Nanoporous Metal Oxide Research Articles

Zeolite Crystallization Inside Chemically Recyclable Ordered Nanoporous Co3O4 Scaffold: Precise Replication and Accelerated Crystallization.

The synthesis of mesoporous zeolites has garnered attention with regard to improving their catalytic and adsorption performances. While the hard-templating method provides opportunities to design precisely controlled hierarchical micro- and mesoporous structures, synthesizing mesoporous zeolites without external precipitation requires significant work. This is mainly due to the absence of usable templates other than carbon with hydrophobic surfaces. Herein, it is demonstrated that the Co3O4 template is valuable in preparing mesoporous silicalite-1 and ZSM-5 with a precisely controlled porous structure through hydrothermal synthesis. Unlike conventional carbon templates, the Co3O4 template is relatively hydrophilic, effective in suppressing external precipitation, and is reusable by dissolving in an acidic solution. The crystallization process also differs from that of the carbon template, as the silicate precipitates on a 3D ordered nanoporous Co3O4 scaffold, followed by crystallization and crystal growth. Furthermore, it is unexpectedly observed that the zeolite crystallization is accelerated in the Co3O4 template. The synthetic approach utilizing nanoporous metal oxides opens new doors for the control of the hierarchical structure of zeolites, as well as for the design of metal oxide-zeolite nanocomposite catalysts, due to the potential extensibility of the combination of metal oxides and zeolites.

Three-dimensional MOFs confined Anderson-type POMs clusters—Templated fabrication of porous Co-NiMo/Cr2O3 catalyst with superior NH3-SCR catalytic activity

Fabricating ecofriendly and high-performance NOx reduction catalysts is significant but challenging. This study introduces an innovative approach for creating homogeneous and porous Co-NiMo/Cr2O3 composites by employing a POMs@MOFs (POMs = polyoxometalates, MOFs = metal organic frameworks) core − shell template as a precursor and subsequent high-temperature treatment, in which the Anderson-type POMs are confined within the MIL-101 MOFs as secondary building units. The well-organized architecture of NiMo6@MIL-101 made it possible to provide a widely dispersed metal source and later transform into defect-rich catalyst. This confinement strategy allows the prepared Co-NiMo/Cr2O3 catalysts to be uniformly dispersed without aggregation and exposes abundant active sites. It also triggers more electron transfer, producing a strong synergistic effect that results in an increase in specific surface area, Olatt/Otol ratio and the number of acidic sites. Boosted by synergistically multidoping effect, the as-prepared Co-NiMo/Cr2O3 catalyst exhibits superior activity in NOx reduction (95 %, 150 °C), which is 3 times that of Cr2O3 derived from pure MOFs under the same condition. This work may shed the light on the design and fabrication of multifunctional nanoporous metal oxide composites materials and inspire the application of polyoxometalates in NOx removal processes.

Chloride ligand stablizes single-atom on nanoporous metal oxides in a pyrolysis process

Pyrolysis-induced single-atom (SA) immobilization is a facile approach for the large-scale synthesis of single-atom materials, which holds promising potential in catalysis. The transition behavior from metal precursor to SA is not yet fully understood. Here, we report that coordinating chloride ligands play a pivotal role in stabilizing Pt/Ir/Ru SA when pyrolyzing their precursors on nanoporous metal oxide (Co3O4, NiO, and Fe2O3). The electrochemical and spectroscopic analysis combined with theoretical calculations suggests a thermal-driven progressive decomposition of metal precursors. Pyrolysis at a critical temperature of 250 ℃ drives the formation of the Ir-O3 motif between the Ir-based precursor and the supporting Co3O4, whereas three residual chloride ligands remain coordinated on the top and prohibit them from reacting with free Ir-containing species. Ir-SA/Co3O4 with an Ir loading of up to 3 at.% is produced. For electrocatalytic oxygen evolution reaction, it delivers a current density of 10 mA/cm2 at an overpotential of only 220 mV, corresponding to 11-fold higher mass activity over their corresponding nanoclusers/Co3O4. Our work highlights the essential role of ligands in the formation of SA, offering new insights into the thermal stability of SA, as well as a new avenue to increasing the loading of SAs.

