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Fluorescent photonic crystals (FPCs) are ideal candidates for regulating dyes’ fluorescence through their unique photonic band gaps (PBGs). However, challenges, including the lack of dynamic regulation of fluorescence, dye release in solvents, and instability, dramatically limit their practical applications. Here, we report mechanochromic and solvomechanochromic rhodamine B (RhB)-based FPCs with dynamic regulation of photoluminescence (PL) by stretching and swelling, brilliant fluorescent and structural colors, and no release of the RhB in solvents. The FPCs with force/solvent-responsive nonclose-packing structures were fabricated by (1) preparing RhB-silica particles by combining click chemistry and cohydrolysis processes and (2) self-assembling these particles in poly(ethylene glycol) phenyl ether acrylate followed by a photopolymerization. Maximal PL inhibition (37%, stretching strain of 6.8%) and enhancement (150%, swelling time of 8 min) were gained when PBGs and their blue edges are precisely adjusted to the PL peak position, respectively. Compared with stretching, PL regulation is more efficient by swelling. These characteristics benefit from the rational design and combination of unique compositions, chemical bonds, nonclosely packed micro/nanostructures, and solvents for swelling. Moreover, these FPCs have been used to encrypt photonic patterns, which display background/strain/angle/UV-dependent color contrasts, showing their potential applications in multilevel anticounterfeiting, optical devices, wireless sensors, etc.

Retroreflective structural colors can usually be achieved based on interference combined with a total internal reflection mechanism or diffraction of a monolayer hexagonal two-dimensional (2D) colloidal array. Here, a novel retroreflective structural color was generated based on a hexagonal–parallelogram lattice transformation by stretching 3D photonic crystals with nonclosely packed long-range order. Compared to previous retroreflective colors, this new retroreflective color exhibits two unique off/on color switches: (1) a strain-dependent off/on color switch along the stretching direction and (2) a sample horizontal rotation angle-dependent off/on color switch under the fixed strain. These strain-responsive retroreflective colors are ideal candidates for visually sensing kinesio tapes’ strain in practical applications and anticounterfeiting. This work reveals a new structural color regulation mechanism and will advance potential applications in anticounterfeiting, sensing, displays, etc.

Stimulus-responsive photonic crystals (PCs) possessing unconventional nonclosely packed structures have received growing attention due to their unique capability of mimicking the active structural colors of natural organisms (for example, chameleons’ mechanochromic properties). However, there is rarely any systematic review regarding the progress of nonclose-packed photonic crystals (NPCs), involving their fabrication, working mechanisms, and applications. Herein, a comprehensive review of the fundamental principles and practical fabrication strategies of one/two/three-dimensional NPCs is summarized from the perspective of designing nonclose-packed structures. Subsequently, responsive NPCs with exciting functions and working mechanisms are sorted and delineated according to their diverse responses to physical (force, temperature, magnetic, and electric fields), chemical (ions, pH, vapors, and solvents), and biological (glucose, organophosphate, creatinine, and bacteria) stimuli. We then systematically introduced and discussed the applications of NPCs in sensors, printing, anticounterfeiting, display, optical devices, etc.Finally, the current challenges and development prospects for NPCs are presented. This review not only concludes the design principle for NPCs but also provides a significant basis for the exploration of next-generation NPCs.

• WO 3 /TpPa-1-COF is synthesized through an in-situ growth approach. • Internal electric field drives the charge carrier diffusion in S-scheme mode. • WO 3 /TpPa-1-COF has strong redox abilities and high charge separation efficiency. • WO 3 /TpPa-1-COF display superior photocatalytic H 2 generation performance. The rapid charge recombination and low surface reaction kinetics are the two major constraints to the photocatalytic performance of covalent organic frameworks (COFs). To accelerate the charge separation behavior, TpPa-1-COF is decorated with WO 3 via an in-situ growth approach, and the resultant WO 3 /TpPa-1-COF composites show significantly improved photocatalytic performance. Especially, when the WO 3 loading arrives at 3 wt%, 3%WO 3 /TpPa-1-COF exhibits the maximum photocatalytic H 2 evolution rate of 19.89 mmol g−1 h−1, which is approximately 4.8 times higher than that of pure TpPa-1-COF. The apparent quantum efficiency (AQE) of 3%WO 3 /TpPa-1-COF at 420 nm is detected to be 12.4%. X-ray photoelectron spectroscopy (XPS) characterization confirms the formation of internal electric field between WO 3 and TpPa-1-CF, which can drive the photogenerated charge carrier diffusion in S-scheme mode. As a result, WO 3 /TpPa-1-COF composite possesses high charge separation efficiency and strong redox ability, which is further supported by the photoelectrochemical results, thus benefiting the photocatalysis process. This work provides a rational strategy to modify COFs in photocatalytic water splitting. [Display omitted] [ABSTRACT FROM AUTHOR]

