Formation Of Hollow Structure Research Articles

Designing a highly near infrared-reflective black nanoparticles for autonomous driving based on the refractive index and principle

HypothesisThe development of highly NIR reflective black single-shell hollow nanoparticles (BSS-HNPs) can overcome the Light Detection and Ranging (LiDAR) sensor limitations of dark-tone materials. The crystalline phase of TiO2 and the refractive index can be controlled by calcination temperature. The formation of hollow structure and the refractive index is expected to simultaneously increase the light reflection and LiDAR detectability. ExperimentsThe BSS-HNPs are synthesized using the sol–gel method, calcination, NaBH4 reduction, and etching to form a hollow structure with true blackness. The computational bandgap calculation is conducted to determine the bandgap energy (Eg) of the white and black TiO2 with different crystalline structures. The blackness of the as-synthesized materials is determined by the Commission on Illumination (CIE) L*a*b* color system. FindingsThe hydrophilic nature of BSS-HNPs enables the formulation of hydrophilic paints, allowing the mono-layer coating. With the synergistic effects of hollow structure and the refractive index, BSS-HNPs manifested superb NIR reflectance at LiDAR detection wavelengths. The high detectability, blackness, and hollow structure of BSS-HNPs can expand the variety of LiDAR-detectable dark-tone materials.

Metal-organic-frameworks derived hollow carbon derivatives: Controllable configurations and optimized microwave absorption

Metal-organic-frameworks (MOFs) derivatives with diverse architectures and adjusted chemical compositions have been recognized as one of the promising candidates in the field of microwave absorption, especially carbon derivatives with hollow structure. Herein, the recent strategies in fabrication of hollow MOFs derivatives and the relationship between hollow structure and microwave absorption performance are briefly summarized. Then, the synthesized mechanism and crucial factors in the formation of hollow structure are systematically analyzed. Finally, the current challenges and future research trends are predicted, which provide guidelines for the regulation of hollow MOFs derivatives and the manipulation of microwave absorption performance.

Formation of Fe-doped ZrO2 nanotube arrays in glycerol/formamide at varying fluoride content for Cr(VI) photoreduction

Fe-doped ZrO2 nanotubes (Fe-ZNTs) were produced by anodizing a Zr-5 wt% Fe (Zr-5Fe) alloy in a mixture of fluoride-containing glycerol/formamide (FA) (1:1 ratio)/1 vol% H2O at 50 V for 3 h in different concentrations of ammonium fluoride (NH4F) (0.3, 0.5, and 1.0 wt%). These materials were synthesized to serve as photocatalysts for the removal of hexavalent chromium, Cr(VI) ions by photoreduction. To crystallize the oxide film, the as-anodized Fe-ZNTs were subjected to annealing at 500 ℃ for 3 h in a tube furnace. The morphology and crystal structure of the annealed Fe-ZNTs were analyzed using Field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively. The surface functional groups and surface chemical of the samples were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The formation of hollow structure of the Fe-ZNT was validated by High-resolution transmission electron microscopy (HRTEM). The dimensions of the Fe-ZNTs were measured using Image J. UV–Visible spectroscopy was used to determine the Cr(VI) concentration remaining in the sample after photoreduction. From the FESEM micrographs, the diameter of the Fe-ZNTs was enlarged with higher fluoride content, while the length abruptly decreased due to excessive etching of the oxide film at oxide|electrolyte interface. The XRD results indicate the high intensity of tetragonal-ZrO2 in high fluoride content after annealing. From the photocatalytic results of 30 ppm Cr(VI) under sunlight, the Fe-ZNTs synthesized in 1.0 wt% NH4F exhibited the highest Cr(VI) removal efficiency with 100 % after 5 h due to enhanced Cr(VI) adsorption and high photoactivity of tetragonal-ZrO2.

