Single-crystalline α-Fe2O3 oblique nanoparallelepipeds: high-yield synthesis, growth mechanism and structure enhanced gas-sensing properties

Morphologies and magnetic properties of α-Fe2O3 nanoparticles calcined at different temperatures

Different morphologies and sizes of α-Fe2O3 were prepared by a coprecipitation method using polyvinylpyrrolidone as a dispersant. In the preparation process, homogeneous and dispersed nanoscale FeOOH particles were first obtained by the coprecipitation method, and then the FeOOH particles were calcined at high temperature to form α-Fe2O3. The growth and aggregation of the α-Fe2O3 particles at different calcination temperatures resulted in α-Fe2O3 powders with diversiform morphologies (nanoscale microsphere, pinecone ellipsoidal, polyhedral, and quasi-spherical structures). By analyzing the SEM images, it was inferred that the polyhedral structure of α-Fe2O3 particles was formed by the accumulation of rhomboid sheet structures and high-temperature growth. In terms of the magnetic properties, the samples belonged to the class of canted antiferromagnetic materials, and the morphology, particle size, and crystallite size of the α-Fe2O3 particles were important factors affecting the coercivity. Among these, when the calcination temperature was increased from 700 °C to 800 °C, the growth rate of the particle size was significantly faster than that of the crystallite size, and the coercivity increased substantially from 1411 Oe to 2688 Oe.

Utilizing Undissolved Portion (UNP) of Cement Kiln Dust as a Versatile Multicomponent Catalyst for Bioethylene Production from Bioethanol: An Innovative Approach to Address the Energy Crisis

This study focuses on upcycling cement kiln dust (CKD) as an industrial waste by utilizing the undissolved portion (UNP) as a multicomponent catalyst for bioethylene production from bioethanol, offering an environmentally sustainable solution. To maximize UNP utilization, CKD was dissolved in nitric acid, followed by calcination at 500 °C for 3 h in an oxygen atmosphere. Various characterization techniques confirmed that UNP comprises five different compounds with nanocrystalline particles exhibiting an average crystal size of 47.53 nm. The UNP catalyst exhibited a promising bioethylene yield (77.1%) and selectivity (92%) at 400 °C, showcasing its effectiveness in converting bioethanol to bioethylene with outstanding properties. This exceptional performance can be attributed to its distinctive structural characteristics, including a high surface area and multiple-strength acidic sites that facilitate the reaction mechanism. Moreover, the UNP catalyst displayed remarkable stability and durability, positioning it as a strong candidate for industrial applications in bioethylene production. This research underscores the importance of waste reduction in the cement industry and offers a sustainable path toward a greener future.

3D Hierarchically Structured Tin Oxide and Iron Oxide-Embedded Carbon Nanofiber with Outermost Polypyrrole Layer for High-Performance Asymmetric Supercapacitor

Herein, unique three-dimensional (3D) hierarchically structured carbon nanofiber (CNF)/metal oxide/conducting polymer composite materials were successfully synthesized by combinations of various experimental methods. Firstly, base CNFs were synthesized by carbonization of electrospun PAN/PVP fibers to attain electric double-layer capacitor (EDLC) characteristics. To further enhance the capacitance, tin oxide (SnO₂) and iron oxide (Fe₂O₃) were coated onto the CNFs via facile hydrothermal treatment. Finally, polypyrrole (PPy) was introduced as the outermost layer by a dispersion polymerization method under static condition to obtain 3D-structured CNF/SnO₂/PPy and CNF/Fe₂O₃/PPy materials. With each synthesis step, the morphology and dimension of materials were transformed, which also added the benign characteristic for supercapacitor application. For the practical application, as-synthesized CNF/SnO₂/PPy and CNF/Fe₂O₃/PPy were applied as active materials for supercapacitor electrodes, and superb specific capacitances of 508.1 and 426.8 F g^-1 (at 1 A g^-1) were obtained (three-electrode system). Furthermore, an asymmetric supercapacitor (ASC) device was assembled using CNF/SnO₂/PPy as the positive electrode and CNF/Fe₂O₃/PPy as the negative electrode. The resulting CNF/SnO₂/PPy//CNF/Fe₂O₃/PPy device exhibited excellent specific capacitance of 101.2 F g^-1 (at 1 A g^-1). Notably, the ASC device displayed a long-term cyclability (at 2000 cycles) with a retention rate of 81.1%, compared to a CNF/SnO₂//CNF/Fe₂O₃ device of 70.3% without an outermost PPy layer. By introducing the outermost PPy layer, metal oxide detachment from CNFs were prevented to facilitate long-term cyclability of electrodes. Accordingly, this study provides an effective method for manufacturing a high-performance and stable supercapacitor by utilizing unique 3D hierarchical materials, comprised of CNF, metal oxide, and conducting polymer.