A Versatile Synthesis Platform Based on Polymer Cubosomes for a Library of Highly Ordered Nanoporous Metal Oxides Particles.

Polymer cubosomes (PCs) have well-defined inverse bicontinuous cubic mesophases formed by amphiphilic block copolymer bilayers. The open hydrophilic channels, large periods, and robust physical properties of PCs are advantageous to many host-guest interactions and yet not fully exploited, especially in the fields of functional nanomaterials. Here, the self-assembly of poly(ethylene oxide)-block-polystyrene block copolymers is systematically investigated and a series of robust PCs is developed via a cosolvent method. Ordered nanoporous metal oxide particles are obtained by selectively filling the hydrophilic channels of PCs via an impregnation strategy, followed by a two-step thermal treatment. Based on this versatile PC platform, the general synthesis of a library of ordered porous particles with different pore structures , tunable large pore size (18-78nm), high specific surface areas (up to 123.3m2g-1 for WO3) and diverse framework compositions, such as transition and non-transition metal oxides, rare earth chloride oxides, perovskite, pyrochlore, and high-entropy metal oxides is demonstrated. As typical materials obtained via this method, ordered porous WO3 particles have the advantages of open continuous structure and semiconducting properties, thus showing superior gas sensing performances toward hydrogen sulfide.

Pengaruh Konsentrasi Oksida Logam CuO Sebagai Superkapasitor Berbasis Karbon Aktif

Supercapacitors are promising energy storage devices in future energy technology. In this research, the primary and applied aspects of supercapacitors are developed. Various techniques have been developed specifically to estimate specific capacitances. Various attempts have been made in the literature to increase the specific capacitance value of the electrode materials. Electrode materials with unique structural and electrochemical properties, such as high capacity and cyclic stability, exhibit good supercapacitor performance. Many new electrode materials have been developed to play an essential role in capacitance behavior. This research focuses on the highly efficient application of nanostructured electrode materials such as nanoporous carbon and metal oxide CuO for supercapacitors. Nanopore carbon is made from coconut shell, which is synthesized using a simple heating method. Next, carbon nanopore and CuO nanoparticle composites were carried out with composition variations of 0.5,10,15, and 20% of the total weight. The results of cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge tests, maximum results were obtained on a composition of 5% CuO nanoparticles with a capacitance of 280 F/gr and a conductivity of 1.14 X 10-2 S/cm. This result is due to an increase in the surface area between the pore surfaces, so more ions are trapped, causing the filling process to take place quickly.

Stainless steel-derived nano-porous oxide: a cost-efficient, stable, and corrosion-resistant hydrogen evolution catalyst

The nanoporous metal oxide structure derived from stainless steel (SS) exhibits exceptional hydrogen evolution reaction activity and remarkable operational resilience, enduring 50 hours of continuous electrolysis.

Transforming Alloys into Au-Loaded Nanoporous Transition Metal Oxide Catalysts for Room Temperature CO Oxidation

Transforming Alloys into Au-Loaded Nanoporous Transition Metal Oxide Catalysts for Room Temperature CO Oxidation

Field tests of a self-sintering, anti-soiling, self-cleaning, nanoporous metal oxide, transparent thin film coating for solar photovoltaic modules

Nanoporous metal oxide ceramic coatings, deposited using sol-gel techniques, have the potential to impart self-sintering and self-cleaning coatings to silicon oxide glass. When used on solar photovoltaic modules, these coatings can impart anti-static properties, improve wetting behavior, and degrade soiling deposits through photocatalytic activity. This paper reports on a field trial of a mixed silicon and titanium oxide thin film coating conducted in the upper midwestern U.S. Coated modules demonstrated increased electrical generation relative to uncoated controls. The results are encouraging for the commercialization of this coating technology, and provide a strong motivation for further research and development efforts.

Carbon-doped metal oxide interfacial nanofilms for ultrafast and precise separation of molecules.