Interface and morphology engineering of Ru-FeCoP hollow nanocages as alkaline electrocatalyst for overall water splitting

Interface and Morphology engineering strategies of electrocatalysts are of great importance to promote water splitting performance, although still facing many challenges. In this work, we present a facile method for preparing Ru-anchored hollow FeCoP nanocages electrocatalyst with ultrathin sheets. The hollow structure composed of ultrathin nanosheets and rich heterogeneous interfaces benefit the as-synthesized catalyst to exhibit small overpotentials of 310 mV and 94 mV at the current density of 10 mA·cm−2 for oxygen evolution reaction and hydrogen evolution reaction, respectively. When Ru-FeCoP nanocages were employed as the bifunctional catalyst for overall water splitting, the potential of 1.65 V was obtained to reach the current density of 10 mA·cm−2. The experimental results confirmed that the formation of hierarchical hollow structure facilitated the exposure of active sites and enhanced the electrocatalytic activity. Meanwhile, XPS and DFT data also reveal that the presence of heterogeneous interfaces changed the electronic structure, optimized the absorption of the intermediates, significantly reduced the energy barrier of water dissociation and promoted the release of H2. This work offers an effective route for rational design of low-loading noble metal-anchored metal phosphide with the hierarchical hollow structure and rich interfaces towards overall water splitting.

Facile fabrication of hollow molecularly imprinted polymer microspheres via pickering emulsion polymerization stabilized with TiO2 nanoparticles

The polymer microspheres with hollow structure are of technological importance in the removal of pollutants because of the large specific surface area and low mass transfer resistance. In this work, we employ the Pickering emulsion polymerization stabilized with TiO2 nanoparticles to build the molecularly imprinted polymers microspheres with hollow structure (H-MIPs) for the precise recognition of dibutyl phthalate (DBP), which would influence the biological reproductive system and endocrine system as a typical endocrine disrupting compound. The polymerization induced phase separation occurring within Pickering emulsion droplets plays a significant role in the formation of hollow structure. The morphology and structure of H-MIPs were observed via optical microscope and field emission scanning electron microscope, respectively. The results indicate that H-MIPs microspheres are of irregular spherical form with sunken surface and perfect hollow structure. The forming process of the hollow structure was analyzed in detail. Besides, the chemical structure and thermal stability of H-MIPs and H-NIPs were characterized by fourier transform infrared spectroscopy and thermal gravimetric analysis, respectively. The binding performance of H-MIPs and H-NIPs was investigated through a series of binding experiments, which consist of the binding kinetics, binding isotherm, selective test and reusability experiment. The results show that H-MIPs microspheres exhibit remarkable binding kinetics towards DBP, and the saturated adsorption time is not more than 30 min. Apart from the fast binding rate, H-MIPs also show considerable binding amount, accurate binding selectivity and good regenerability. The imprinting factor could reach to 2.56, and the binding amount towards DBP remains at a relatively high level within 3 cycles. The prepared H-MIPs microspheres have broad application prospects in environmental and analytical field involved DBP, and the study also offers an alternative method for the facile building of H-MIPs microspheres.

Preparation and Characterization of Hollow CeO2 Nanoparticles for the Efficient Conversion of CO2 into Dimethyl Carbonate

AbstractThe hollow CeO2 (H‐CeO2) nanoparticles with mesoporous defects structure were prepared by a solid template method under ambient pressure and applied to catalyze the conversion of CO2 into dimethyl carbonate (DMC). The textural properties of H‐CeO2 were investigated by various characterization techniques. The results showed that H‐CeO2 have higher surface area, more mesoporous defects and higher surface oxygen vacancies concentration than those of conventional CeO2 with block morphology (C‐CeO2). Therefore, H‐CeO2 exhibited better catalytic performance for the conversion of CO2 into DMC. Additionally, the Ce(NO3)3 ⋅ 6H2O amount in preparation procedure was important for the formation of hollow structure and mesoporous defects. The DMC yield could reach 4.96 % on H‐CeO2‐1.2 (Ce(NO3)3 ⋅ 6H2O amount: 1.2 g) catalyst when the reaction was performed at 140 °C and 4.5 MPa for 4 h. This work proposed a facile strategy for designing CeO2 catalysts for the CO2 conversion by creating mesoporous defective structure.

PVP-assisted synthesis of hollow Ni0.75Zn0.25Fe2O4 nanospheres for lithium-ion batteries