A dimethyl disulfide gas sensor based on nanosized Pt-loaded tetrakaidecahedralα-Fe2O3nanocrystals

Surface modification by employing precious metals is one of the most effective ways to improve the gas-sensing performance of metal oxide semiconductors. Pureα-Fe₂O₃nanoparticles and Pt-modifiedα-Fe₂O₃nanoparticles were prepared sequentially using a rather simple hydrothermal synthesis and impregnation method. Compared with the originalα-Fe₂O₃nanomaterials, the Pt-α-Fe₂O₃nanocomposite sensor shows a higher response value (R_a/R_g = 58.6) and a shorter response/recovery time (1 s/168 s) to 100 ppm dimethyl disulfide (DMDS) gas at 375 °C. In addition, it has better selectivity to DMDS gas with the value of more than 9 times higher than the other target gases at 375 °C. This study indicates that the Pt-α-Fe₂O₃nanoparticle sensor has good prospects and can be used as a low-cost and effective DMDS gas sensor.

Improving the CO and CH4 Gas Sensor Response at Room Temperature of α-Fe2O3(0001) Epitaxial Thin Films Grown on SrTiO3(111) Incorporating Au(111) Islands

In this work, the functional character of complex α-Fe2O3(0001)/SrTiO3(111) and Au(111) islands/α-Fe2O3(0001)/SrTiO3(111) heterostructures has been proven as gas sensors at room temperature. Epitaxial Au islands and α-Fe2O3 thin film are grown by pulsed laser deposition on SrTiO3(111) substrates. Intrinsic parameters such as the composition, particle size and epitaxial character are investigated for their influence on the gas sensing response. Both Au and α-Fe2O3 layer show an island-type growth with an average particle size of 40 and 62 nm, respectively. The epitaxial and incommensurate growth is evidenced, confirming a rotation of 30° between the in-plane crystallographic axes of α-Fe2O3(0001) structure and those of SrTiO3(111) substrate and between the in-plane crystallographic axes of Au(111) and those of α-Fe2O3(0001) structure. α-Fe2O3 is the only phase of iron oxide identified before and after its functionalization with Au nanoparticles. In addition, its structural characteristics are also preserved after Au deposition, with minor changes at short-range order. Conductance measurements of Au(111)/α-Fe2O3(0001)/SrTiO3(111) system show that the incorporation of epitaxial Au islands on top of the α-Fe2O3(0001) layer induces an enhancement of the gas-sensing activity of around 25% under CO and 35% under CH4 gas exposure, in comparison to a bare α-Fe2O3(0001) layer grown on SrTiO3(111) substrates. In addition, the response of the heterostructures to CO gas exposure is around 5–10% higher than to CH4 gas in each case.

Y-doped In2O3 hollow nanocubes for improved triethylamine-sensing performance

Y-In₂O₃ hollow nanocubes show enhanced triethylamine gas sensing properties, with a high response and an ultra-fast response-recovery speed.

Toward Informed Design of Nanomaterials: A Mechanistic Analysis of Structure-Property-Function Relationships for Faceted Nanoscale Metal Oxides

Nanoscale metal oxides (NMOs) have found wide-scale applicability in a variety of environmental fields, particularly catalysis, gas sensing, and sorption. Facet engineering, or controlled exposure of a particular crystal plane, has been established as an advantageous approach to enabling enhanced functionality of NMOs. However, the underlying mechanisms that give rise to this improved performance are often not systematically examined, leading to an insufficient understanding of NMO facet reactivity. This critical review details the unique electronic and structural characteristics of commonly studied NMO facets and further correlates these characteristics to the principal mechanisms that govern performance in various catalytic, gas sensing, and contaminant removal applications. General trends of facet-dependent behavior are established for each of the NMO compositions, and selected case studies for extensions of facet-dependent behavior, such as mixed metals, mixed-metal oxides, and mixed facets, are discussed. Key conclusions about facet reactivity, confounding variables that tend to obfuscate them, and opportunities to deepen structure-property-function understanding are detailed to encourage rational, informed design of NMOs for the intended application.

