3DOM Structure Research Articles

YSZ-based NO2 Mixed Potentiometric Sensor with Three-Dimensional Ordered Porous Structure

This study presents the preparation of a nitrogen dioxide (NO2) gas sensor based on yttrium-stabilized zirconia (YSZ) using a hard-template method and evaporation self-assembly technology. The sensing electrode employed is nickel oxide, and the sensor exhibits an efficient three-phase boundary. The study systematically investigates the effects of changing the three-phase reaction boundary on the gas-sensing performance of the sensor. A three-dimensional (3D) ordered macroporous (3DOM) structure was deposited on a YSZ substrate using the hard template method to obtain an efficient three-phase boundary. At 450 °C and 100 ppm NO2, the response value of the sensor with a 3D-ordered porous structure was 38.71 mV, which is 1.91 times the response value observed for the untreated YSZ-based sensor (20.3 mV), and the sensitivity significantly improved. In addition, a sensor with a 3D-ordered structure exhibits good 2 selectivity, and long-term stability. The improvement in the sensitivity of the sensor can be attributed to an increase in the area of the three-phase reaction boundary and an increase in the number of active sites in the electrochemical reaction.

Ordered porous nitrogen-vacancy carbon nitride for efficient visible-light hydrogen evolution

Photocatalytic H2 evolution is a promising technology which could be instrumental in producing clean hydrogen energy. In regard to the photocatalyst, its band structure, morphology and light utilization have a significant influence on the H2 evolution rate and stability. Herein, a three-dimensional ordered macroporous nitrogen-vacancy carbon nitride (3DOM V-CN) photocatalyst was developed by combining vacancies with 3DOM structure for visible-light photocatalytic H2 evolution. This strategy preserved the structural properties of 3DOM to improve the light utilization and the specific surface area of the photocatalysts. Moreover, constructing suitable vacancies could trap electrons to facilitate the separation of photogenerated carriers, and extend the light absorption region of the photocatalysts by adjusting band structure, thus improving photocatalytic activity. Compared with CN (0.3 mmol h−1 g−1), 3DOM V-CN demonstrated a superior photocatalytic H2 evolution rate of 2.3 mmol h−1 g−1 (λ ≥ 420 nm) while possessing excellent stability. This work provides an effective and low-cost strategy for the design of the photocatalysts with high activity and stability by simultaneously tuning the band structure and morphology.

Engineering three-dimensionally ordered mesoporous structure of TiO2 for the fast responsive NH3 gas sensor at ambient conditions

Engineering TiO2 nanostructures with a unique fast responsive property for NH3 detection under ambient conditions remains a great challenge in the sensor industry as TiO2 is active at an elevated temperature of more than 200 °C. Despite this obstacle, in this work, the hierarchical three-dimensional ordered mesostructured (3DOM) of TiO2 with designed morphology and pore orientation was developed for the NH3 gas sensor at room temperature. The hybrid TiO2 templates, polymethyl methacrylate (PMMA) and pluronic 123 (P123), were employed during an evaporation-induced self-assembly synthesis. The 3DOM TiO2 was identified to be in a pure anatase phase and showed a honeycomb-like morphology with the walls made of well-connected fine TiO2 particles. The micelle formation time of P123 and the size of PMMA affected the thickness of well-connected nanoparticles of 3DOM TiO2. The optimized micelle formation time for producing the highest sensitivity to the NH3 gas of the P123 and the PMMA size was 15 h and 250 nm, respectively. The NH3 gas sensors were further engineered by laminating the suspended 3DOM TiO2 on a Cu screen printing chip. Interestingly, the low detection limit of 0.1 ppm of NH3 gas sensing was obtained at ambient conditions. Moreover, the systematic gas diffusion pathway with fast response and the grain-controlled transducer process were enhanced when using the 3DOM TiO2 compared to the pristine TiO2 nanoparticles. This work clearly demonstrates that the engineering-designed hierarchical 3DOM structure could provide a fast responsive and low detection limits NH3 sensors at ambient conditions.

