Flower-like Architectures Research Articles

Hydrogen generation from catalytic hydrolysis of sodium borohydride by a Cu and Mo promoted Co catalyst

Catalytic hydrolysis of chemical hydrides with the use of NaBH4 is a safe and effective way to provide hydrogen fuel for new energy vehicles and portable electronic devices. Herein we developed a Cu and Mo promoted Co hierarchical composites (Co1−xCuxMoO4) for hydrolysis of NaBH4 via an easy synthesis route. FESEM analysis depicts that the morphology of Co1−xCuxMoO4 hierarchical composites varied significantly from irregular microsphere to marigold microsphere to rose like morphology with the increase in Cu (x) ratio with respect to Co (1 − x). Flower-like morphological architecture and crystal configuration empower the supported catalyst to exhibit a remarkable catalytic activity and outstanding catalytic activity was obtained for marigold-like Co0.9Cu0.1MoO4 catalyst with an H2 generation rate of 1005.7 mL min−1 g−1, which confirms existence of synergistic effect between Co, Cu and Mo. Lower loading of Cu in Co1−xCuxMoO4 supported the active sites of Co to increase its catalytic activity. Additionally, the catalyst exhibits good recyclability after five successive runs of hydrolytic reaction, making it a robust catalyst for hydrolysis of NaBH4 and could be considered as a potential catalyst for portable hydrogen fuel systems.

A High-Capacity Ammonium Vanadate Cathode for Zinc-Ion Battery

Highlights3D flower-like architecture assembled by NH4V4O10 nanobelts (3D-NVO) was fabricated.The Zn2+ ion was intercalated into NVO cathode within the interlayer region (NH4V4O10 ↔ ZnxNH4V4O10).The 3D-NVO cathode could deliver a large reversible capacity of 485 mAh g−1 at a current density of 100 mA g−1 for zinc-ion battery.

Flexible Active-Site Engineering of Monometallic Co-Layered Double Hydroxides for Achieving High-Performance Bifunctional Electrocatalyst toward Oxygen Evolution and H2O2 Reduction.

It is highly desirable but challenging to develop a facile and scalable strategy to synthesize efficient bifunctional electrocatalysts for oxygen evolution and H2O2 reduction by engineering the active site of monometallic-layered double hydroxides (LDHs). Herein, we developed a convenient, efficient, and scalable method for the construction of monometallic Co-LDHs with tunable Con+ (n = 2, 3) concentration by a one-pot solvothermal reaction in a short time (e.g., 2 and 4 h) using only cobalt nitrate and hexamine as raw materials. The catalytic performance of Co-LDHs was mainly determined by the Con+ (n = 2, 3) concentration, which could be simply regulated by tuning the solvothermal time. Combining the joint merits of three-dimensional flowerlike architecture (abundant accessible active sites and a fast electron/mass transport), Co-LDHs-4 with abundant Co3+ species exhibited an excellent electrocatalytic activity for oxygen evolution reaction in terms of a low overpotential at 10 mA cm-2 (η10 = 241 mV) and long-term durability for 70 h at 100 mA cm-2, better than the state-of-the-art IrO2 and most of the reported analogues. Besides, Co-LDHs-2 enriched in Co2+ displayed a superior electrochemical activity for H2O2 detection with a broad linear range (0.002-20 mM), a low detection limit (0.002 mM), and a high response sensitivity (272.02 μA mM-1 cm-2). Therefore, this work opens a new horizon for the rational development of a highly active electrocatalyst with tunable concentrations of active components.

Complex SiOC ceramics from 2D structures by 3D printing and origami

Manufacturing of ceramic components with a geometrically complex 3D architecture and highly detailed features for use in a variety of practical applications is still a challenge. In our investigation, we adopted a synergistic strategy for fabricating SiOC ceramics with intricate 3D morphologies by additive manufacturing and origami technique or assemblage, taking advantage of the high printability and flexibility of a commercially available silicone elastomer. Secondary shaping using origami of different 2D layers with varied design allowed the manufacturing of spiral, flower-like and polyhedron architectures, which are difficult to fabricate without adding supports or by any conventional ceramic fabrication processes. Produced samples showed no cracks or pores and fully retained the given shape after pyrolysis.