Precise and efficient detection of solvents with similar refractive index is highly desired but remains a big challenge for the conventional opal because the shift of its reflection wavelength only depends on the refractive index of the solvent to be detected. Here, homologues (alcohols, acids, alkalis, esters, and aromatic hydrocarbons), isomers, and other solvents with similar refractive index and structures were precisely distinguished through the dynamic swelling reflection spectrum (DSRS) pattern based on the different swelling behavior of swellable photonic paper in solvents. The one reflection signal of photonic paper will split into two reflection peaks, which then tend to merge together during the swelling process. The variation of the reflection signals and merging time are highly sensitive to the polarity and refractive index of the solvent, and the differences can be significantly amplified in DSRS, resulting in the distinction of the solvent from its unique geometric pattern. Moreover, the variation tendency of the reflectance provides an additional parameter in recognition of the solvent, which can be explained by calculation and comparison of the practical volume ratio of the solvent swelled into the photonic paper and the corresponding critical volume ratio of the solvent determined by its refractive index.

Knowledge of the catalytic performances of different crystalline phases of a material is vital for the development of superior catalysts. In this study, different phases of MnO2(α, β, γ, and δ) have been prepared by the oxidation of Mn2+, and their catalytic performances were evaluated using the aerobic oxidation of benzyl alcohol to benzaldehyde as a model reaction. α-MnO2promoted the reaction to the highest yield. However, when the yields were normalized by the corresponding surface areas, δ-MnO2exhibited the highest specific activity and α-MnO2the lowest, indicating that the diverse microstructures resulting from the crystalline phase have a profound effect on catalytic performance. α-MnO2showed the highest catalytic stability, resulting from its unchanged composition and morphology after use. Informed by the experimental results, a possible reaction mechanism involving the Mars-van Krevelen process was proposed. This work provides useful information for the development of effective catalysts for aerobic oxidation. 研究同种物质不同晶相材料的催化性能对于遴选最佳的催化剂十分重要. 本文利用Mn2+的氧化反应制备了高纯度的不同晶相MnO2(α, β, γ, δ相), 通过苯甲醇耗氧氧化成苯甲醛的反应对其催化性能进行了评估. 结果显示, 在相同条件下, α-MnO2催化该反应的产率最高.如果用表面积归一化产率, 则δ-MnO2具有最高的面积比活性, 而α-MnO2的却最低. 不同晶相导致的不同微观结构决定了它们的催化性能. 经过多次催化反应后, 只有α-MnO2的成分和形貌均未改变, 显示出最高的催化稳定性. 因此提出了一种基于Mars-van Krevelen过程的可能的反应机理. 此工作可为发展有效的耗氧氧化反应催化剂提供有利支持.

a series of different substituents-modified C2v-symmetric cobaltoporphyrin complexes have been designed, synthesized and applied as efficient catalysts in conjunction with tetrabutylammonium iodide (TBAI) for the cycloaddition of epoxides and carbon dioxide. The porphyrin skeleton architectures with steric and electronic variation would deeply affect their catalytic performance. [5,15-Di(4-methoxyphenyl)porphyrin]cobalt(III) chloride (c-1) is the most effective catalyst under optimal reaction conditions. Foundational kinetic study results catalyzed by catalysts c-1, c-2, c-3and c-4reveal that the catalytic performance of electron-donating group-modified cobaltoporphyrin is better than it of electron-withdrawing group-modified ones, and high steric hindrance has a minor negative impact to its catalytic performance.

Self-assembled three-dimensional (3D) hierarchical umbilicate Bi2WO6microspheres from nanoplates have been synthesized by a new controllable hydrothermal route on a large scale. It was found that citrate played multifold roles in the formation process of Bi2WO6hierarchical microspheres in our reaction system. In order to obtain well-assembled Bi2WO6microspheres, NaHCO3was used to adjust pH values of the reaction solution and establish a buffer system by the equilibrium of the formation and dissociation of carbonic acid. On the basis of XRD analysis and TEM observation of the products at the different reaction time periods, the formation mechanism of Bi2WO6hierarchical microspheres was proposed. UV−vis diffuse reflectance spectra indicated that as-synthesized Bi2WO6hierarchical microspheres had absorption in both UV and visible light areas. The BET surface area of the sample was ca. 24.1 m2/g, which was 35 times higher than that of the Bi2WO6powder prepared by the solid-state reaction method. The hierarchical umbilicate Bi2WO6microspheres exhibited good photocatalytic activity in degradation of Rhodamine-B (RhB) under 150 W Xe lamp light irradiation. In addition, the wettability of Bi2WO6films fabricated by as-obtained Bi2WO6microspheres was also studied.

