Hierarchical Nanoflowers Research Articles

Chemiresistive room temperature H2S sensor based on CunO nanoflowers fabricated by laser ablation

Hierarchical CunO nanoflowers were synthesized through the laser ablation of a CuO target in NaOH solutions for room-temperature (27 ℃) H2S detection. Notably, the pH value of NaOH solutions influenced both the micro-morphologies and compositions of the CunO products, as evidenced by XRD, XPS, SEM and TEM. In high pH solutions, the specific surface area of the CunO products increased, their thickness decreased, and the Cu2O content diminished, resulting in enhanced sensitivity, selectivity and stability of the CunO products’ response to H2S. Notably, the pH14# sample synthesized using an NaOH solution with a pH value of 14 featured pure CuO nanoflowers comprising slightly curled nanosheets with a thickness of approximately 10 nm. This sensor demonstrated excellent H2S sensing performance at room temperature, exhibiting a response value of 1.17 for 10 ppb H2S, along with high selectivity and good long-term stability. However, after exposure to H2S, the resistance of the sensor did not recover to its baseline in air at room temperature. Thermogravimetry results revealed that a temperature of 300 °C was effective for recovery of the sensor. Consequently, the operation temperature of the pH14# sensor was controlled using a micro-hotplate. In the pulse heating mode, the sensor’s response to 100 ppb H2S was 1.5, with a response time of 135 s and a recovery time of 137 s.

Efficient hydrodeoxygenation of cresol by hierarchical porous FLRC-TiO2 nanoflower

The construction of highly efficient and selective hydrodeoxygenation (HDO) catalysts is of great significance for upgrading pyrolysis oil. In this work, nickel and iron-based NiFe(x)/FLRC-TiO2 catalysts with a flower-like radial channel structure were successfully fabricated with a facile strategy. The effects of Ni/Fe molar ratios and operation conditions on the structure, morphology and HDO performance were investigated using p-cresol as model compound. Impressively, the NiFe(x)/FLRC-TiO2 catalysts exhibit a well-defined radial channel structure with an average pore diameter of 27.4 nm and the NiFe(5)/FLRC-TiO2 with appropriate Ni/Fe ratio of 5 exhibits the best HDO performance. Under the conditions of T=275 °C, p=3 MPa, and t=2.5, the conversion rate of p-cresol and the selectivity to the target product MCH reaches 100 % and 97.8 %, respectively, which supresses most of the reported Ni based catalysts. Combining with the structure and morphology charateriazation results, this excellent HDO performance could be ascribed to: (a) the unique flower-like radial channel structure of the catalysts stemmed from FLRC-TiO2 provides more exposed active sites for HDO and fast mass transfer; (b) an appropriate Ni/Fe ratio contributes to the increase of specific surface area and pore volume of the catalyst, which boots the higher catalytic HDO activity; (c) the addition of Fe enhances acidity of catalyst and promotes the hydrodehydration of C–OH to target product MCH, together with the synergistic effect of FeNi metal sites, favoring the higher catalytic HDO activity. The proposed strategy for the preparation of radial channel structure FLRC-TiO2 support can be extended to various other reactions.

Sunlight-promoted CO2 electroreduction with staggered p-n heterojunction by indium-doped bismuth 3D nanoflower structure on oxidized copper foam as self-standing photoelectric cathode over a wide potential window

Exploiting suitable photocathodes to achieve high photocurrent and long-term endurance is still a great challenge in photoelectrocatalytic CO2 reduction (PEC CO2) reactions. Herein, an In-doped Bi2O3 decorated oxidized copper foam (CBIO/CF) self-standing photoelectric cathode is well designed by the self-assembly process without an externally added binder. Via sunlight-promoted strategy, CBIO/CF with a unique 3D hierarchical nanoflower structure displays a superior faradaic efficiency of 90.0 % towards HCOOH over a wide potential window from −0.87 ∼ −1.17 VRHE and reaches 97.8 % at −0.87 VRHE with a partial current density of 14.41 mA cm−2. The in-situ Fourier transform infrared spectroscopy (FTIR) analysis demonstrates the abundant oxygen defects induced by In doping boost CBIO/CF absorbing substantive intermediate species related with formate generations, and porous structure accelerating mass transportation. Moreover, the well-designed staggered p-n heterojunctions of Cu2O and In-doped Bi2O3 on the surface of catalysts favor the generation and separation of electron/hole pairs and contribute to the photocatalytic reduction of CO2 under a bias voltage. This work paves the way for rational regulation of self-supporting photoelectrode for PEC CO2 to HCOOH with suitable conduction band valence bands and high performance and stability.