Near-infrared reflectance and thermal insulating performance of Mo-doped Bi2WO6 with 3D hierarchical flower-like structure as novel ceramics pigment

The pigments with the formula of Bi2W1−xMoxO6 (x = 0.0, 0.1, 0.2, 0.3, 0.4) are synthesized by one step hydrothermal method. The pigments are characterized with XRD, FE-SEM, XPS, UV/VIS/NIR spectrometer, thermal conductivity and TG-DTA. The results reveal that the samples are of orthorhombic phase with no impurity phase existing and three-dimensional hierarchical flower-like architectures with diameter ranging from 2 to 3 μm. The color of the doped samples progressively transfers from pale yellow to yellow. The band gap decreases from 2.82 eV to 2.42 eV, which is attributed to the charge transfer excitation changes from Bi 6s → O 2p to the transition of Mo 3d → O 2p. As compared with the conventional pigments with similar color, the Mo-doped Bi2WO6 pigments perform better on the near-infrared solar reflectivity and the highest near-infrared solar reflectance is as high as 80.80%. The distinction of the NIR solar reflectance values among the pigments is majorly attributed to the different oxygen concentration induced by the reaction formula: Bi2Mo1-xWxO6 → Bi2Mo1-xW6+x-δ(W6+·2e) δO6-δ + δ2O2↑.The thermal conductivity of some Mo-doped Bi2WO6 pigments is apparently lower than its pigment counterpart owning to the 3D hierarchical flower-like structure. The pigments are also possessing eminent thermal and chemical stability. The Mo- doped Bi2WO6 samples not only have high near-infrared reflectance with beautiful color but also have comparatively benign thermal insulating performance, so that they are promising to be served as novel amiable ceramic pigments to manipulate the thermal property of ceramic materials.

A High-Temperature Na-Ion Battery: Boosting the Rate Capability and Cycle Life by Structure Engineering.

High-temperature sodium ion batteries (SIBs) have drawn significant heed recently for large-scale energy storage. Yet, conventional SIBs are in the depths of inferior charge/discharge efficiency and cyclability at elevated temperatures. Rational structure design is highly desirable. Hence, a 3D hierarchical flower architecture self-assembled by carbon-coated Na3 V2 (PO4 )3 (NVP) nanosheets (NVP@C-NS-FL) is fabricated via a microwave-assisted glycerol-mediated hydrothermal reaction combined with a post heat-treatment. The growth mechanism of NVP@C-NS-FL is systematically investigated, by forming a microspherical glycerol/polyglycerol-NVP complex initially and then converting into flower-like architecture during the subsequent annealing at a low temperature ramping rate. Benefiting from the integrated structure, fast Na+ transportation, and highly effective heat transfer, the as-obtained NVP@C-NS-FL exhibits an excellent high-temperature SIB performance, e.g., 65 mAh g-1 (100 C) after 1000 cycles under 60 °C. When coupled with NaTi2 (PO4 )3 anode, the full cell can still display superior power capability of 1.4 kW kg-1 and long-term cyclability (2000 cycles) under 60 °C.

Superior potassium-ion storage properties by engineering pseudocapacitive sulfur/nitrogen-containing species within three-dimensional flower-like hard carbon architectures

Rechargeable non-aqueous potassium-ion batteries have been regarded as one of ideal candidates for large-scale electric energy storage applications. However, the achievement of high reversible capacity and rate capability is still a great challenge. In this work, an extraordinary S-/N-/O- multielement-doped three-dimensional (3D) flower-like hard carbon architecture is firstly proposed as promising anode material for low-cost potassium-ion batteries. The 3D flower-like architecture not only provides abundant exposed surface-active sites but acts as highly conductive interconnected network for electron transport. More encouragingly, the introduction of highly reactive -N-Cx-S- species has been revealed to show highly reversible pseudo-capacitive charge storage behavior, inherently enlarging the slope reversible capacity to the highest value of 423 mAh g−1 at low current density of 0.05 A g−1. As well, benefitted from the structural and compositional advantages, an unprecedented rate capability (251 mAh g−1 at 1.0 A g−1) and stable cycling stability (362 mAh g−1 after 300 cycles at 0.5 A g−1) has been obtained, which outperforms most of carbonaceous materials for K-ion storage. Our present work not only provide new understandings on surface/conversion-synergistic driven K-ion storage mechanisms but offer effective material engineering strategies for improving the properties of potassium-ion batteries.