Cobalt-loaded three-dimensional ordered Ta/N-doped TiO2 framework as conductive multi-functional host for lithium-sulfur battery

The low electrical conductivity of sulfur and severe shuttling effect of lithium polysulfides (LiPSs) have hindered the practical application of lithium-sulfur (Li-S) batteries. In this work, a conductive Ta/N co-doped TiO2 framework featured with three-dimensional ordered macroporous (3DOM) structure embedded with ZIF-67 derived Co-anchored N-doped carbon (Co-NC) is synthesized as efficient sulfur host material in Li-S batteries. The 3DOM Ta/N-TiO2 backbone has good structural stability, which benefits the electrolyte penetration and sulfur accommodation. Meanwhile, the Ta/N co-doping not only improves the conductivity of TiO2, but also strengthens the adsorption of LiPSs. In addition, the embedded Co-NC increases the active site of 3DOM skeleton towards LiPSs conversion, facilitates the diffusion of Li+ ion, and at the same time provides additional microspores for sulfur confinement. Attributed to these features, the sulfur electrode based on 3DOM Ta/N-TiO2@Co-NC achieves excellent electrochemical performance. The S/3DOM Ta/N-TiO2@Co-NC cell maintains a discharge capacity of 789.2 mAh g−1 after 500 cycles at 1C with a low decay rate of 0.06 % per cycle. Additionally, an initial area capacity of 5.67 mAh cm−2 is obtained under areal sulfur loading of 6.55 mg cm−2. This multistage porous sulfur cathode design has the potential to expedite the development of feasible Li-S battery.

A novel macro-meso-micro intimate heterogeneous structure constructed 3DOM TiO2/rGO/TiN composite for efficiently solar photocatalysis degradation of organic dye pollutants

The new three-dimensionally ordered macroporous titanium dioxide/reduced graphene oxide/titanium nitride (3DOM TiO2/rGO/TiN) ternary nanocomposites are designed based on the pore structure of 3DOM for efficient photocatalytic dye degradation. A series of structural, optical, and photoelectrochemical characterizations demonstrate that the remarkably improved photocatalytic performance is attributed to the combined effects of macro-meso-micro architecture, abundant reactive sites, improved light response range, and efficient photogenerated charges-holes pair separation and transport. By optimizing the loading amounts of rGO and TiN, 3DOM TiO2/10%rGO/5%TiN nanocomposite exhibits the highest photocatalytic degradation activity, which is 7.4 times higher than 3DOM TiO2. Additionally, the 3DOM TiO2/rGO/TiN ternary photocatalyst shows excellent acid-base resistance and reusability. The mechanism by which 3DOM structure, 2D rGO, and TiN synergy enhance the TiO2 photocatalytic performance was fully revealed comprehensively. This work provides an effective strategy for designing TiO2-base macro-meso-micro intimate heterogeneous structure for photocatalysis degradation of dyes.

Achieving Functionality and Multifunctionality through Bulk and Interfacial Structuring of Colloidal-Crystal-Templated Materials.

Over the past 25 years, the field of colloidal crystal templating of inverse opal or three-dimensionally ordered macroporous (3DOM) structures has made tremendous progress. The degree of structural control over multiple length scales, understanding of mechanical properties, and complexity of systems in which 3DOM materials are a component have increased substantially. In addition, we are now seeing applications of 3DOM materials that make use of multiple features of their architecture at the same time. This Feature Article focuses on the different properties of 3DOM materials that provide functionality, including a relatively large surface area, the interconnectedness of the pores and the resulting good accessibility of the internal surface, the nanostructured features of the walls, the structural hierarchy and periodicity, well-defined surface roughness, and relative mechanical robustness at low density. It provides representative examples that illustrate the properties of interest related to applications including energy storage and conversion systems, sensors, catalysts, sorbents, photonics, actuators, and biomedical materials or devices.