Oxygen electrocatalysis-driven electrochemiluminescence by hierarchical carbon nanoflower-supported copper-modulated cobalt sulfide for cytosensing.

A facile cation modulation strategy is proposed for the synthesis of copper/cobalt bimetallic sulfides dispersed on hierarchical carbon nanoflowers, which exhibit excellent oxygen electrocatalysis capacity to drive electrochemiluminescence for cytosensing.

Novel three-dimensional architectured ZnMgAl ternary layered double hydroxide@reduced graphene oxide nanocomposites as electrode material for high-performance supercapacitor

Ternary layered double hydroxides (LDH) have recently attracted immense attention owing to their stupendous features, such as fine compositional tuning, multiple valence states, and superior electrochemical activity. Moreover, their intriguing structures and distinctive physiochemical properties delineate them as an exemplary material to serve as electrodes for high-performance supercapacitors (SCs). The present work reports the in-situ synthesis of Zinc Magnesium Aluminium LDH (ZMA) integrated with reduced graphene oxide (rGO) through a single-step hydrothermal approach. The resulting novel ternary ZMA@rGO nanocomposite (ZMAG) possesses a unique architecture incorporating hierarchical 3D nanoflowers of ZMA embedded on graphene nanosheets. The porous morphology of LDH improves interfacial charge transport, which results in more faradaic reactions at the electrochemically active sites. In addition, the conductive graphene nanosheets render a high specific surface area, endowing excellent capacitive behavior. The amalgamated electrochemical properties of ZMA and rGO develop a competent electrode material (ZMAG) for SCs. The ZMAG2 nanocomposite having ZMA and rGO in 1:1, evinces a specific capacitance (Cs) of 656.7 F/g at a current density (Id) of 1 A/g. Furthermore, the asymmetric supercapacitor (ASC) features admirable cycle stability (retains 89% of initial capacitance after 15,000 charge/discharge cycles). Herein, the real-time application of ZMA@rGO//AC ASC has also been demonstrated. Therefore, hierarchical porous nanostructure proclaims new prospects for fabricating proficient electrode materials for energy storage devices.

Hierarchical Au Nanoflowers Formed in an Ionic Liquid/Water System for Bacterial Inhibition

Hierarchical Au Nanoflowers Formed in an Ionic Liquid/Water System for Bacterial Inhibition

Hierarchical Magnetic Carbon Nanoflowers for Ultra-Efficient Electromagnetic Wave Absorption.

Porous carbon nanomaterials are widely applied in the electromagnetic wave absorption (EMWA) field. Among them, an emerging flower-like carbon nanomaterial, termed carbon nanoflowers (CNFs), has attracted tremendous research attention due to their unique hierarchical flower-like structure. However, the design of flower-like carbon nanomaterials with different magnetic cores for EMWA has rarely been reported. Herein, a general template method is proposed to achieve a set of high-quality magnetic CNFs, namely Co@Void@CNFs, CoNi@CNFs, and Ni@CNFs. The prepared magnetic CNFs have highly accessible surface area and internal space, rich heteroatom content, multi-scale pore system, and uniform and highly dispersed magnetic nanoparticles, as a result, deliver superior EMWA performance. Specifically, when the thickness is 2.6mm, the Co@Void@CNFs exhibit a maximum refection loss (RLmax) of -56.6dB and an effective absorption bandwidth (EAB) from 8.0 to 12.1GHz covering the whole X band. The CoNi@CNFs have an RLmax of up to -57.6dB and a wide EAB of 5.6GHz at just 1.9mm. For the Ni@CNFs, possess an ultra-broad EAB of 6.1GHz, covering the entire Ku band at 2.0mm. Overall, the hierarchical magnetic carbon nanoflowers proposed here offer new insights toward realizing multifunctional integrated carbon nanomaterials for EMWA.