Hydrothermal Synthesis of Hierarchical Flower-Like Sn3O4 Nanomaterial for High-Photocatalytic Properties

Nanostructured tin oxide has drawn extensive attention from researchers as a semiconductor, owing to its unique physicochemical properties. In this study, a mixed-valence tin oxide, hierarchical flower-like Sn3O4 self-assembled with numerous nanosheets was successfully synthesized using a simple hydrothermal process. The structure, morphology, and specific surface area were characterized using X-ray diffraction (XRD), a scanning electron microscope (SEM), and an automatic surface area analyzer, respectively. The obtained Sn3O4 products had hierarchical nanostructures and uniform flower-like morphology. The diameter of this flower ranged from 300 nm to 2.6 μm. The flower-like Sn3O4 was self-assembled by nanosheets with a thickness of 8 ∼25 nm. By controlling the temperature of hydrothermal reaction and the concentration of surfactant, the as-synthesized hierarchical flower-like Sn3O4 (Sn3O4−25SC) can obtain the largest specific surface area of approximately 66 m2∙g−1, and thus exhibits excellent photocatalytic activity while degrading the methylene blue (MB) aqueous solution under UV light irradiation. Results show that the degradation rate of dye MB can reach 97% within 60 min. Moreover, a possible growth mechanism of the flower-like architectures was proposed. Sodium citrate promotes the growth of Sn3O4 nanosheets and accelerates the self-assembling of nanosheets into flower-like architecture.

Houttuynia-derived nitrogen-doped hierarchically porous carbon for high-performance supercapacitor

Three-dimensional (3D) heteroatom-doped nanostructured carbon materials have gained extensive attention because of their tremendous potential for enhancing supercapacitor performance. Herein, based on a mild carbonization/activation process we successfully developed green/sustainable 3D hierarchically porous nitrogen-doped nanostructure carbon (N–HNC) materials from houttuynia biomass, showing high specific capacitance and high cyclic stability. The as-prepared houttuynia-derived porous carbon material shows a unique flower-like architecture with well-distributed micro/meso pores and a high specific surface area of 2090 m2/g. The assembled supercapacitor based on N–HNC sample shows superior specific capacitance (473.5 F/g at 1 A/g) and remains over 50% of specific capacitance at 20 A/g. The N–HNC based symmetric supercapacitor, constructed with a two-electrode configuration, shows an energy density of 15.99 Wh/kg at 500 W/kg and outstanding capacitance retention of 95.74% even after 10,000 charge-discharge cycles at 10 A/g in an aqueous 6 M KOH electrolyte system. The results highlight the potential of the 3D porous N-doped hierarchical nano-structural carbon materials from houttuynia biomass as candidate electrodes for supercapacitor applications. This study provides an example of using the inherent framework structure of biomass as a precursor to synthesize hierarchically porous nitrogen-doped nanostructure for high-performance supercapacitor applications.

Correction: A facile template-free synthesis of Bi2Sn2O7 with flower-like hierarchical architecture for enhanced visible-light photocatalytic activity

Correction for ‘A facile template-free synthesis of Bi2Sn2O7 with flower-like hierarchical architecture for enhanced visible-light photocatalytic activity’ by Chenyan Wu et al., New J. Chem., 2020, 44, 11196–11202, DOI: 10.1039/D0NJ01690J.

Controllable synthesis, characterization and photoluminescence properties of flower-like BaMoO4 hierarchical architectures

Flower-like BaMoO4 hierarchical architectures were prepared by a facile solvothermal method. A nucleation–oriented attachment–assembly–Ostwald ripening mechanism is presented for the formation of the BaMoO4 samples.