Hollow Ni0.75Zn0.25Fe2O4 nanospheres with a diameter of about 250–300 nm and thickness of 30–40 nm have been successfully fabricated through a PVP (polyvinylpyrrolidone)-assisted hydrothermal strategy. PVP plays an important role in the formation of hollow structure and a plausible formation mechanism of hollow Ni0.75Zn0.25Fe2O4 nanospheres is also proposed in this paper. The as-fabricated hollow Ni0.75Zn0.25Fe2O4 nanospheres display a good dispersibility and high specific surface area of 34.7 m2 g−1. Hollow Ni0.75Zn0.25Fe2O4 nanospheres also demonstrate satisfactory cycle life and rate performance when evaluated as a lithium ion battery negative electrode. Namely, after 120 cycles, the discharge specific capacity is 1321.3 mAh g−1 at 200 mA g−1, and the capacity retention rate is as high as 99.2%. Furthermore, the average discharge capacities are 1482.5, 1451.5, 1330.9, 1232.3, 1031.2 and 944.8 mAh g−1 under the current densities of 100, 200, 500, 1000, 2000 and 4000 mA g−1, respectively. The promising electrochemical performance of the hollow Ni0.75Zn0.25Fe2O4 nanosphere could be attributed to the unique hollow structure of nanospheres, which offers a higher specific surface area and shorten transmission pathways of electrons and ions, buffering the volume expansion during the Li+ insertion/desorption process.

Facile synthesis of silica hollow microspheres as biocompatible cell carriers

Silica hollow microspheres were prepared by using the emulsified gelatin microspheres as novel sacrificial templates and then employed as biocompatible cell carriers. SEM observations show that they were spherical in morphology with a hollow structure and had a diameter of 50–200 µm. FT-IR spectrum reveals that they were rich in Si-O-Si bonds. It is found that gelatin microspheres served as supporting matrix and sacrificial templates responsible for the formation of hollow structure. By seeding the osteoblast MC3T3-E1 cells, each individual silica hollow microsphere was biocompatible and favored cell attachment and proliferation, indicating that they have potential as biocompatible cell carriers.

Rational regulation of peroxymonosulfate activation over porous Co3O4 with carbon coating to boost utilization efficiency of peroxymonosulfate and achieve rapid removal of pollutants

It is of great significance to regulate rationally the activation mechanism of persulfate for promoting the development of sulfate radical-based advanced oxidation processes in wastewater treatment. Herein, carbon coated porous Co3O4 with hollow structure was synthesized. Notably, the formation of porous hollow structure improved specific surface area of Co3O4 and offered more redox couples of Co2+/Co3+, thereby reducing electron transfer resistance. Thus, the generation of reactive oxygen species and the role of high-valent transition metal complexes (namely Co3O4Co4+) were improved. The formation of carbon layer on the Co3O4 surface can avoid the release of Co ion during reaction process. Benefiting from the role of carbon layer in electron transport, catalyst-mediated the direct electron transfer from pollutant to PMS was boosted. Radical and nonradical pathways worked in coordination each other and realized the rapid removal of various organic pollutants in the presence of a little PMS. In short, current work revealed that modulating rationally the microstructure of catalyst was an efficient strategy for achieving controllable regulation of PMS activation process. More significantly, whether the direct electron transfer process can occur or not depended on both catalyst structure and electronic density of pollutants.

Efficient and controllable synthesis of zeolite Beta nanospheres and hollow-boxes using a temperature-sensitive bifunctional additive

Zeolite Beta nanospheres and hollow-boxes are successfully obtained through a simple one-pot hydrothermal crystallization route, using tetraethylammonium hydroxide (TEAOH) as the structure-directing agent (SDA) assisted with a temperature-sensitive bifunctional additive N-methyl-2-pyrrolidone (NMP). The influences of crystallization temperature, Si/Al ratio, and TEAOH content on the synthesis and physicochemical properties of zeolite Beta as well as the formation of hollow structure are investigated in detail. It reveals that the role of NMP changes from “crystallization promoter” (CP) to “hollow-directing agent” (HDA). And the acceleration effect of NMP decreases upon the crystallization temperature (120–160 °C) due to the decomposition of TEAOH. Meanwhile, high synthesis temperature (≥180 °C), high Si/Al ratio (≥30), and low TEAOH content (TEAOH/SiO2 ≤ 0.2) may lead to the formation of undesired zeolites ZSM-5 and/or ZSM-12. The obtained Beta nanosphere and hollow-box catalysts exhibit excellent catalytic activity in the degradation of low-density polyethylene (LDPE) due to their high external surface area and acid density.

