a pseudo first order kinetics with apparent first order rate constant of 0.063 min-1. Again the heterojunction is able to produce 4.2 times higher oxygen evolution value as related to pristine BiVO4. The superior photocatalytic activity is attributed to higher visible light utilization and lower recombination of electron-hole pairs by creating a p-n junction. PXRD and HRTEM data suggest the formation of mixed phase monoclinic and tetragonal BiVO4 thereby creating a heterojunction for the improvement of the photocatalytic performances. The formation of mixed-phase BiVO4 is attributed to the high temperature calcination as well as surface energy of B-doped g-C3N4. The oxygen vacancy in the system is confirmed through XPS and Raman analysis. Moreover, the excellent photocurrent response by the designed photocatalyst at lower overpotential and decrease in carrier recombination as compared to bulk one, studied from LSV and electrochemical impedance spectroscopy, validate the unique photocatalytic activity of the catalyst. The formation of the p-n heterojunction is confirmed from a Mott-Schottky analysis. The work shed new light on the assembly of the p-n heterojunction, showing excellent photocatalytic properties in a simple way.

Unique photocatalytic activities of transition metal phosphide for hydrogen evolution

Economical, efficient and stable single photo-catalysts are vital for realizing enhanced photo-catalytic H2 evolution activity. In this study, we report two n-type single transition metal phosphide with excellent photo-catalytic activity under visible light irradiation, which is of great significance for the discovery and synthesis of novel and more efficient photo-catalysts. And completely controllable synthesis will greatly reduce application costs. Furthermore, the fairly high activity of H2 evolution of the resulting catalysts having low crystallinity and extremely strong optical properties is reveled in detail via investigating the dynamics of hydrogen generation of CoP and WP. Moreover, it is found that CoP and WP have low band-gap energy and increased optical absorption properties through studies. Meanwhile, low crystallinity state for they also is get by XRD technology. These may be the main reasons why CoP and WP exhibit efficient H2 evolution activity. In addition, the possible mechanism showing high photo-catalytic activity of hydrogen evolution for CoP and WP is proposed by a series of other characterizations, such as SEM, TEM, XPS, BET, transient photo-current response, steady-state fluorescence, transient-state fluorescence and Mott-Schottky studies etc.

Thermally oxidized CdS as a photoactive material

CdS oxidized in wide temperature range shows unique photocatalytic activity both in UV and visible light.

Study on the antimicrobial mechanism of Ag/ZnO coating

Study on the antimicrobial of Ag/ZnO coating already become one of the research focuses in Antibacterial material business, which Ag and ZnO have Efficient, broad spectrum, safe, green antibacterial properties. But at present, different scholars have different views and understanding on the antibacterial properties and antibacterial mechanism of the antimicrobial of Ag/ZnO coating. In this paper, the recent research progress of antibacterial properties and antibacterial mechanism of the antimicrobial of Ag/ZnO coating at home and abroad in recent years were reviewed. In this paper, the antibacterial mechanism of the antimicrobial of Ag/ZnO coating was elaborated in detail from 4 aspects: the destruction of the integrity of bacterial cells, the blocking of bacterial ATP and DNA replication, the generation of reactive oxygen species and the unique photocatalytic antibacterial activity of ZnO. The author points out that the antimicrobial process of the antimicrobial of Ag/ZnO coating is affected by various mechanisms. It is concluded that the antibacterial process of the antimicrobial of Ag/ZnO coating is more complicated, study the mode of action of deeper Ag and ZnO antibacterial and antibacterial mechanism and the influential factors will be helpful to widely used the antimicrobial of Ag/ZnO coating. Key words: Antibacterial material; Silver bearing Zinc Oxide; Antibacterial property; Antibacterial mechanism

Bioinspired Mesoporous Chiral Nematic Graphitic Carbon Nitride Photocatalysts modulated by Polarized Light.

Endowing materials with chirality and exploring the responses of the material under circularly polarized light (CPL) can enable further insight into the physical and chemical properties of the semiconductors to be gained, thus expanding on optoelectronic applications. Herein a bioinspired mesoporous chiral nematic graphitic carbon nitride (g-C3 N4 ) for efficient hydrogen evolution with polarized light modulation based on chiral nematic cellulose nanocrystal films prepared through silica templating is described. The mesoporous nematic chiral g-C3 N4 exhibits an ultrahigh hydrogen evolution rate of 219.9 μmol h-1 (for 20 mg catalyst), corresponding to a high enhancement factor of 55 when compared to the bulk g-C3 N4 under λ>420 nm irradiation. Furthermore, the chiral g-C3 N4 material exhibits unique photocatalytic activity modulated by CPL within the absorption region. This CPL-assisted photocatalytic regulation strategy holds great promise for a wide range of applications including optical devices, asymmetric photocatalysis, and chiral recognition/separation.