Membranes with molecular-sized, high-density nanopores, which are stable under industrially relevant conditions, are needed to decrease energy consumption for separations. Interfacial polymerization has demonstrated its potential for large-scale production of organic membranes, such as polyamide desalination membranes. We report an analogous ultrafast interfacial process to generate inorganic, nanoporous carbon-doped metal oxide (CDTO) nanofilms for precise molecular separation. For a given pore size, these nanofilms have 2 to 10 times higher pore density (assuming the same tortuosity) than reported and commercial organic solvent nanofiltration membranes, yielding ultra-high solvent permeance, even if they are thicker. Owing to exceptional mechanical, chemical, and thermal stabilities, CDTO nanofilms with designable, rigid nanopores exhibited long-term stable and efficient organic separation under harsh conditions.

Plasma-Synthesis of MOF-Derived Nanoporous Copper Oxides for Solar Thermal Application

Nanoporous Metal oxides (P-MOx) have attracted great attention because of their enhanced performances in e.g., energy storage, catalysis, sensors, solar technology, and biomedicine due to large surface area coupled with good thermal and chemical stability. Existing synthesis techniques of P-MOx suffer from major drawbacks such as longer time and limitation in material choices. Plasma assisted synthesis of metal organic framework (MOF) derived P-MOx can be a rapid and sustainable one-step process and allow a higher degree of flexibility in controlling porosity, pore size distribution and surface properties. Herein, synthesis of nanoporous copper oxides (P-CuOx) was carried out by plasma treating copper-based MOF as a precursor. A systematic study of the transformation of MOF to derived P-CuOx has been carried out by varying the plasma treatment time also the formation of different phases of CuO and Cu2O was investigated. Additionally, a comparative study of properties was done between the plasma-synthesised P-CuOx and pyrolytically synthesised P-CuOx. Transformation process of MOF to P-CuOx was studied using x-ray diffraction (XRD) and Raman analysis. Moreover, morphological properties were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Finally detail optical characterization and solar thermal conversion properties of P-CuOx based nanofluid were studied to test its applicability in solar thermal energy harvesting.

Zinc Nanoparticles Electrodeposited on TiO2Nanotube Arrays Using Deep Eutectic Solvents for Implantable Electrochemical Sensors

This work reports on the electrodeposition of zinc on nanoporous metal oxide titania nanotube arrays (TiO2 NTAs) using a zinc-containing deep eutectic solvent (Zn2+–DES). The effects of substrate morphology and crystallinity, deposition temperature, zinc concentration, and deposition time on the morphology and electrochemical properties of the Zn/TiO2 NTAs were investigated. Two-dimensional zinc nanohexagons (NHexs) with a mean diameter of ∼300 nm and a thickness of 10–20 nm were decorated onto the TiO2 NTAs (with a pore diameter of ∼80 nm and a tube length of ∼5 μm) via electrodeposition at −1.6 V using Zn2+–DES. Cyclic voltammetry tests on the Zn2+–DES electrolyte revealed an electrochemical window of ∼3.5 V, and the diffusion coefficient of Zn2+ was found to be 4.29 × 10–10 cm2 s–1 at room temperature and 7.10 × 10–10 cm2 s–1 at 40 °C. Zinc nucleation on TiO2 NTA substrates followed an instantaneous model. Using a higher electrodeposition temperature increased the nucleation and growth rate of zinc NHexs, while annealing TiO2 NTAs was found to improve their uniformity and morphology. During the initial stage of deposition, hexagonal close-packed zinc NHexs were found to preferentially grow on tetragonal anatase TiO2 NTAs. The electrodeposition of zinc resulted in lowering the impedance and improving the overall electrochemical properties of TiO2 NTAs. The Zn/TiO2 NTAs developed in this study offer a promising electrocatalyst material system for implantable electrochemical sensors.