Effects of temperature and time on the facile low-temperature pre-sulfurization of tube-like unsupported Co-Mo catalysts for hydrodesulfurization

A Co-Mo sulfide catalyst with tube-like structure was prepared through a low-temperature pre-sulfurization process using rod-like CoMoO4 as the precursor. The pre-sulfurization temperature greatly affected the total pore volume, the concentration of CoMoS species, the microstructure of (Co)MoS2 slabs and the catalytic desulfurization activity. The increased temperature can promote the formation of hollow structure and the sulfurization degree of the precursor. It was found that the excessive temperature induced the Co atoms to form more isolated Co9S8 species, hindering the formation of highly active CoMoS species. Therefore, appropriate temperature is more favorable to form the (Co)MoS2 slabs with shorter length and higher stacking number, leading to more coordinatively unsaturated sites, especially the corner sites. According to the results of hydrodesulfurization reaction, the reaction rate of dibenzothiophene and the yields of liquid products are highly depended on the number of surface-active sites, which are mainly originated from the Type II CoMoS species. Moreover, the extended pre-sulfurization time can further improve the catalytic desulfurization activity of the catalyst at an appropriate pre-sulfurization temperature.

In-plane benzene incorporated g-C3N4 microtubes: Enhanced visible light harvesting and carrier transportation for photocatalytic CO2 reduction

As a promising material for photocatalytic CO2 reduction, graphitic carbon nitride (CN) and its modification has attracted significant attention. In this work, the in-plane benzene incorporated g-C3N4 microtubes were fabricated via a hydrothermal self-assembly and subsequent thermal polymerization. It is revealed that introducing the π electron-rich benzene ring into the planar structure of g-C3N4 can improve the availability of π electron and create the local asymmetry of heptazine structure. As a result, the separation and transportation of photogenerated charges are improved. Furthermore, the modified g-C3N4 possesses relatively narrow band gap and enhances light absorption. When the in-plane benzene modified g-C3N4 microtubes were applied to photocatalytic CO2 reduction with Co(bpy)3Cl2 as co-catalyst, a CO yield up to 322.66 μmol·g−1·h−1 was obtained, which was two times in comparison with the pristine g-C3N4. This work confirms the effectiveness of in-plane benzene modification and 1D hollow structure formation in improving the photoelectric performance of g-C3N4. Besides, it provides an efficient photocatalytic CO2 reduction protocol with nonmetallic semiconductor material and earth-abundant metal co-catalyst.

Formation Mechanism of Carbon-Supported Hollow PtNi Nanoparticles via One-Step Preparations for Use in the Oxygen Reduction Reaction

Hollow Pt-based nanoparticles are known to possess the properties of high electrocatalytic activity and durability. Nonetheless, their practical applications as catalytic materials are limited because of the requirement for exhaustive preparation. In this study, we prepared carbon-supported hollow PtNix (x = the moles of the Ni precursor to the Pt precursor in the catalyst preparation step) catalysts using a one-step preparation method, which substantially reduced the complexity of the conventional method for preparing hollow Pt-based catalysts. In particular, this hollow structure formation mechanism was proposed based on extensive characterizations. The prepared catalysts were examined to determine if they could be used as electrocatalysts for the oxygen reduction reaction (ORR). Among the investigated catalysts, the acid-treated hollow PtNi3/C catalyst demonstrated the best ORR activity, which was 3 times higher and 2.3 times higher than those of the commercial Pt/C and acid-treated particulate PtNi3/C catalysts, respectively.

Hollow spherical biomass derived-carbon dotted with SnS2/g-C3N4 Z-scheme heterojunction for efficient CO2 photoreduction into CO

The core of realizing the effective CO2 conversion by solar energy is to develop a stable photocatalyst with high CO2 adsorption capacity and high charge separation efficiency. In this work, a hollow spherical Z-scheme SnS2/g-C3N4/C (SCC) photocatalyst is successfully constructed by a morphology-inherited strategy. Biomass mabospores are utilized as both the precursor for formation of hollow spherical structure and carbon source, and the g-C3N4 and SnS2 nanosheets tightly anchor on the surface of mabospores-derived carbon spheres. The Z-scheme SCC heterostructure exhibits 5.5 times activity enhancement on CO2 photoreduction to CO with a high evolution rate up to 40.86 μmol∙g−1∙h−1. Examined by various photoelectrochemical analysis, the boosted photocatalytic activity originates mainly from the construction of hollow spherical Z-scheme heterojunction, providing the more preferable basic sites for CO2 adsorption, promoting the separation efficiency of electron-hole pairs, as well as increasing the reductionability of electrons in conduction band of g-C3N4. The formed internal electric fields between the g-C3N4 and SnS2 can also further reinforce the spatial separation of photogenerated charge carriers. Theoretical calculations further verify that the SCC Z-scheme heterostructure can effectively decrease the energy barriers of formed intermediates, especially the crucial COOH*, and thus leading to the facile conversion of CO2-to-CO. This work induces a new strategy to construct g-C3N4-based Z-scheme heterojunction assisted by versatile biomasses with optimized structure and enhanced photoelectrochemical merits for efficient CO2 conversion into chemical fuels.