Three-dimensionally ordered macroporous (3DOM) structure promoted the activity and H2O poisoning resistance of CeMn/3DOM-TiO2 catalyst in NH3-SCR

NH3-SCR is an effective mean of NOx removal in the non-electric industry, however, the high activation temperature and poor H2O resistance of SCR catalysts posed a barrier to its application. In this work, a series of three-dimensionally ordered macroporous (3DOM) catalysts were synthesized via a colloidal crystal template (CCT) method, and various characterizations were carried out to explore the physicochemical property of catalysts. The experiment results reveal that Ce0.2Mn0.2/3DOM-TiO2 catalyst presents the excellent low-temperature catalytic activity of nearly 100% at 100 °C. Furthermore, the enhanced H2O resistance is achieved, certified by the unaffected NO remove at 150 °C in the participation of 15 vol% H2O. The characterizations results exhibit that the improved dispersion of the active component and enhanced redox ability are conducive to the low-temperature catalytic activity. N2 adsorption and desorption experiments indicate that catalyst with 3DOM support possesses a larger pore diameter and specific surface area, which may weaken the condensation of H2O in the microporosity of catalysts and improved the H2O resistance of the catalyst. In situ DRIFTS results manifest that Ce0.2Mn0.2/3DOM-TiO2 catalyst could not only absorb more NH3 and generate more surface-active sites, but inhibit the competitive adsorption between H2O and SCR reactants.

A COF-coated ordered porous framework as multifunctional polysulfide barrier towards high-performance lithium-sulfur batteries

The practical application of lithium-sulfur batteries (LSBs) is still hindered by the shuttle effect of lithium polysulfides (LiPS) and slow sulfur conversion kinetics. Herein, a LiPS inhibited covalent organic framework (COF)-coated conductive porous metal oxide design strategy is proposed towards the development of efficient and durable sulfur cathode in LSBs. This strategy is demonstrated by coating a TpPa-1 COF layer on cobalt-decorated titanium oxynirtide (TiOxNy) with a three-dimensional ordered microporous framework (3DOM) structure. In this strategy, the oxygen-deficient TiOxNy framework ensures a good conductivity and structural stability of the cathode during the charge/discharge process. The 3DOM macrospores provide a high capacity for sulfur accommodation and exposes active interfaces, whereas the coated TpPa-1 COF featured with ultrafine microspore offer an effective confinement of LiPS within the 3DOM framework, mitigating its shuttling effect. At the same time, the Co embedded in 3DOM TiOxNy servers as efficient catalyst promoting the sulfur electrochemical reaction. Attributed to these structural superiorities, the 3DOM TpPa-1@Co/TiOxNy/S cathode exhibits excellent performance even under high sulfur loading and low electrolyte condition. This work of using microporous COF coating with conductive macroporous metal oxides offers an effective alternative strategy for the design of practical sulfur battery.

Shape-Preserving Transformation of Electrodeposited Macroporous Microparticles for Single-Particle SERS Applications

Microparticles composed of bicontinuous and ordered macropores are important in many applications. However, rational integration of ordered macropores into a single crystalline microparticle remains a challenge. Here, we report a method to prepare three-dimensionally ordered macroporous (3DOM) Ag7O8NO3 micropyramids via selectively cementing the colloidal crystal templates via an electrochemical method and their shape-preserving transformation into 3DOM Ag micropryamids formed by Ag nanoparticles via a chemical reduction process. The interconnected macropores facilitated the transportation and enrichment of the analyte molecules into the 3DOM Ag micropyramids. The dense Ag nanoparticles on the skeletons of the 3DOM Ag micropyramids provided strong electromagnetic fields. Taken together, a 3DOM Ag micropyramid as a kind of single-particle surface-enhanced Raman scattering (SERS) sensing substrate demonstrated high SERS sensitivity and outstanding SERS signal reproducibility. We explored the application of 3DOM Ag micropyramids in SERS detection of biomolecules (e.g., adenosine, adenine, hemoglobin bovine, and lysozyme) and proved their potentials in distinguishing exosomes from tumor and non-tumor cells. The method can be extended to prepared 3DOM structures of other materials with promising applications in sensing, separation, and catalytic fields.