A flower-like CoS2/MoS2 heteronanosheet array as an active and stable electrocatalyst toward the hydrogen evolution reaction in alkaline media

CoS2/MoS2 heteronanosheet arrays (HNSAs) with vertically aligned flower-like architectures are fabricated through in situ topotactic sulfurization of CoMoO4 nanosheet array (NSA) precursors on conductive Ni foam. CoMoO4 NSAs are prepared by a self-template hydrothermal method without using any hard template and surfactant. Benefiting from a 3D flower-like architecture constituted by ultrathin nanosheets with abundant exposed heterointerfaces as highly active sites and predesigned void spaces, the as-synthesized CoS2/MoS2 HNSAs exhibit an excellent hydrogen evolution reaction (HER) performance with a low overpotential of 50 mV at 10 mA cm−2, and a small Tafel slope of 76 mV dec−1 in 1.0 M KOH, which outperforms most previously reported CoS2 and MoS2 based electrocatalysts with compositional or morphological similarity. This work demonstrates the great potential in developing high-efficiency and earth-abundant electrocatalysts for alkaline HER through heterointerface engineering and morphological design by utilizing transition metal molybdate as a promising platform.

Highly efficient adsorption and recycle of phosphate from wastewater using flower-like layered double oxides and their potential as synergistic flame retardants

Here, a novel Mg/Al-layered double oxide (MgAl-LDO) with a flower-like architecture was synthesized through facile green co-precipitation and calcination methods for phosphate separation and recycle from wastewater. The as-prepared MgAl-LDO demonstrated high specific surface area of 200.17 m2/g based on its 3D hierarchical flower-like structure. The phosphate adsorption was well conformed to Pseudo-second-order kinetic model and Langmuir model, suggesting a homogeneous monolayer chemisorption with a maximum adsorption capability of 103.61 mg P/g. The existence of Cl−, NO3− ions did not interfere with phosphate adsorption, while high concentration SO42− and CO32− affected the phosphate adsorption. In addition, adsorption mechanism analysis revealed that high-efficiency phosphate capture by MgAl-LDO was mainly due to the electrostatic adsorption, surface inner-sphere complexation, ligand exchange and precipitation combined process. Remarkably, the phosphate adsorbed MgAl-LDO (P-LDO) can be employed as synergistic flame retardant to improve the flame retardancy of paper.

A simplistic approach for the synthesis of CuS-CdS heterostructure: A novel photo catalyst for oxidative dye degradation

Direct synthesis of CuS-CdS based mesoporous composite materials and their photocatalytic activity are delineated. In this study, a series of CuS micro flowers (mf) decorated with varying amounts of CdS nanoparticles (NP) have been synthesized successfully in a controlled manner. Relatively easy synthesis of material along with its surfactant-free clean surfaced heterojunction accentuates the reliability of the protocol described here. Full characterization of these semiconducting materials was accomplished with a series of analytical techniques, which include powder x-ray diffraction (PXRD), scanning electron microscopy (SEM), tunnelling electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), UV–vis, IR, BET and lifetime studies. Upon varying the concentration of precursor of Cd in the reactions, the resulting materials exhibited a well-demarcated change in morphologies ranging from undifferentiated mass to well-differentiated flower-like architectures. The thoroughly characterized composite was accessed finally for its potential photocatalytic activity for the degradation of organic dyes. The results showed 96.0% degradation of rhodamine B (RhB) over 10 min and 94.7% degradation of methylene blue (MB) over 9 min. This observed rate of degradation was much higher compared to that observed in the case of pure CuS (62.0% of RhB and 50.2% of MB).