Covalently Linked Pigment@TiO2 Hybrid Materials by One‐Pot Solvothermal Synthesis

Hybrid materials (HMs) combine the high diversity of functionalities of organic compounds with properties typical for inorganic materials, such as high mechanical strength or high thermal stability. Herein, HMs combining organic pigment molecules and TiO2 as inorganic component, with covalently linked components, i.e., so‐called class II HMs, are reported. The synthesis of such HMs is intrinsically challenging, as the apolar organic pigment component and the inorganic polar TiO2 component require different conditions for their respective formation. Herein, we circumvent this issue by employing solvothermal synthesis in superheated isopropanol, which through temperature tunability of the solvent properties allows for both generating and linking both components in one‐pot. First, it is shown that an organic benzimidazole‐based pigment molecule designed for readily binding to Ti can be synthesized solvothermally. Second, new class II titanium‐based HMs are generated from Ti(OiPr)4 and pigment precursors in a solvothermal reaction. The pigment@TiO2 HMs feature significant porosity and are structurally identified as layered structures of lepidocrocite‐like TiO2 linked via pigment molecules. These layered HMs assemble into hierarchical nanoflowers, and depending on the pigment segments, different interlayer spacings in between inorganic layers are observed. Third, the pigment@TiO2 materials are shown to be usable as electrode materials in lithium‐ion batteries.

An efficient multifunctional SnS2/g-C3N4 hierarchical nanoflower catalyst for electrocatalytic and photocatalytic applications

The rising energy demand via renewable sources and existence of organic pollutants in water has attracted the world-wide attention to attain sustainable ecosystems. The development of a multi-functional catalyst with significant economic and environmental implications remains a challenge. Herein, we synthesized SnS2/g-C3N4 hierarchical nanoflower using solvothermal method, verified by XRD and FTIR investigations. The surface morphology was analyzed using FESEM, TEM and HRTEM while optical absorption via UV–Vis spectroscopy. SnS2/g-C3N4 displayed outstanding electrocatalytic activity for HER and OER with smaller tafel slope and higher values of current density. The results are in accordance with Cdl and ECSA values, ensuing more active sites and surface area for a catalytic reaction to take place. As-prepared SnS2/g-C3N4 also exhibited 90 % photocatalytic MB deterioration in 90 min upon solar irradiation, following first order kinetics. Type-II mechanism for charge transfer alongwith reactive specie trapping experiment and cyclic stability is also presented. The findings suggests that SnS2/g-C3N4 emerged as proficient catalyst for electrocatalytic and photocatalytic applications.

Hierarchical nanoflowers of Bi/Fe-based selenide as a bifunctional electrocatalyst for alkaline water electrolysis

The current study presents a freestanding bifunctional electrocatalyst comprising hierarchically assembled Bi/Fe-based selenide with a nanoflower-like morphology on Ni foam for water electrolysis application. The impact of systematically adding Fe ions to Bi2Se3 on the phase and morphology is elaborately discussed. It is shown that tuning the Bi/Fe molar ratio governs the phase, electronic bandgap, and morphology, driven by the evolution of hetero-interfacial chemistry. The existence of multivalent metal ions, lattice defects, and an extended surface area remarkably improves the electrocatalytic activity. The optimized nanoflower-like composite electrode (1Bi1Fe-Se@NF) exhibits robust electrocatalytic efficacy with extremely low overpotentials of ∼53 mV and ∼230 mV at 10 mA cm−2 for hydrogen and oxygen evolution reactions, respectively. The symmetrical alkaline electrolyser, utilizing 1Bi1Fe-Se@NF electrodes (+,−), operates at a cell voltage of ∼1.52 V at 10 mA cm−2, lower than the device equipped with commercial Pt/C@NF (-) and RuO2@NF (+) (∼1.57 V). Even after 100 h of operation at 50 mA cm−2, the symmetrical cell maintains a stable voltage, highlighting the outstanding bifunctional catalytic activities of noble metal-free 1Bi1Fe-Se@NF for overall water electrolysis.

Hierarchical Fusiform ZnO-Constructed Nanoflowers Electrodeposited on Stainless-Steel Mesh with Switchable Wettability for On-Demand Separation of Oil–Water Emulsion and Photocatalytic Degradation for Water-Soluble Pollutants

Hierarchical Fusiform ZnO-Constructed Nanoflowers Electrodeposited on Stainless-Steel Mesh with Switchable Wettability for On-Demand Separation of Oil–Water Emulsion and Photocatalytic Degradation for Water-Soluble Pollutants

Bandgap engineering of novel Cu-vanadate/g-C3N4 hierarchical nanoflowers for enhanced photodegradation and excellent biosensing capability