Electrospun Cu-doped In2O3 hollow nanofibers with enhanced H2S gas sensing performance

One-dimensional nanofibers can be transformed into hollow structures with larger specific surface area, which contributes to the enhancement of gas adsorption. We firstly fabricated Cu-doped In2O3 (Cu-In2O3) hollow nanofibers by electrospinning and calcination for detecting H2S. The experimental results show that the Cu doping concentration besides the operating temperature, gas concentration, and relative humidity can greatly affect the H2S sensing performance of the In2O3-based sensors. In particular, the responses of 6%Cu-In2O3 hollow nanofibers are 350.7 and 4201.5 to 50 and 100 ppm H2S at 250 °C, which are over 20 and 140 times higher than those of pristine In2O3 hollow nanofibers, respectively. Moreover, the corresponding sensor exhibits excellent selectivity and good reproducibility towards H2S, and the response of 6%Cu-In2O3 is still 1.5 to 1 ppm H2S. Finally, the gas sensing mechanism of Cu-In2O3 hollow nanofibers is thoroughly discussed, along with the assistance of first-principles calculations. Both the formation of hollow structure and Cu doping contribute to provide more active sites, and meanwhile a little CuO can form p–n heterojunctions with In2O3 and react with H2S, resulting in significant improvement of gas sensing performance. The Cu-In2O3 hollow nanofibers can be tailored for practical application to selectively detect H2S at lower concentrations.

Dopamine- and citrate-mediated, rapid synthesis of hollow calcium carbonate nanoparticles: Their formation, metastability and transformation

Exquisite design of calcium carbonate (CaCO3) is essential to meet the demands on the properties of functional materials for various applications, where additives play a crucial role in controlling over size, orientation, polymorph, and hierarchical structure. However, we are far from achieving the elaborate control over their structures and morphologies by use of the individual additive. Herein, we develop a simple and template-free approach for the rapid fabrication of hollow CaCO3-based nanocarriers via dual-additive mediated crystallization. The roles of additives and the impact of corresponding concentrations are systematically investigated to achieve a tunable and reliable design of CaCO3 particles, simultaneously yielding clues of how the additives mediated the formation of different morphology of amorphous calcium carbonate (ACC). Compared to single citrate-mediated ACC, dual-additive mediated hollow ACC renders them the prolonged stability and also facilitates their oriented crystallization into the homogeneous hierarchical architectures. Therefore, our findings indicate that the combined additives of dopamine and citrate exert synergistic effects on hollow structure formation and metastability as well as the subsequent crystallization, which contributes to deeper insight into additive-mediated crystallization pathway. These findings may offer new opportunities to design CaCO3-based materials with controllable morphology and crystal polymorphs.

Combining Cu7S4 ultrathin nanosheets and nanotubes for efficient and selective absorption of anionic dyes

The growth of unique two-dimensional nanosheets on hollow and porous metal sulfides has received significant attention in adsorption and catalysis applications. Herein, we report a facile strategy to grow ultrathin nanosheets (NSs) on Cu7S4 nanotubes (NTs) via a two-step process (Cu7S4-NS-T). First, the obtained Cu nanowires (NWs) are oxidized in a hydrogen peroxide solution to form Cu@CuO composite nanowires decorated with ultrathin CuO NSs. Then, Cu7S4-NS-T composed of Cu7S4 NTs and Cu7S4 NSs is obtained from Cu@CuO NWs via a sulfurization process with the Kirkendall effect, in which anion-exchange reaction between Cu@CuO and S2‐− anions resulted in the formation of hollow structure. Due to fuse porous nanotubes and ultrathin nanosheets with abundant exposed copper centers, the obtained Cu7S4-NS-T shows extraordinary adsorption ability for the removal of anionic dyes, such as Congo red (CR) with a maximum adsorption capacity of 1166.07 mg/g, much superior to that of commercial activated carbon. Adsorption equilibrium and kinetic studies indicate that chemisorption is the main control process for the enrichment of the anionic dyes. The Cu7S4-NS-T can be used as a novel effective adsorbent for rapidly and efficiently removing dyes contaminants in water.