Synthesis, Physicochemical Characterization and Applications of Advanced Nanomaterials

This Special Issue highlights the last decade's progress regarding new nanostructured materials. In this regard, the development of nanoscale syntheses and innovative characterization tools that resulted in the tailored design of nanostructured materials with versatile abilities in many applications were investigated. Various types of engineered nanostructures, usually metal nanoparticles or nanoporous metal oxides, have been synthesized for various applications. This Special Issue covers the state-of-the-art of advanced nanoparticles in many disciplines (chemistry, pharmacy, nanomedicine, agriculture, catalysis, and environmental science). The crystallite sizes depended on the annealing temperature and type of doping ion. A combination of rigid and soft particles could simultaneously enhance both the tensile properties and the fracture toughness, which could not be achieved by the single-phase particles independently. The surface charge and in vitro corrosion resistance are key parameters characterizing biomaterials in the interaction of the implant with the biological environment. Solar energy in the presence of a photocatalyst can be effectively converted into electricity/fuel, break down chemical and microbial pollutants, and help water purification. The saturation magnetization, remanent magnetizations, coercivity, and anisotropy were found to depend on the doping ion, annealing temperature, and particle size. The efficiency of the photocatalysis reaction depends on several factors, including light absorption capacity/light intensity, the type of photocatalyst used, the concentration of a photocatalyst and contaminant particles, the pH of the reaction medium, etc. The variety of color pigments and coloring properties of the targeted application in the ceramic industry was also of interest.

Structural transformation induced twinning for enhanced conversion reaction of vacancy-ordered metal oxides with Li ions

Metal oxide anode materials based on conversion reaction usually deliver a capacity much higher than that of commercial graphite anodes in lithium-ion batteries (LIBs), and the porous forms of the materials can effectively alleviate volume change associated with (de)lithiation. In this work, tetragonal γ-Fe2O3, which is a vacancy-ordered superstructure containing large vacancy clusters, is studied as the representative of intrinsic nanoporous metal oxide anode materials of LIBs. γ-Fe2O3 exhibits a reversible capacity higher than the theoretical value in initial cycles, but a steady capacity same as that of α-Fe2O3. In lithiation, γ-Fe2O3 first transforms irreversibly to an ordered rock salt Li1-xFe1+xO2 (LiTiO2 type), and the Li1-xFe1+xO2 is converted reversibly into Li2O and Fe0 upon further lithiation: γ-Fe2O3+Li→Li1-xFe1+xO2+Li ↔ Fe0+Li2O. The alternate stacking of dense tetrahedral layers and porous octahedral layers in γ-Fe2O3 enables the simultaneous formation of Li1-xFe1+xO2 phases with different Li contents in a single particle and triggers structure twinning, accounting for fast reaction and likely high capacity in initial cycles. The structural evolution disclosed in γ-Fe2O3 not only updates the understanding of conversion reactions of vacancy-ordered metal oxides, but also offers an innovative approach for the fabrication of twinning structures in metal oxides including cathode materials.

Synthesis of Silicotungstic Acid/Ni-Zr-O Composite Nanoparticle by Using Bimetallic Ni-Zr MOF for Fatty Acid Esterification

In this study, the bimetallic Ni-Zr MOF-derived nickel-zirconium oxide (Ni-Zr-O)-impregnated silicotungstic acid (HSiW) nanocomposite catalyst (HSiW@Ni-Zr-O) was prepared via a hydrothermal procedure followed by a pyrolysis treatment, and its structural, morphological, and surface components and oxidation states were characterized by using XRD, FTIR, TPD-NH3, SEM, TEM, N2 physisorption, and XPS analyses. Then, the nanocomposite catalysts were successfully applied to the esterification of oleic acid (OA) with methanol. According to its characteristics, the obtained HSiW@Ni-Zr-O-1 catalyst would generate larger pores, a higher acidity, and active interfaces at the calcining temperature of 300 °C. Therefore, HSiW@Ni-Zr-O-1 exhibits an excellent catalytic activity of 95.2% under optimal reaction conditions. Additionally, the catalyst can be reused with a good catalytic activity after nine cycles. This study highlights the opportunity of using bimetallic MOFs as precursors to the synthesis of highly nanoporous metal oxide, which supports the larger-industrial scale production of biofuels.

Preparation of Ordered Nanoporous Indium Tin Oxides with Large Crystallites and Individual Control over Their Thermal and Electrical Conductivities.