Volatile Organic Compound Gas-Sensing Properties of Bimodal Porous α-Fe2O3 with Ultrahigh Sensitivity and Fast Response

Porous solid with multimodal pore size distribution provides plenty of advantages including large specific surface area and superior mass transportation to achieve high gas-sensing performances. In this study, α-Fe₂O₃ nanoparticles with bimodal porous structures were prepared successfully through a nanocasting pathway, adopting the bicontinuous 3D cubic symmetry mesoporous silica KIT-6 as the hard template. Its structure and morphology were characterized by X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscopy, and so on. Furthermore, the gas sensor fabricated from this material exhibited excellent gas-sensing performance to several volatile organic compounds (acetone, ethyl acetate, isopropyl alcohol, n-butanol, ethanol, and methanol), such as ultrahigh sensitivity, rapid response speed (less than 10 s) and recovery time, good reproducibility, as well as stability. These would be associated with the desirable pore structure of the material, facilitating the molecules diffusion toward the entire sensing surface, and providing more active sensing sites for analytical gas.

Room-Temperature Ammonia Gas Sensing Using Mixed-Valent CuCo2O4 Nanoplatelets: Performance Enhancement through Stoichiometry Control

We report the sensing properties of an interesting ternary oxide CuCo₂O₄ (CCO) which comprises two earth-abundant transition elements, both capable of supporting multiple valence states. We have used a synthesis protocol, which renders unique nanoplatelet-type morphology but with a degree of biphasic character (CuO as a secondary phase in addition to the defect-spinel Cu_1-x Co₂O₄). This sample constitution can be controlled through the use of cation off-stoichiometry, and the same also influence the sensing response significantly. In particular, a Co 10 at. % excess CCO (CCO-Co(10)) case exhibits a good response (∼7.9% at 400 ppm) for NH₃ gas with a complete recovery at room temperature (23 °C, ±1 °C) in 57% RH. The material performance was investigated for other gases such as H₂S, NO₂, and CO. A good response is observed for H₂S and NO₂ gases but without a recovery; however, for CO, a poor response is noted. Herein, we discuss the specific results for ammonia sensing for the CCO-Co(10) case in detail via the use of different characterizations and outline the difference between the cases of the single-phase defect-stabilized material versus nonpercolating biphasic material.

Understanding the facet-dependent catalytic performance of hematite microcrystals in a CO oxidation reaction

α-Fe₂O₃ microcrystals with uniform plate, cube and rod morphologies have been synthesized. DFT calculations and experimental results indicated that the Fe₂O₃ nanorods showed an obvious improvement of CO catalytic activities due to their unique surface structure.

Enhanced Gas Sensitivity and Sensing Mechanism of Network Structures Assembled from α-Fe2O3 Nanosheets with Exposed {104} Facets

Network structures assembled from α-Fe₂O₃ nanosheets with exposed {104} facets were successfully prepared by heating Fe(NO₃)₃ solution containing polyvinylpyrrolidone (PVP) in air. The α-Fe₂O₃ nanosheet-based network structures demonstrate significantly higher response to ethanol and triethylamine than α-Fe₂O₃ commercial powders. The excellent sensing performances can be ascribed to the exposed (104) facet terminated with Fe atoms. A concept of the unsaturated Fe atoms serving as the sensing reaction active sites is thus proposed, and the sensing reaction mechanism is described at the atomic and molecular level for the first time in detail. The concept of the surface metal atoms with dangling bonds serving as active sites can deepen understanding of the sensing and other catalytic reaction mechanisms and provides new insight into the design and fabrication of highly efficient sensing materials, catalysts, and photoelectronic devices.

Nanostructured Materials for Room-Temperature Gas Sensors

Sensor technology has an important effect on many aspects in our society, and has gained much progress, propelled by the development of nanoscience and nanotechnology. Current research efforts are directed toward developing high-performance gas sensors with low operating temperature at low fabrication costs. A gas sensor working at room temperature is very appealing as it provides very low power consumption and does not require a heater for high-temperature operation, and hence simplifies the fabrication of sensor devices and reduces the operating cost. Nanostructured materials are at the core of the development of any room-temperature sensing platform. The most important advances with regard to fundamental research, sensing mechanisms, and application of nanostructured materials for room-temperature conductometric sensor devices are reviewed here. Particular emphasis is given to the relation between the nanostructure and sensor properties in an attempt to address structure-property correlations. Finally, some future research perspectives and new challenges that the field of room-temperature sensors will have to address are also discussed.