Hollow nitrogen-doped carbon nanospheres as cathode catalysts to enhance oxygen reduction reaction in microbial fuel cells treating wastewater

Hollow nanospheres play a pivotal role in the electro-catalytic oxygen reduction reaction (ORR), which is a crucial step in microbial fuel cell (MFC) device. Herein, the hollow nitrogen-doped carbon nanospheres (HNCNS) were synthesized with the sacrifice of silica coated carbon nanospheres (CNS@SiO2) as template. HNCNS remarkably enhanced the ORR activity compared to the solid carbon and solid silica spheres. By tuning calcination temperature (800–1100 °C), the surface chemistry properties of HNCNS were effectively regulated. The optimal HNCNS-1000 catalyst which was calcined at 1000 °C exhibited the highest ORR activity in neutral media with the onset potential of 0.255 V and half-wave potential of −0.006 V (vs. Ag/AgCl). Single chamber MFC (SCMFC) assembled with HNCNS-1000 cathode unveiled comparable activity to a conventional Pt/C reference. It showed the highest maximum power density of 1307 ± 26 mW/m2, excellent output stability of 5.8% decline within 680 h, chemical oxygen demand (COD) removal of 94.0 ± 0.3% and coulombic efficiency (CE) of 7.9 ± 0.9%. These excellent results were attributed to a cooperative effect of the optimized surface properties (e.g., structural defects, relative content of pyrrolic nitrogen and specific surface area) and the formation of hollow nanosphere structure. Furthermore, the positive linear relationship of the structural defects and pyrrolic nitrogen species with the maximum power generation in SCMFC were clearly elucidated. This study demonstrated that the cost effective HNCNS-1000 was a promising alternative to commercial Pt/C catalyst for practical application in MFCs treating wastewater. Our result revealed the effectiveness of MFC fabricated with HNCNS-1000 cathode catalyst in terms of power generation and wastewater treatment.

Preparation of a hollow HZSM-5 zeolite supported molybdenum catalyst by desilication-recrystallization for enhanced catalytic properties in propane aromatization

A hollow HZSM-5 supported molybdenum (Mo) catalyst was successfully prepared by desilication-recrystallization method of HZSM-5 in tetrapropylammonium hydroxide (TPAOH) solution. The as-synthesized catalyst exhibiting excellent performance in propane aromatization reaction was thoroughly investigated, along with the mechanism for the formation of hollow structure and mechanism for the deactivation. Results revealed that TPA ​+ ​exerted a controllable desilication and recrystallization effect. Compared with Na2CO3 treatment which led to a mesoporous structure, TPAOH treatment was able to leach out the inner Si species by OH- and then those Si species recrystallized on the external surface, resulting in the hollow structure and a silicon-rich external surface. In addition, the hollow zeolite exposing higher external surface provided more anchoring sites for Mo species, which was beneficial to the Mo related Lewis acid sites but decreased the surface Bronsted acidity. At 823 ​K and a space velocity of 1800 ​mL·g-1·h-1, the hollow Mo/HZSM-5(TPAOH) catalyst behaved a propane conversion of 73.01% and aromatics selectivity of 77.36%, exceeding those of the hierarchical Mo/HZSM-5(Na2CO3) catalyst by 5.97% and 9.96%, respectively. These features of Mo/HZSM-5(TPAOH) granted it superb diffusion ability and optimized Bronsted/Lewis acid ratio (B/L ​= ​1.3), which greatly enhanced the propane conversion and aromatic selectivity together with a preeminent catalytic stability.

Stable zero-dimensional cesium indium bromide hollow nanocrystals emitting blue light from self-trapped excitons

The growing demand for lighting and displays has motivated intensive research in metal-halide perovskite nanocrystals (NCs) recently. However, the development of blue-emissive perovskite NCs lag behind those of green and red ones severely; moreover, the conventional lead-halide perovskites contain toxic element lead. In this study, zero-dimensional Cs3InBr6 NCs with intrinsic broadband blue emission (~ 450 nm) were developed for the first time. Joint experiment-theory characterizations reveal the excited-state structural distortion of [InBr6]3− cluster enables the formation of self-trapped excitons, which contribute the broadband emission. Apart from the solid structure, hollow NCs with controlled particle and pore sizes were obtained resulting from the Ostwald ripening mechanisms. Theoretical calculations show that the easy diffusion of Br vacancies in Cs3InBr6 lattices assist the formation of hollow structure. Encouraged by the remarkable structural and optical stability of hollow Cs3InBr6 NCs, such lead-free NCs may open up new avenues for manufacture of optoelectronic devices.