The three-dimensionally ordered microporous CaTiO3 coupling Zn0.3Cd0.7S quantum dots for simultaneously enhanced photocatalytic H2 production and glucose conversion

Glucose conversion assisted photocatalytic water splitting technology to simultaneously produce H2 and high value-added chemicals is a promising method for alleviating the energy shortage and environmental crisis. In this work, we constructing type II heterojunction by in-situ coupling Zn0.3Cd0.7S quantum dots (ZCS QDs) on three-dimensionally ordered microporous CaTiO3 (3DOM CTO) for photocatalytic H2 production and glucose conversion. The DFT calculations demonstrate that substitution of Zn on the Cd site improves the separation and transmission of photogenerated carriers. Therefore, 3DOM CTO-ZCS composite exhibits best H2 production performance (2.81 mmol g-1h−1) and highest apparent quantum efficiency (AQY) (5.56 %) at 365 nm, which are about 47 and 18 times that of CTO nanoparticles (NPs). The improved catalytic performance ascribed to not only good mass diffusion and exchange, highly efficient light harvesting of 3DOM structure, but also the efficient charges separation of type Ⅱ heterojunction. The investigation on photocatalytic mechanism indicates that the glucose is mainly converted to gluconic acid and lactic acid, and the control reaction step is gluconic acid to lactic acid. The selectivity for gluconic acid on 3DOM CTO-ZCS is 85.65 %. Our work here proposes a green sustainable method to achieve highly efficient H2 production and selective conversion of glucose to gluconic acid.

CdS-loaded three-dimensional ordered macroporous composite material In2O3-TiO2: Construction of type II heterostructure and enhancement of photocatalytic performance

With the help of polystyrene template, the indium oxide-titanium dioxide (In2O3-TiO2) composite with a three-dimensional ordered macroporous (3DOM) structure was synthesized first, then cadmium sulfide (CdS) was loaded on the surface, and eventually 3DOM CdS/In2O3-TiO2 composites were prepared. 3DOM CdS/In2O3-TiO2 mainly presents the anatase structure of TiO2, while CdS and In2O3 exist in the composite with low crystallinity. Compared with the monomer, the light absorption performance of the composite is significantly improved. The regular and well-organized three-dimensional ordered macroporous structure broadens the absorption of visible light, optimizes the charge transfer efficiency, and extends the photogenerated carrier life. The presence of heterojunctions in 3DOM CdS/In2O3-TiO2 leads to enhanced performance of photodegradation and photolysis of water for hydrogen production. In particular, the hydrogen production of 3DOM CdS/In2O3-TiO2 is 40.7 times that of the commercially available P25. Through the capture experiments, the possible photocatalytic reaction mechanism was speculated.

High-performance Ce doped three-dimensional ordered macroporous Co-based catalysts on CO oxidation

3D-Co16Ce1Oy had the highest CO catalytic performance and the lowest Ea attributed to the synergistic promotion of the 3DOM structure and Ce doping.

Photothermal catalytic H2 production over hierarchical porous CaTiO3 with plasmonic gold nanoparticles

The synergistic promotion by photocatalysis and thermocatalysis is a promising approach for sustainable hydrogen (H2) production. Herein, we rationally design a perovskite-based catalyst with three-dimensionally ordered macroporous structure (3DOM CaTiO3-Au) for photothermal catalytic H2 production from different substrates. The hierarchical 3DOM structure facilitates light harvesting and mass diffusion of the substrates, while the gold nanoparticles (Au NPs) promote charge separation. The photogenerated and hot electrons are oriented accumulated on the surface of Au NPs. The non-metallic gold species [Au(I)] show more activity for H2 evolution. As a result, 3DOM CaTiO3-Au exhibits excellent activity for H2 production from glycerol and other substrates with hydroxyl groups. The present work demonstrates a feasible approach to improve sustainable H2 production by rationally designing and fabricating efficient photothermal catalysts.