Copper vanadate and graphitic carbon nitride (g-C3N4) are pivotal materials in the realm of advanced materials science, owing to their distinctive optical and electronic conductive properties. In the context of environmental photocatalysis and biosensing applications, their synergistic combination holds significant promise. Copper vanadate, renowned for its optical and electronic properties, complements the unique architecture and optical conduction characteristics of g-C3N4. Together, these materials exhibit immense potential for driving advancements in environmental sustainability and diagnostic techniques. In this study, we report the synthesis of copper vanadate (Cu0.261V2O5) and its composite with graphitic carbon nitride. XRD confirms the synthesis of the novel phase, FESEM and TEM analysis reveals hierarchical nanoflowers and UV-Visible spectroscopy divulges the visible light activation of the synthesized material and aids in the calculation of the optical bandgap. Interfacial charge transfer was studied with the help of EIS and Mott-Schottky analysis was employed to reveal the semiconductor type (n or p type) and determine the band edges. The as-prepared material was tested for the photocatalytic removal of methylene blue (MB), followed by the study of reaction kinetics, cyclic stability and active radicals participating in the photocatalysis process. The synthesized heterojunction showed 100 % removal of MB within a tenure of 90 minutes. The results of the experiment revealed that Cu0.261V2O5 decorated with g-C3N4 displays 1.5 and 1.4 times better photocatalytic degradation capability than pure Cu0.261V2O5 and g-C3N4, respectively. Furthermore, the synthesized material was evaluated for electrochemical biosensing of ascorbic acid in PBS (pH 7) analyte using a 3-electrode system. Compared to the pure material, the heterojunctions drew 1.9 times more current and provided near unity correlation (R2). It is evident that Cu0.261V2O5 decorated with g-C3N4 can be implemented for commercial eco-remediation and electrochemical ascorbic acid sensing.

Phosphorus-doped nickel cobalt oxide (NiCo2O4) wrapped in 3D hierarchical hollow N-doped carbon nanoflowers as highly efficient bifunctional electrocatalysts for overall water splitting

Properly design and fabricate capable electrocatalysts with 3D hierarchical hollow framework to realize cost-effective and efficacious overall water splitting (OWS) are particularly meaningful for the large-scale arrangement of pivotal energy technology. In this study, P-doped NiCo2O4 nanoparticles encapsulated in N-doped carbon hierarchical hollow nanoflowers (P-NiCo2O4@NCHHNFs) were constructed using the hydrothermal-pyrolysis-phosphorization approach. This fascinating architecture can not merely serve as a conductive pathway for electron transfer, but at the same time effectively inhibited the aggregation and corrosion of the NiCo2O4 nanoparticles. Additionally, the P doping not only regulates electronic structure configuration to boost the intrinsic activity of the catalyst, but also enhance electrochemical surface areas to reveal more accessible active sites. Attributing to these characteristics, the as-prepared P-NiCo2O4@NCHHNFs exhibit preeminent electrocatalytic performance with low overpotentials of 283 mV and 162 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) (at 10 mA cm−2), respectively. Specifically, by using the P-NiCo2O4@NCHHNFs as bifunctional catalysts, a low potential of 1.56 V (at 10 mA cm−2) is sufficient to drive overall water splitting with splendid durability. This study proposed an innovative strategy for the conceiving and fabricating high-performance catalysts via heteroatom-doping.

Dual engineering of hetero-interfaces and architecture in MoSe2/VSe1.6@N[sbnd]C nanoflower for fast and stable sodium/potassium storage

Rational structure design is significant for the selenide anodes in the sodium/potassium ion batteries (SIBs/PIBs). Herein, dual engineering of hetero-interfaces and architecture is proposed to design SIB/PIB anodes. Attributed to the coordination binding with Mo7O246- and VO3-, the polydopamine assembly is demonstrated as an ideal template to produce bimetallic selenide of MoSe2/VSe1.6 anchoring on the in-situ N-doped carbon matrix (MoSe2/VSe1.6@NC). This ingenious hierarchical nanoflower structure can shorten the Na+/K+ diffusion length, increase the electron conductivity and buffer the volume changes, which can promote Na+/K+ reaction kinetics and stabilize the cycling performance. Consequently, the sodium/ potassium storage performance of MoSe2/VSe1.6@NC can be boosted. In SIBs, it achieves a capacity of 202 mAh/g at 10.0 A/g for 5000 cycles. Meanwhile, stable capacities of 207.1 mAh/g can be reached at 1.0 A/g over 1000 cycles in the PIBs. Furthermore, impressive capacities of 222.1 mAh/g and 100.4 mAh/g are delivered in the full cells of MoSe2/VSe1.6@NC//Na3V2(PO4)3@C and MoSe2/VSe1.6@NC//FePBA, respectively. This proves the potential practical application for the MoSe2/VSe1.6@NC anode in SIBs/PIBs.