Morphology evolution of single-crystalline hematite nanocrystals: magnetically recoverable nanocatalysts for enhanced facet-driven photoredox activity

We have developed a new green chemical approach for the shape-controlled synthesis of single-crystalline hematite nanocrystals in aqueous medium. FESEM, HRTEM and SAED techniques were used to determine the morphology and crystallographic orientations of each nanocrystal and its exposed facets. PXRD and HRTEM techniques revealed that the nanocrystals are single crystalline in nature; twins and stacking faults were not detected in these nanocrystals. The structural, vibrational, and electronic spectra of these nanocrystals were highly dependent on their shape. Different shaped hematite nanocrystals with distinct crystallographic planes have been synthesized under similar reaction conditions, which can be desired as a model for the purpose of properties comparison with the nanocrystals prepared under different reaction conditions. Here we investigated the photocatalytic performance of these different shaped-nanocrystals for methyl orange degradation in the presence of white light (λ > 420 nm). In this study, we found that the density of surface Fe(3+) ions in particular facets was the key factor for the photocatalytic activity and was higher on the bitruncated-dodecahedron shape nanocrystals by coexposed {104}, {100} and {001} facets, attributing to higher catalytic activity. The catalytic activity of different exposed facet nanocrystals were as follows: {104} + {100} + {001} (bitruncated-dodecahedron) > {101} + {001} (bitruncated-octahedron) > {001} + {110} (nanorods) > {012} (nanocuboid) which provided the direct evidence of exposed facet-driven photocatalytic activity. The nanocrystals were easily recoverable using an external magnet and reused at least six times without significant loss of its catalytic activity.

Hierarchical growth of ZnFe2O4 for sensing applications

Selective sensing of toxic heavy metals Hg(ii) and environmentally hazardous acetone vapour using mesoporous ZnFe₂O₄ NFs, synthesized from our laboratory developed modified hydrothermal technique.

Adsorption and gas-sensing characteristics of a stoichiometric α-Fe2O3 (0 0 1) nano thin film for carbon dioxide and carbon monoxide with and without pre-adsorbed O2

The opposite behaviors of charge transformation for CO₂ and CO molecules adsorbed on an α-Fe₂O₃ (0 0 1) nano thin film with and without pre-adsorbed O₂.

A high-performance dual-function material: self-assembled super long α-Fe2O3 hollow tubes with multiple heteroatom (C-, N- and S-) doping

Flow diagram of the synthesis of nitrogen doped α-Fe₂O₃ nanorods into super long hollow tubes.

Shape-controlled iron oxide nanocrystals: synthesis, magnetic properties and energy conversion applications

Iron oxide nanocrystals (IONCs) with various geometric morphologies show excellent physical and chemical properties and have received extensive attention in recent years.

Ethanol Gas Detection Using a Yolk-Shell (Core-Shell) α-Fe2O3 Nanospheres as Sensing Material

Three-dimensional (3D) nanostructures of α-Fe2O3 materials, including both hollow sphere-shaped and yolk-shell (core-shell)-shaped, have been successfully synthesized via an environmentally friendly hydrothermal approach. By expertly adjusting the reaction time, the solid, hollow, and yolk-shell shaped α-Fe2O3 can be selectively synthesized. Yolk-shell α-Fe2O3 nanospheres display outer diameters of 350 nm, and the interstitial hollow spaces layer is intimately sandwiched between the inner and outer shell of α-Fe2O3 nanostructures. The possible growth mechanism of the yolk-shell nanostructure is proposed. The results showed that the well-defined bilayer interface effectively enhanced the sensing performance of the α-Fe2O3 nanostructures (i.e., yolk-shell α-Fe2O3@α-Fe2O3), owing predominantly to the unique nanostructure, thus facilitated the transport rate and augmented the adsorption quantity of the target gas molecule under gas detection.