Novel preparation method, catalytic performance and reaction mechanisms of PrxMn1−xOδ/3DOM ZSM-5 catalysts for the simultaneous removal of soot and NOx

Three dimensionally-ordered macroporous (3DOM) ZSM-5 zeolite catalysts with hierarchical pore structures have obvious advantages for the catalytic reaction systems containing reactants with different sizes. However, due to the stringent preparation conditions and confined crystallization space, the successful preparation of 3DOM ZSM-5 remains challenging. Herein, we report a novel method for the preparation of 3DOM ZSM-5 zeolite, termed the steam seed-assisted colloid crystal template (SSAC) method. The SSAC method avoids the growth of ZSM-5 crystals based on the confinement effect of the interstices of the polymethylmethacrylate (PMMA) template. The crystallization temperature of ZSM-5 is lower than the glass transition temperature of PMMA, which facilitates the formation of the 3DOM structure. Using 3DOM ZSM-5 as a support, a series of PrxMn1-xOδ/3DOM ZSM-5 catalysts were prepared via incipient wetness impregnation. These catalysts exhibited good catalytic performance for the simultaneous removal of soot and NOx, which can be attributed to the unique hierarchical pore structure, excellent redox properties, the sufficient active oxygen species and appropriate acid sites of overall catalysts. Among the synthesized catalysts, Pr0.2Mn0.8Oδ/3DOM ZSM-5 achieved the highest catalytic activity with a low soot combustion temperature of 417 °C and a wide temperature window of 128 °C-288 °C at 90% NO conversion. Finally, we proposed reaction mechanisms for the catalysts under different temperatures based on the in situ characterization results, kinetic measurements and DFT calculations.

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Three-dimensional ordered macroporous design of heterogeneous nickel-iron phosphide as bifunctional electrocatalyst for enhanced overall water splitting

Developing high-performance oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) bifunctional electrocatalysts is essential for overall water splitting. Herein, heterogeneous engineering-induced strategy was demonstrated by the synthesis of bimetallic Ni2P/FeP/Fe2P heterostructure with three-dimensional ordered macroporous structure (3DOM-Ni2P/FexP) as bifunctional catalyst. The heterogeneous interfaces formed by the three distinct phases can adjust the electron distribution and create abundant active sites to improve the catalytic performance. The 3DOM structure provides large specific surface area and good mass transfer for electrocatalytic reaction occurring at the solid-gas-electrolyte multiphase interfaces. Accordingly, the 3DOM-Ni2P/FexP showed remarkable OER and HER electrocatalytic activity in 1 M KOH electrolyte. Moreover, it demonstrates that the 3DOM-Ni2P/FexP turns out oxidation and transformation during the OER process. Computational results reveal the synergy of the converted Fe2O3/NiOOH, promoting the OER reaction energetics. In addition, an alkaline electrolyzer with the 3DOM-Ni2P/FexP as both the cathode and anode achieves excellent overall water splitting performance, with only 1.54 V voltage to obtain the current density of 10 mA cm−2. This present study gives a novel concept of heterogeneous engineering-induced bimetallic phosphide with macroporous structure design towards the high-performing OER and HER bifunctional electrocatalysts evolvement.

Preparation of three-dimensional ordered macroporous Ag/LaFeO3 and heterogeneous photo-Fenton degradation of penicillin G potassium