Construction of Plasmonic Ag and Nitrogen-Doped Graphene Quantum Dots Codecorated Ultrathin Graphitic Carbon Nitride Nanosheet Composites with Enhanced Photocatalytic Activity: Full-Spectrum Response Ability and Mechanism Insight.

The full utilization of solar energy has attracted great attention in the photocatalysis and environmental pollutant control. In this study, the local surface plasmon resonance effect of Ag nanoparticles (Ag NPs) with the upconversion property of nitrogen-doped graphene quantum dots (N-GQDs) was first combined for the formation of ternary Ag/N-GQDs/g-C3N4 nanocomposites. The prepared material presents enhanced full-spectrum light response ability, even in near-infrared (NIR) light. The experiment results disclosed that the 0.5% N-GQDs and 2.0% Ag NPs co-doped g-C3N4 show the highest photocatalytic activity, achieving 92.8 and 31.3% removal efficiency under full-spectrum light and NIR light irradiation, respectively, which was three-fold than that of pristine g-C3N4. The boosted photocatalytic activity can be attributed to the synergistic effect among the g-C3N4, N-GQDs, and Ag NPs. The g-C3N4 nanosheets can serve as the reaction matrix and support for the dispersion of N-GQDs and Ag NPs, inhibiting their agglomeration. The existence of Ag NPs and N-GQDs can promote the light absorption and transfer ability, leading to the generation of more photoinduced charges. Simultaneously, N-GQDs and Ag NPs can efficiently transfer and reserve electrons, which can accelerate the photoinduced electrons' migration, inhibiting the recombination. The comprehensive effect of the reasons mentioned above resulted in the unique photocatalytic activity of the prepared Ag/N-GQDs/g-C3N4 nanocomposites. This study provides a new strategy for the formation of highly efficient photocatalysts with broad-spectrum light response ability and the potential for realistic wastewater pollution control.

Hydrothermal synthesis of novel heterostructured Fe2O3/Bi2S3 nanorods with enhanced photocatalytic activity under visible light

The development of efficient visible-light photocatalyst heterostructures remains a major concern for obtaining desirable material properties and effective carrier transformation. Here, we demonstrate, for the first time, the synthesis of novel heterostructures of Fe2O3/Bi2S3 nanorods via a one-step hydrothermal route and employed effectively as visible-light-driven photocatalysts for the degradation of organic pollutants of methylene blue dye (MB) and phenol. TEM and FE-SEM images displayed that Fe2O3/Bi2S3 heterostructure is nanorods with ∼30–60nm diameter and 0.5–1μm length. The newly prepared Fe2O3/Bi2S3 nanorods exhibit greatly enhanced photocatalytic activity toward both MB and phenol compared to pure Bi2S3 and the heterostructure with low molar ratio of 0.06 Fe2O3/Bi2S3 exhibits the best photocatalytic activity under visible light irradiation. A maximum degradation efficiency of MB and phenol ∼90% and 96% was accomplished using Fe2O3/Bi2S3 nanorods compared to only 60% and 69% using pure Bi2S3, respectively. The photodegradation rates for MB and phenol are promoted respectively as ∼2.6 and 3 times using Fe2O3/Bi2S3 heterostructure higher than pure Bi2S3. Photoluminescence spectra measurement along with the calculation of relative band alignment indicated that Fe2O3/Bi2S3 heterostructure significantly suppress the recombination of photogenerated charge carriers, which is beneficial to improve the photocatalytic activity. The facile synthesis approach, unique photocatalytic activity and excellent reusability of the current Fe2O3 modified Bi2S3 nanostructure make it a promising photocatalyst for the environmental remediation related fields.

Modulating the Photocatalytic Activity of Graphene Quantum Dots via Atomic Tailoring for Highly Enhanced Photocatalysis under Visible Light

Precise control over doping of photocatalysts is required to modulate their photocatalytic activity in visible light‐driven reactions. Here, a single precursor‐employing bottom‐up approach is developed to produce different heteroatom‐doped graphene quantum dots (GQDs) with unique photocatalytic activities. The solvothermal reaction of a norepinephrine precursor with redox active and condensable moieties effectively produces both nitrogen/sulfur codoped GQDs (NS‐GQDs) and nitrogen‐doped GQDs (N‐GQDs) by simply varying solvents (from dimethyl sulfoxide to water) under microwave irradiation. As‐prepared NS‐GQDs and N‐GQDs show similar lateral sizes (3–4 nm) and heights (1–2 nm), but they include different dopant types and doping constitution and content, which lead to changes in photocatalytic activity in aerobic oxidative coupling reactions of various amines. NS‐GQDs exhibit much higher photocatalytic activity in reactions under visible light than N‐GQDs and oxygen‐doped GQDs (O‐GQDs). The mechanism responsible for the outstanding photocatalytic activity of NS‐GQDs in visible light‐driven oxidative coupling reactions of amines is also fully investigated.