Metal oxides are considered suitable candidates for thermoelectric materials owing to their high chemical stabilities. The formation of ordered nanopores within these materials, which decreases thermal conductivity (κ), has attracted significant interest. However, the electrical conductivity (σ) of reported nanoporous metal oxides is low, owing to electron scattering at the thin pore walls and many grain boundaries formed by small crystallites. Therefore, a novel synthesis method that can control pore walls while forming relatively large crystallites to reduce κ and retain σ is required. In this study, we used indium tin oxide (ITO), which is a typical example among metal oxides with high σ. Nanoporous ITOs with large crystallite sizes of several hundred nanometers and larger were successfully prepared using indium chloride as a source of indium. The pore sizes were varied using colloidal silica nanoparticles with different particle sizes as templates. The crystal phase and nanoporous structure of ITO were preserved after spark plasma sintering at 723 K and 80 MPa. The κ was significantly lower than that reported for bulk ITO due to the phonon scattering caused by the nanoporous structure and thin pore walls. There was a limited decrease in σ even with high porosity. These findings show that κ and σ are independently controllable through the precise control of the structure. The control of the thickness of the pore walls at tens of nanometers was effective for the selective scattering of phonons, while almost retaining electron mobility. The remarkable preservation of σ was attributed to the large crystallites that maintained paths for electron conduction and decreased electron scattering at the grain boundaries.

Production of green electricity from strained BaTiO3 and TiO2 ceramics based hydroelectric cells

Electricity generation from water molecules dissociation instantly without use of any chemical/light by invented hydroelectric cell (HEC) has emerged a new field of green energy generation without disturbing the environment. Specially engineered nanoporous and oxygen deficient metal oxides have already shown drastic capability of water dissociation at room temperature. In this direction we have heat treated TiO2 (TO) and synthesized BaTiO3 (BTO) in which oxygen defect induced strain through processing has been obtained. Oxygen vacancies produced in TO and BTO have been confirmed by Photoluminescence spectroscopy (PL). The cation-oxygen vacancy pairs (Ti+3-Vo) on the BTO surface provide acid-base pair to attract polar water molecules to get chemidissociated into OH− and H3O+ ions. Further chemisorbed surface hydroxyl ions provide high surface charge potential to physisorbed multilayer of water molecules dissociation and some of H3O+ ions get trapped inside the nanopores. The trapped ions inside nanopores generate enough charge potential to further physi-dissociate adsorbed water molecules. Titanium dioxide samples exhibit increase in strain that has been estimated from the X-ray diffraction results. Bond length and bond angle in both of TiO2 (TO) and BaTiO3 (BTO) decrease while strain increases in their lattice structure. A circular disc of 2 cm diameter and 1 mm thickness of TiO2 and BaTiO3 have been fabricated as hydroelectric cell. BTO based HEC of area 3.14 cm2 generated maximum current 3.66 mA and voltage 0.975 V. Varying the synthesis parameters to produce more defects in the compound may further increase electricity generation. Perovskite based HEC is very stable, repetitive and eco-friendly technique for portable green electricity generation.

Biocompatibility of strontium incorporated ceramic coated titanium oxide implant indented for orthopaedic applications

Titanium and its alloys are the most commonly used materials for manufacturing orthopaedicimplants. Various surface modifications are done in titanium alloys to improve osseointegration as well as for long term success of endosseous implants. In the present study preclinical safety evaluation of two nanoporous mixed metal oxide bone implant materials, TiO2-Nb2O5 (TN) and Sr-HAP modified TN (TNS) were assessed by in vitro and in vivo methods. The surface morphological analysis of fabricated materials was done by XRD, IR and SEM. The biocompatibility evaluations performed were In vitro cytotoxicity tests using L929 cells, Assessment of hemolytic properties of materials and Test for local effects after implantation in bone as per international standards. The results of the study conclude that the materials, TN and TNS are non-cytotoxic, non-hemolytic and biocompatible and can be used safely for orthopaedic applications.