ABSTRACT 3DOMLaFeO3 was prepared by template method combined with sol-gel method using monodisperse polystyrene (PS) microspheres as template, and Ag/3DOMLaFeO3 perovskite catalyst was prepared by impregnation method combined with sodium borohydride reduction method. The catalysts were characterised by means of TG, XRD, SEM, BET, XPS, UV-vis DRS, etc. The photo-Fenton catalytic performance, stability and catalytic reaction mechanism of Ag/3DOMLaFeO3 were studied with penicillin G potassium (PEN G) as the model pollutant. The results indicated that the as-prepared Ag/3DOMLaFeO3 exhibited a three-dimensional ordered macroporous (3DOM) structure, and the light capture and mass transfer were enhanced through abundant pores and large specific surface area. Based on the surface plasmon resonance effect (SPR), Ag loading enhanced the absorption of the material in the visible light region, and inhibited the recombination of photogenerated carriers, which improved the photocatalytic performance of 3DOMLaFeO3 under visible light. Under the conditions of hydrogen peroxide dosage of 1.5 mL·L−1, initial pH of 5, PEN G initial concentration of 100 mg·L−1, catalyst dosage of 300 mg·L−1, xenon lamp irradiation, the degration ratio of PEN G and the removal rate of TOC reached 99.99% and 85.45% within 120 min, respectively. In addition, it had a wide range of pH application, excellent stability and practical application value. The quenching experiment and ESR test showed that ·OH and ·O2 − were the reasons for high catalytic degradation. The least square method was used to fit the experimental data, and the results displayed that the degradation of PEN G was approximately in line with the first-order kinetic reaction.

G-C3N4 templated synthesis of 3DOM SnO2/CN enriched with oxygen vacancies for superior NO2 gas sensing

Materials with three-dimensional ordered macroporous (3DOM) structures possess large surface area and abundant macropores, providing more surface active adsorption sites and target gas transport channels. Herein, g-C3N4 was utilized as a hard template to fabricate 3DOM SnO2/CN composites. After calcinating the g-C3N4-metal ions hybrids in air, most of the carbon and nitride sources were removed, leaving metal oxides with the original 3DOM structures. The residual carbon and nitride also generated amorphous CN species, significantly boosting the conductivity of the mixed composites. Moreover, large amounts of oxygen vacancy defects were also created after the pyrolysis treatment. Sensing results displayed that all SnO2/CN composites under different heating rates displayed excellent sensing response to NO2 gas. Excitingly, sensors with 10 °C min−1 heating rate exhibited a superior response of 926 to 10 ppm NO2 gas at room temperatures (RT, 25 °C) and a low detection limit of 15 ppb. Such high NO2 sensing performance was caused by the open 3DOM structures and abundant oxygen vacancies. Most importantly, this work provides a novel approach to fabricate sensing materials with 3DOM structures and will also promote the practical application of NO2 sensors.

A novel three-dimensionally ordered macroporous aerogel for capturing radioactive gaseous iodine

To further improve the adsorption capacity of radioiodine in nuclear industry waste gas, the sol-gel combined with colloidal crystal template method was used to successfully introduce a three-dimensionally ordered macroporous (3DOM) structure into the silver-silica aerogel. The effects of the 3DOM structure on the micropore surface area, phase composition, iodine capture capacity and regeneration performance of the aerogels were studied. The results show that the 3DOM structure can effectively increase the micropore surface area of silver-silica aerogel, avoid the agglomeration and grain growth of active components silver, and significantly improve the iodine capture capacity. It will lay the foundation for the application of this new material in the capture of radioactive iodine in the future.

Transition metal modified 3DOM WO3 with activated N N bond triggering high-efficiency nitrogen photoreduction

Photocatalytic nitrogen fixation is a promising green strategy for ammonia synthesis, yet the high activation energy for nitrogen is the significant limitation to its practical application. Herein, a novel Fe-doped WO3 photocatalyst with three dimensional macroporous (3DOM) structure was designed and prepared. This special photocatalyst not only provides effective adsorption active sites to enhance the chemisorption and activation of N2, but also promotes the charge separation and transfer from catalyst to nitrogen. As a result, the optimized 5% Fe-3DOM WO3 sample achieves excellent ammonia production rate of 60 μmol g−1h−1, ∼30 times higher than that of pure 3DOM WO3. The in-situ DRIFTS results show the existence of several intermediates containing NH bonds during nitrogen reduction. Meanwhile, the density functional theory calculation results show that the presence of Fe promotes the adsorption and activation of nitrogen, and the reaction pathway is biased towards the alternate hydrogenation mechanism.