Tuning photo-catalytic activities of TiO2 nanoparticles using dimethacrylate resins

ObjectiveThe unique photo-catalytic activities (PCAs) of titanium dioxide nanoparticles (TiO2 NPs) made them attractive in many potential applications in medical devices. The objective of this study is to optimize the benefits of PCAs of TiO2 NPs through varying chemical structures of dimethacrylate resins. MethodsTiO2 NPs were functionalized to improve the PCAs and bonding to the resins. The PCAs of TiO2 NPs were evaluated using electron paramagnetic resonance (EPR) and UV–vis spectroscopy to determine the amount of the radicals generated and the energy required for their production, respectively. The beneficial effects of the radicals were assessed through: (1) the improvement of degree of vinyl conversion (DC) and (2) modification of resin hydrophilicity. One-way ANOVA with a 95% confidence interval was used to indicate the significant differences between the experimental groups. ResultsEPR and UV–vis results clearly showed that the functionalization of TiO2 NPs enhanced PCAs in terms of generating radicals under visible light irradiation. The presence of hydroxyl and carboxylic acid functionalities played an important role in DC enhancement and hydrophilicity modification. The DC could be increased up to 22% by adding only 0.1wt% TiO2 NPs. Viscosity of the resins had minimal or no role in DC improvement through TiO2 NPs. In resins with abundant hydroxyl groups, radicals were more effective in making the resin more hydrophilic. SignificanceKnowledge learned from this study will help formulating nano-composites with optimized use of TiO2 PCAs as co-initiators for photo-polymerization, additives for making super-hydrophilic materials and/or antibacterial agents.

Nitrogen-doped titanium oxide microrods decorated with titanium oxide nanosheets for visible light photocatalysis

Nitrogen-doped titania with a unique two-level hierarchical structure and visible light photocatalytic activity is reported. Thus, nitrogen-doped titanium oxide microrods decorated with N-doped titanium oxide nanosheets were synthesized by a hydrothermal reaction in NH4OH and postcalcination. During the calcination, the in situ incorporation of nitrogen atoms of ammonium ion into titania lattice was accompanied by the structural evolution from titanate to anatase titania. The morphological and structural evolution was monitored by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Raman, Fourier transform infrared (FTIR), x-ray absorption near edge structure (XANES), x-ray photoelectron spectroscopy (XPS), and adsorption isotherms. The N-doping brought visible light absorption, and the material exhibited high photocatalytic activity in the decomposition of Orange II under visible light irradiation (λ ≥ 400 nm), especially when it was loaded with 1 wt% Pt as a cocatalyst.

Highly ordered mesoporous titania–zirconia photocatalyst for applications in degradation of rhodamine-B and hydrogen evolution

We report a facile synthesis of highly ordered mesoporous titania–zirconia composites with broad Ti/Zr ratios via an evaporation-induced self assembly (EISA) process. Amphiphilic poly(alkylene oxide) block copolymers, P123 and F127, serve as structure-directing agents (SDAs). By adjusting initial molar ratios of copolymer to metal precursors, titania–zirconia nanocomposites with controlled texture and composition are obtained in a wide range from 10 to 90 mol% TiO 2. Small-angle X-ray diffraction (SAXRD) and transmission electron microscopy (TEM) measurements reveal the two-dimensional (2D) hexagonal mesostructure ( p6 mm) with large-domain regularity. These mesostructured composites possess large surface areas and pore volumes, narrow pore size distributions, and abundant surface Lewis acid sites, resulting in unique photocatalytic activities for degradation of rhodamine-B and hydrogen evolution in methanol aqueous solution. Their good photocatalytic abilities are ascribed to the cooperative effect of the porosity and crystallinity.

Enhancement of the photocatalytic activity of TiO2through spatial structuring and particle size control: from subnanometric to submillimetric length scale

This review summarizes the physical approaches towards enhancement of the photocatalytic activity of titanium dioxide by controlling this semiconductor in a certain length scale from subnanometric to submillimetric distances and provides examples in which the photocatalytic activity of TiO2 is not promoted by doping or changes in the chemical composition, but rather by application of physical concepts and spatial structuring of the semiconductor. Thus, encapsulation inside the micropores and cavities of zeolites (about 1 nm) renders small titanium oxide clusters with harnessed photocatalytic activity. On the other hand, nanometric titanium particles can be ordered forming structured periodic mesoporous materials with high specific surface area and well defined porosity. Titiania nanotubes of micrometric length, either independent or forming a membrane, also exhibit unique photocatalytic activity as consequence of the long diffusion length of charge carriers along the nanotube axis. Finally, photonic crystals with an inverse opal structure and the even more powerful concept of photonic sponges can serve to slow down visible light photons inside the material, increasing the effective optical path in such a way that light absorption near the absorption onset of the material is enhanced considerably. All these physical-based approaches have shown their potential in enhancing the photocatalytic activity of titania, paving the way for a new generation of novel structured photocatalysts in which physical and chemical concepts are combined.