Water splitting on the mesoporous surface and oxygen vacancies of iron oxide generates electricity by hydroelectric cell

The impact of water splitting by specially processed maghemite/iron oxide for generating ecologically sustainable, low-cost green electricity is a vital step. In the present work, a facile and a low-cost chemical synthesis technique has been adopted to produce versatile, oxygen deficient, mesoporous maghemite (iron oxide) nanostructure. The maghemite nanoparticles have been synthesized by the oxidation of magnetite nanoparticles, using a coprecipitation technique followed by heat treatment at elevated temperature 350 °C for 2 h. In the modified process, oxygen (VO) and iron vacancies (VFe) in maghemite have been systematically created. The VFe sites generated at octahedral sites due to Fe2+ ion oxidation has been estimated by Raman and X-ray photoelectron spectroscopy (XPS). Water splitting is prominently occurring at VO sites. Splitting of polar water molecules on the surface oxygen vacancies of nanoporous ferrite and metal oxide pellets has been translated into a primary hydroelectric cell by attaching two dissimilar electrodes to the pellets to generate an electric current. However, preferable associative water adsorption on VFe sites have been confirmed by unique XPS bands with multilayered physisorbed water adsorption modes. The role of VFe, VO sites in water molecule dissociation, and further dissociated ions diffusion kinetics through respective maghemite and magnetite pellets has been thoroughly explored by dielectric measurements. Maghemite based hydroelectric cell (HEC) has delivered a maximum current of 19 mA and emf 0.85 V by using only 200 μL water. The maximum electrical power 16.15 mW delivered by maghemite HEC is 0.58, 0.42 times lower than the respective magnetite, hematite HECs. The magnitude of dielectric relaxation is reduced in maghemite due to preferable associative water adsorption on VFes compared to other iron oxides. Hence, lesser VO concentration, larger average pore size along with the presence of hydrophobic VFe sites are responsible for the lower performance of maghemite based HEC. Variation in spinel magnetite, maghemite HEC performance has been analysed by simulating its V–I characteristic curve. The electricity generation by maghemite HEC is reduced due to lower VO concentration along with the presence of hydrophobic VFe sites reducing the overall number of dissociated ions. Hydroelectric cell from earth- abundant iron oxide is an eco-friendly, bio-compatible, and cost-effective green energy source by water splitting at room temperature.

Application of Molybdenum oxide nanoparticles in H2S removal from natural gas under different operational and geometrical conditions

Microporous and nanoporous metal oxides are potential adsorbents for separating H2S from natural gas. Structured porous adsorbents have the potential to improve the energy and production costs in gas separation and catalysis applications by providing higher production rates. Zinc, Manganese, and Iron oxide nanoparticles are among the most potential and most extensively employed materials. Applying this framework, other novel metal oxides have been recognized for separation of H2S from representative H2S/CH4. In the present study, we investigate the performance of Molybdenum oxide nano-particles as an adsorbent for H2S removal and compare it with the performance of zinc oxide nano-particles. The effects of operating conditions such as temperature (65–89 °C), pressure (10–19 bar), initial concentration of H2S in the feed stream (38–73 ppm), and space velocity (0.018–0.045 m s−1) on H2S adsorption from sour gas are evaluated. Our analysis shows that Molybdenum oxide nano-particles have an adsorption capacity of 0.081 and 0.074 g H2S/g Molybdenum oxide in low temperature and low concentration of H2S using non-spherical and spherical Molybdenum oxide sorbent, respectively. Proceeding by two adsorption isotherms, the Langmuir and Freundlich isotherms, analysis of variance displayed that both models can fit the adsorption data of H2S on Molybdenum oxide nanoparticles very well, while the Freundlich isotherm seems to provide R2 value of 0.98–0.99, indicating a better prediction of our experimental data.