Template-free construction of hollow α-Fe2O3 hexagonal nanocolumn particles with an exposed special surface for advanced gas sensing properties

Hollow α-Fe2O3 hexagonal nanocolumn particles (HHCPs) with exposed (101[combining macron]0) and (112[combining macron]5) facets have been synthesized through a hydrothermal method in the absence of templates. The time-dependent experimental results demonstrate that the formation of HHCPs includes four main steps: (1) formation of nanowire precursors, (2) aggregation and conversion to Fe1.833(OH)0.5O2 solid ellipsoid particles (SEPs), (3) dehydration to form hollow ellipsoid particles (HEPs), and (4) recrystallization to HHCPs. Due to their advantages of the hollow structure and the exposed special external and internal surface on the pore structure, the HHCPs exhibit higher gas sensing ability than that of calcined SEPs (CSEPs) and HEPs.

Ferric Phosphate Hydroxide Microstructures Affect Their Magnetic Properties

Uniformly sized and shape-controlled nanoparticles are important due to their applications in catalysis, electrochemistry, ion exchange, molecular adsorption, and electronics. Several ferric phosphate hydroxide (Fe4(OH)3(PO4)3) microstructures were successfully prepared under hydrothermal conditions. Using controlled variations in the reaction conditions, such as reaction time, temperature, and amount of hexadecyltrimethylammonium bromide (CTAB), the crystals can be grown as almost perfect hyperbranched microcrystals at 180 °C (without CTAB) or relatively monodisperse particles at 220 °C (with CTAB). The large hyperbranched structure of Fe4(OH)3(PO4)3 with a size of ∼19 μm forms with the "fractal growth rule" and shows many branches. More importantly, the magnetic properties of these materials are directly correlated to their size and micro/nanostructure morphology. Interestingly, the blocking temperature (T B) shows a dependence on size and shape, and a smaller size resulted in a lower T B. These crystals are good examples that prove that physical and chemical properties of nano/microstructured materials are related to their structures, and the precise control of the morphology of such functional materials could allow for the control of their performance.

Aerosol-spray diverse mesoporous metal oxides from metal nitrates

Transition metal oxides are widely used in solar cells, batteries, transistors, memories, transparent conductive electrodes, photocatalysts, gas sensors, supercapacitors, and smart windows. In many of these applications, large surface areas and pore volumes can enhance molecular adsorption, facilitate ion transfer, and increase interfacial areas; the formation of complex oxides (mixed, doped, multimetallic oxides and oxide-based hybrids) can alter electronic band structures, modify/enhance charge carrier concentrations/separation, and introduce desired functionalities. A general synthetic approach to diverse mesoporous metal oxides is therefore very attractive. Here we describe a powerful aerosol-spray method for synthesizing various mesoporous metal oxides from low-cost nitrate salts. During spray, thermal heating of precursor droplets drives solvent evaporation and induces surfactant-directed formation of mesostructures, nitrate decomposition and oxide cross-linking. Thirteen types of monometallic oxides and four groups of complex ones are successfully produced, with mesoporous iron oxide microspheres demonstrated for photocatalytic oxygen evolution and gas sensing with superior performances.

An ultraselective and ultrasensitive TEA sensor based on α-MoO3 hierarchical nanostructures and the sensing mechanism

Flower-like α-MoO₃ hierarchical nanostructures were successfully synthesized via a single-step solvothermal route. A sensor based on α-MoO₃ flowers manifested superior gas sensing performance towards TEA at 170 °C.

Metal oxides and metal salt nanostructures for hydrogen sulfide sensing: mechanism and sensing performance

Metal oxides and metal salt nanostructures for hydrogen sulfide sensing based on conductivity response.

An old workhorse for new applications: Fe(dpm)3 as a precursor for low-temperature PECVD of iron(iii) oxide

A combined theoretical–experimental investigation on Fe(dpm)₃ as a precursor for PECVD of iron(iii) oxide is presented. Pure Fe₂O₃ nanomaterials have been obtained at temperatures as low as 100 °C, even on flexible plastic substrates.

Diethylenetriamine-assisted hydrothermal synthesis of dodecahedral α-Fe2O3 nanocrystals with enhanced and stable photoelectrochemical activity

A facile diethylenetriamine-assisted protocol is developed to prepare dodecahedral α-Fe₂O₃ nanocrystals, which exhibit efficient photoelectrocatalytic water splitting activity.