Hexagonal V0.13Mo0.87O2.935nanowires were hydrothermally synthesized at 220 °C for the first time. X-ray diffraction and field-emission scanning electron microscopy were utilized to characterize the phase and morphology of the nanowires, respectively. Transmission electron microscopy and selected area electron diffraction indicate that the nanowires are single crystalline, growing along the 001 direction. Interestingly, the nanowires easily become amorphous under the electron irradiation. The comparative hydrothermal experiments show that the molar ratio between the starting reagents of Mo and NH4VO3plays a vital role in the anisotropic growth of nanowires. The photoluminescence measurement demonstrates that these nanowires exhibit two strong emission peaks at 420 and 438 nm, which are probably related to the intrinsic oxygen vacancies.

This paper describes a surfactant-assisted hydrothermal reduction pathway toward various kinds of antimony and bismuth three-dimensional superstructures, containing hollow spheres composed of nanostrips, peony-like architecture, radial sub-micrometer rod bundles, and a shale-like pattern. These three-dimensional superstructures were obtained through the reduction of SbCl3 or Bi(NO3)35H2O by aluminum powder in different emulsion systems at 120C. The formation mechanism for Sb three-dimensional superstructures has been formally proposed. Some influencing factors on the morphology of the final products have also been discussed. We expect this convenient method can be extended to prepare three-dimensional superstructures of other inorganic materials, which have similar layered structures to Sb and Bi.

The skins of chameleons have attracted growing interest because they have sensitive mechano-chromic properties and bright colors due to the large surface-to-surface distances (Ds–s) between neighboring particles and contrast of the refractive index (Δn), respectively. Inspired by these, artificial mechano-chromic photonic skins (MPSs) mimicking those of chameleons were fabricated by the large Δnand Ds–s. The fabrication is considerably simple and efficient based on the self-assembly strategy using commercial chemicals and materials. The reflectance of MPSs depends on the value of Δn, which can be greatly increased to 70% with a Δnof 0.035, leading to their brilliant colors. Because of the large Ds–s, the MPSs possess outstanding mechano-chromic performances, including a large maximal (Δλ = 205 nm) and effective (Δλe= 184 nm) tuning range of the reflection wavelength, high sensitivity (368), fast responsiveness (2.2 nm/ms), good stabilities (>1 year), and reversibility (>100 times). Based on these advantages, MPSs have been used for self-reporting the strain of earthworms by outputting diverse colors during the peristaltic process, indicating the great potential of the MPSs as visual sensors and optical coatings.

Crystalline Eu(TTA)3phen (TTA is the conjugated base of 2-thenoyltrifluoroacetone, phen represents 1,10-phenanthroline) nanobelts were first prepared by solution-phase self-assembly. It was found that the concentration of Eu(TTA)3phen and solvent could impose obvious effect on the morphologies of the resultant products. The as-prepared crystalline Eu(TTA)3phen nanobelts show enhanced photoluminescence (PL) intensity over that of Eu(TTA)3phen molecules dissolved in tetrahydrofuran (THF) at the same concentration.

Self-assembled three-dimensional (3D) hierarchical BiVO4microspheres from nanoplates have been first synthesized by a facile malic acid-assisted hydrothermal route on a large scale. In the present hydrothermal system, malic acid played key roles in controlling the morphology and quality of the resultant products. The as-synthesized 3D hierarchical BiVO4microspheres exhibited good photocatalytic activity in degradation of Rhodamine B (RhB) under Xe-lamp light irradiation.

A new surfactant-assisted hydrothermal route was presented to prepare organometallic tris(8-hydroxyquinoline)aluminum nanorod bundles on a large scale. In this hydrothermal system, sodium dodecylbenzenesulfonate (Chemical formula: C12H25–C6H4–SO3Na, SDBS) played key roles in controlling the morphology and quality of the resultant products. The as-prepared nanorod bundles showed enhanced PL emission compared to submicron particles prepared by the same hydrothermal method.

In this letter a new synthetic strategy has been established for MoO3nanobelts by oxidizing Mo powders with H2O2in neutral water at 70 °C and a subsequent hydrothermal treatment at 140 °C. By introducing alcohol into this system, we can selectively prepare blue HxMoO3nanobelts. The photoluminescence (PL) property can be greatly altered before and after hydrogen incorporation into MoO3nanobelts. The mechanism on formation process of nanobelts has also been addressed.

Tellurium fibers are first synthesized through the reduction of Na2TeO4by hydrazine hydrate. The as-prepared tellurium fibers are used as templates for further reaction with aqueous AgNO3solution to get Ag2Te fibers at room temperature.

A novel solvothermal route combined with calcination was successfully established to synthesize octahedral In2O3particles, which exhibit near band emission. Interesting shape transformation from amorphous sphere to well-shaped octahedron was found.

A simple method was used to prepare carbon hollow spheres with average size of about 400 nm in diameter from metal zinc powder and ethanol. The FE-SEM and TEM images show that these carbon spheres have a ball-like and vessel-like morphology, all of which have smooth surfaces and a quite uniform diameter.