(Invited) Use of Periodic Pulses and Non-Native Substrates to Form Nanoporous Metal Oxide Films By Anodization

Electrochemical anodization is a robust and versatile fabrication method to form arrays of ordered nanopores and nanotubes in a number of metal oxides including Al2O3, TiO2, Ta2O5, Nb2O5, Fe2O3, ZnO, WO3, NiO and ZrO2 [1]. The key advantages of anodization are simplicity, low cost, solution-based processing, large area compatibility and mass-producibility. The anodic formation of oriented and aligned nanostructures has also been extended to metal chalcogenides [2]. A majority of the aforementioned metal oxide and chalcogenide compounds exhibit semiconducting behavior. Consequently, the anodically formed nanostructures in these compounds are high surface area semiconductors (typically after a crystallizing anneal) that are nearly ideal for the formation of electronic heterojunctions for sensing, photocatalysis, photovoltaics and light emission [3-5]. An emerging frontier in electrochemical anodization consists of imparting nanophotonic enhancement(s) to the semiconducting properties of highly ordered metal oxide nanopore (MONPAs) and nanotube arrays (MONTAs). Examples of such nanophotonic enhancements include the bottom-up, solution-based growth of photonic crystals, metamaterials and plexcitonic substrates. Nanophotonic enhancements enable light trapping in heterojunction photocatalysts and photovoltaic devices in order to harvest solar radiation more completely. Nanophotonic enhancements can also be used to control the directionality, intensity and lifetime of photoluminescence, and generate high Q-factor collective resonances to boost sensitivity in photodetectors, immunoassays and small molecules SERS-based sensing. The use of low frequency pulses in the anodization process can be used to periodically modulate the diameter of nanopores and the wall-thickness of nanotubes in the depth direction [6]. Pulsed anodization of metal foils results in metal oxide nanostructures with a periodic refractive index which can be used to fabricate one-dimensional photonic crystals (1D-PhCs) by suitably adjusting the amplitude and pitch of the periodic features. Work in this area has focused on either using pulsed currents or pulsed voltages during anodization to form 1D-PhCs. One major limitation of the anodic growth of photonic crystals is the lack of control over the stop-band center frequency and the full width at half-maximum (FWHM) of the photonic stop-band resonances. We introduce a new technique, which involves periodically varying the charge supplied to the anodization process. The charge-controlled pulsed anodization process enables superior control over the morphology of the anodic 1D-PhCs and can be used to generate narrower resonances at desired wavelengths. Illustrative examples of the utility of these 1D-PhCs in photocatalysts and sensors are presented in this Invited Lecture. Another frontier in the anodic formation of metal oxide nanostructures consists of the use of thin metal films on non-native substrates as anodization substrates. Currently, the overwhelming majority of anodization processes use metal foils that are hundreds of micrometers to millimeters in thickness as substrates. For optoelectronic applications, the use of such metal foils is highly limiting due to the opaque substrates preventing light in-coupling and light out-coupling into the nanopore/nanotube array from the substrate direction. Therefore, the formation of MONPAs & MONTAs on transparent substrates such as fluorine-doped tin oxide(FTO)-coated glass and indium tin oxide(ITO)-coated glass, is highly desirable [7]. This Invited Talk will showcase anodically formed MONPAs & MONTAs of TiO2, Ta2O5 and NiO on silicon and conductive glass substrates while also presenting prototypical optoelectronic applications of MONPAs & MONTAs on non-native substrates. REFERENCES [1] A. Ghicov and P. Schmuki, Chem. Commun. 0, 2791-2808 (2009). [2] P. Kar, S. Farsinezhad, X. Zhang and K. Shankar, Nanoscale 6, 14305-14318 (2014). [3] P. Kar, A. Pandey, J.J. Greer and K. Shankar, Lab on a Chip 12, 821-828 (2012). [4] S. Farsinezhad, H. Sharma and K. Shankar, Phys. Chem. Chem. Phys. 17, 29723-29733 (2015). [5] P. Qin, M. Paulose, M. I. Dar, T. Moehl, N. Arora, P. Gao, O. K. Varghese, M. Grätzel and M. K. Nazeeruddin, Small 11, 5533-5539 (2015). [6] X. Zhang, F. Han, B. Shi, S. Farsinezhad, G.P. Dechaine and K. Shankar, Angew. Chem. Int. Ed. 51, 12732-12735 (2012). [7] S. Farsinezhad, A. Mohammadpour, A. N. Dalrymple, J. Geisinger, P. Kar, M. J. Brett and K. Shankar, J. Nanosci. Nanotechnol. 13, 2885-2891 (2013). Figure 1