MnO2/SWCNT buckypaper for high performance supercapacitors

Abstract We report the supercapacitive performance of manganese oxide (MnO2)/single-walled carbon nanotube (SWCNT) buckypaper electrodes enabled via electrochemical deposition of MnO2 onto SWCNT buckypaper for the first time. The entangled SWCNT network provides electro-conductive pathways for the charge transfer. We demonstrate that the MnO2/SWCNT buckypaper supercapacitor exhibits a specific capacitance of 605 Fg−1 and gravimetric energy density of ∼120 Whkg−1. Furthermore, our MnO2/SWCNT buckypaper electrode shows excellent rate capability (85% capacity retention at 20 Ag−1) and long cycle life (1% capacity loss after 10,000 charge/discharge cycles). The excellent performance of MnO2/SWCNT buckypaper supercapacitor is attributed to the flower-like unique hierarchical porous architecture of MnO2 around SWCNTs arranged in “pearl necklace” formation, enabling large electrode/electrolyte interface and charge storage surface, better electrolyte penetration, and rapid charge transfer. The results suggest that the MnO2/SWCNT buckypaper electrode can provide excellent supercapacitive performance suitable for future generation electric vehicles.

Biomass carbon modified flower-like Bi2WO6 hierarchical architecture with improved photocatalytic performance

Novel Biomass carbon modified Bi2WO6 with 3D flower-like nanostructures were firstly fabricated through a hybridization approach, and investigated by multiple techniques including XRD, XPS, SEM and TEM analysis, etc. Compared with the pristine Bi2WO6, Bi2WO6/C hybrids exhibit higher visible-light photocatalytic activity and stability for tetracycline (TC) photodegradation. Moreover, the obviously enhanced photodegradation performance of Bi2WO6/C hybrids was mainly attributed to the modification of biomass carbon with good natures in specific surface area, narrow band gap (2.51 eV) and electronic transmission, which greatly improved the adsorption capacity and facilitated the separation of charge carriers. Furthermore, a possible photocatalytic mechanism of Bi2WO6/C hybrids in the view of active radicals has been discussed, which was also ascribed to the outstanding degraded ability of the ·OH evolved from the supersaturated ·O2− through trapping and ESR experiments. More importantly, these findings provide new insights to the utilization of biomass carbon modified other Bi-based photocatalysts and enhancing the photocatalytic performance to address environmental problems.

Three-Dimensional Hierarchical Flowerlike FeP Wrapped with N-Doped Carbon Possessing Improved Li+ Diffusion Kinetics and Cyclability for Lithium-Ion Batteries.

Transition-metal phosphides have a potential application in lithium-ion batteries (LIBs) because of their high theoretical capacities and low cost; nevertheless, they possess dramatic volumetric variation during cycling associated with poor conductivity, limiting their practical applications. Here, a three-dimensional (3D) hierarchical flowerlike FeP coated with nitrogen-doped carbon layer (FeP@N,C hybrid) was constructed through a solvothermal method, followed by a phosphating approach under low temperature. N-doped carbon not only suppresses the volume fluctuation of FeP, but also promotes electron transfer, accompanied by catalyzing the decomposition of Li3P to improve the reversibility of the FeP@N,C hybrid during cycling processes. In addition, a 3D flowerlike architecture assembled from porous nanosheets is also beneficial for shortening the migration path of ions as well as improving the contact area of electrode with electrolyte, which enhances the reaction kinetics and is proved by both experimental measurement of Li+ diffusion coefficient and resistivity, along with the calculation of density functional theory. Consequently, the 3D hierarchical flowerlike FeP@N,C hybrid performs excellent cyclic stability (569 mA h g-1 at a current density of 500 mA g-1 for the 300th cycle) and rate performance (331.94 mA h g-1 at a high current density of 5 A g-1) for LIBs. Based on above results, the fabrication strategy in this work could offer a thought to design other high-performance metal phosphide hybrids.

Self-Assembled 3D Flower-like Composites of Heterobimetallic Phosphides and Carbon for Temperature-Tailored Electromagnetic Wave Absorption.