Supersaturation-controlled shape evolution of α-Fe2O3 nanocrystals and their facet-dependent catalytic and sensing properties

Surface engineering of crystals at nanoscale level by precisely and rationally exposing specific facets proved to be highly effective in enhancing the performance of inorganic functional nanocrystals. To do so, a comprehensive understanding of the growth mechanism was of great importance. By using hematite (α-Fe2O3) as an example, in this paper we demonstrated high effectiveness of controlling supersaturation of growth monomers in engineering the exposed facets of nanocrystals. Under surfactant-free hydrothermal conditions, a series of morphology evolution of α-Fe2O3 nanocrystals from {012} faceted pseudocubes to {113} faceted hexagonal bipyramids and {001} faceted nanoplates were successfully activated through concentration-, reaction time-, and solvent-dependent hydrolysis of ferric acetylacetonate. High supersaturation was eventually proven to be conducive to the formation of facets with high surface energy. Furthermore, the α-Fe2O3 nanocrystals enclosed with facets of high surface energy exhibited excellent catalytic activity and gas-sensing ability. The present work will deepen our understanding of thermodynamics and kinetic control over the morphology of nanocrystals as well as our understanding of surface-related performance of inorganic functional nanocrystals.

Hematite concave nanocubes and their superior catalytic activity for low temperature CO oxidation

Hematite (α-Fe2O3) concave nanocubes bound by high-index {1344̄} and {123̄8} facets were synthesized and their catalytic activity for CO oxidation were also investigated.

Facile synthesis of single-crystalline hollow α-Fe2O3 nanospheres with gas sensing properties

High-quality single-crystalline hollow α-Fe₂O₃ nanospheres were prepared, using ZnS–CHA nanohybrid as additive with gas sensing property.

Rational design of interfacial properties of ferric (hydr)oxide nanoparticles by adsorption of fatty acids from aqueous solutions

Notwithstanding the great practical importance, still open are the questions how, why, and to what extent the size, morphology, and surface charge of metal (hydr)oxide nanoparticles (NPs) affect the adsorption form, adsorption strength, surface density, and packing order of organic (bio)molecules containing carboxylic groups. In this article, we conclusively answer these questions for a model system of ferric (hydr)oxide NPs and demonstrate applicability of the established relationships to manipulating their hydrophobicity and dispersibility. Employing in situ Fourier transform infrared (FTIR) spectroscopy and adsorption isotherm measurements, we study the interaction of 150, 38, and 9 nm hematite (α-Fe(2)O(3)) and ∼4 nm 2-line ferrihydrite with sodium laurate (dodecanoate) in water. We discover that, independent of morphology, an increase in size of the ferric (hydr)oxide NPs significantly improves their adsorption capacity and affinity toward fatty acids. This effect favors the formation of bilayers, which in turn promotes dispersibility of the larger NPs in water. At the same time, the local order in self-assembled monolayer (SAM) strongly depends on the morphological compatibility of the NP facets with the geometry-driven well-packed arrangements of the hydrocarbon chains as well as on the ratio of the chemisorbed to the physically adsorbed carboxylate groups. Surprisingly, the geometrical constraints can be removed, and adsorption capacity can be increased by negatively polarizing the NPs due to promotion of the outer-sphere complexes of the fatty acid. We interpret these findings and discuss their implications for the nanotechnological applications of surface-functionalized metal (hydr)oxide NPs.

Ni2+/surfactant-assisted route to porous α-Fe2O3 nanoarchitectures

Uniform porous three-dimensional nanoarchitectures of α-Fe(2)O(3) with high yield have been synthesized by a route based on a Ni(2+)/surfactant system. The obtained α-Fe(2)O(3) has a flue-like porous morphology with a rough surface. What is more, spatially ordered nodes and meshes are presented in these networks. By adjusting the experimental parameters such as temperature, reaction time, proportion of Ni(2+)/PVP and types of cation, we can control the morphology of the samples well. A possible formation mechanism is proposed to explain the growth of the flue-like nanostructures. The obtained flue-like porous α-Fe(2)O(3) has a large specific surface area of 88.82 m(2) g(-1). It exhibits significantly enhanced visible-light-driven photocatalytic performance in the degradation of methylene blue, compared with α-Fe(2)O(3) nanoparticles. This work not only enriches the synthesis methods of porous architectures, but also facilitates the applications of α-Fe(2)O(3) in the fields of water treatment, sunlight utilization and so forth.