Bimetallic cobalt-nickel phosphides as a microwave absorber with a well-defined 3D hierarchical flower-like architecture featuring the ultrathin 2D subunits are very unusual and rarely reported. Herein, for the first time, we successfully prepared 3D flower-like CoNi-P/C composites with 2D nanosheet subunits via a one-pot solvothermal self-assembled strategy followed by a one-step carbonization-phosphorization process. Interestingly, the chemical composition and electromagnetic (EM) wave absorption performance of composites are highly influenced by the calcination temperature. As the calcination temperature increases from 300 to 500 °C, the crystal pattern transformed from CoP with nickel ions uniformly intercalating into the lattice to the CoNiP structure. Comparing with CoNi-P/C-400 and CoNi-P/C-500, the CoNi-P/C-300 sample exhibited an optimal reflection loss (RL) value of -65.5 dB at 12.56 GHz with a thickness of 2.1 mm and an ultralow filler loading of 15 wt %. Furthermore, the fundamental EM wave absorption mechanism was proposed. The synergetic effects of dramatical attenuation ability and well-matched impedance endue CoNi-P/C-300 with superior microwave absorption performance. This work may be enlightening in promoting the development of heterobimetallic phosphides in the wave-absorbing field due to their intrinsic magnetism, higher electrical conductivity, as well as eco-friendly traits.

Palladium nanoparticles uniformly and firmly supported on hierarchical flower-like TiO2 nanospheres as a highly active and reusable catalyst for detoxification of Cr(VI)-contaminated water

The rational design of highly active and stable nanocatalysts towards the detoxification of Cr(VI)-contaminated water is of great importance for environmental remediation. In the present work, a novel Pd-based hybrid nanomaterial, composed of Pd nanoparticles (Pd NPs) supported on three-dimensional hierarchical titania nanoflowers (fTiO2), was fabricated and systematically investigated as the catalyst of chromium detoxification. Pd NPs with diameter of ~ 2.8 nm were found to be uniformly and firmly supported onto the crystalline nanosheets of fTiO2. More importantly, the highly open porous flower-like architecture of Pd NPs/fTiO2 could not only endow the catalyst with high surface area (237.5 m2 g−1) and large pore volume (0.86 cm3 g−1), but also facilitate reactant diffusion and exposure of active sites. Benefitting from these remarkable features, the Pd NPs/fTiO2 exhibited superior catalytic performance for reduction of Cr(VI) in the presence of formic acid. The TOF reached up to 633.0 h−1, which was several and even more than one hundred times as high as those obtained by previously reported supported Pd-based catalysts. Moreover, the catalytic activity of Pd NPs/fTiO2 could remain almost unchanged after being recycled several times, demonstrating its long-term stability. Therefore, the Pd NPs/fTiO2 would be promising for practical wastewater treatment.

A dual mode photoelectrochemical sensor for nitrobenzene and L-cysteine based on 3D flower-like Cu2SnS3@SnS2 double interfacial heterojunction photoelectrode

In this work, 3D hierarchical Cu2SnS3@SnS2 flower assembled from nanopetals with sandwich-like Cu2SnS3-SnS2-Cu2SnS3 double interfacial heterojunction was successfully designed and synthesized on fluoride doped tin oxide (FTO) for photoelectrochemical (PEC) sensor by in situ electrodeposition p-type Cu2SnS3 nanoparticles on both inner and outer surfaces of n-type SnS2 nanopetals. The unique double interfacial heterojunction simultaneously combines 3D flower-like architectures to drastically increase the light trapping and absorption in visible-near infrared range (Vis-NIR), and dramatically inhibites the charge carrier recombination, which is crucial for boosting the PEC activity. Benefitting from the shape and compositional merits, the Cu2SnS3@SnS2 heterojunction possess dual-mode signal by controlling the electrodeposition time to manipulate the composition ratio of Cu2SnS3 and SnS2. The Cu2SnS3@SnS2/FTO electrode not only exhibits excellent photoeletro-reduction capacity for ultra-sensitive sensing trace persistent organic pollutant (nitrobenzene, NB), but also presents photoeletro-oxidization activity for high selective detection of L-cysteine (L-Cys) without any auxiliary enzyme under the light illumination. Dual mode sensor displayed superb performance for the detection of NB/L-Cys, showing a wide linear range from 100 pM to 300 μM/10 nM to 100 μM and a low detection limit (3S/N) of 68 pM/8.5 nM, respectively. Such a tunable double interfacial heterojunction design opened up new avenue for constructing multifunction PEC sensing platform.