Hierarchical NiFeP Nanoflowers on the MXene Film as a Self-Standing Bifunctional Electrode toward Superior Overall Water Electrolysis

Hierarchical NiFeP Nanoflowers on the MXene Film as a Self-Standing Bifunctional Electrode toward Superior Overall Water Electrolysis

S-scheme heterojunction and heterovalent ion doping synergistically promote the visible light photocatalytic performance of hierarchical nanoflowers

This study proposes a combined strategy of defect engineering and construction of S-scheme heterojunction that produces synergistic photovoltaic effects and significantly enhances photocatalysis degradation of organic pollutants under visible-light. A three-dimensional hierarchical flower-like photocatalyst CdS@Gd-ZnO featuring S-scheme heterojunction was rationally constructed. CdS@Gd-ZnO was able to degrade 99 % of rhodamine B (RhB) (10 mg/L, 75 min) and 95 % of methylene blue (MB) (10 mg/L, 60 min) under visible-light. Also, it has an excellent ability to degrade antibiotics, with 93 % of tetracycline hydrochloride (TCH) (20 mg/L, 60 min) and 90 % of oxytetracycline (OTC) (20 mg/L, 60 min), respectively. It was found that a small amount of Gd3+ doping was not only conducive to introducing more oxygen defects, which provides a powerful tool for trapping electrons for charge transfer, but also caused the change of energy band structure, and ultimately enhanced the degradation of cationic pollutants. Accordingly, this strategy enhances the photocatalytic performance of CdS@Gd-ZnO, and the combined effect is significantly stronger than either alone. This work provides a new idea for the design of efficient heterojunction photocatalysts for energy and environmental applications.

3D dendritic hierarchically gradient nanoflowers in situ grown on conductive substrates for efficient hydrovoltaic power generation

3D hierarchical porous TiO2 nanoflowers (HTNFs) with balanced selectivity and permeability for efficient water-droplet-induced hydrovoltaic power generators.

A self-assembled three-dimensional hierarchical nanoflower: an efficient enzyme-mimetic material for cancer cell detection that improves ROS generation for therapy.

Three-dimensional (3D) nanomaterials with high functional properties are emerging as the most promising artificial enzymes for overcoming the significant disadvantages of natural enzymes. Anticancer therapy using 3D-enzyme mimetic materials has emerged as an essential development for catalyzing cancer cell destruction. We report for the first time a novel 3D-based enzyme mimetic material, CaMoO4/MoS2/CuS nanoflower (CMC NF), that exhibits a large specific surface area, uniform flower-like structure, excellent biocompatibility, and high porosity, making it a suitable candidate for cancer detection and therapy. Additionally, CMC NFs were conjugated with folic acid (FA) to selectively target cancer cells, resulting in FA-CMC NFs explicitly binding to overexpressed folate receptor alpha (FRα) in MDA-MB-231 cells. Based on the peroxidase activity, the FA-CMC NFs are an effective nanoprobe for the selective detection of MDA-MB-231 cells over a wide detection range (50 to 5.5 × 104 cells per mL) with a low limit of detection (LOD) value of 10 cells per mL. In addition to their cancer detection capability, the FA-CMC NFs also effectively generated ˙OH radicals in a concentration-dependent manner to treat cancer cells. Under light conditions, the FA-CMC NFs with H2O2 solution showed efficient degradation of methylene blue (MB) dye, and the solution color appeared to fade within 15 min, indicating that they generated ˙OH radicals, which can efficiently kill cancer cells. Thus, the superior functionality of FA-CMC NFs offers cost-effective, facile, and reliable cancer cell detection, providing a new treatment option for cancer treatment and diagnosis.

Fabrication of three-dimension hierarchical structure CuO nanoflowers and their antifungal mechanism against Bipolaris sorokiniana

Nanomaterials are widely investigated in sustainable agriculture owing to their unique physicochemical properties, especially Cu-based nanomaterial with eco-friendliness and essential for plant. However, the effect of CuO nanomaterial on Bipolaris sorokiniana (B. sorokiniana) is yet to be systematically understood. In this study, a three-dimension hierarchical structure CuO nanoflower (CuO NF) with ultrathin petals and excellent dispersibility in water was constructed and proved to have outstanding antifungal activity against B. sorokiniana with the inhibition rate of 86 % in mycelial growth, 74 % in mycelial dry weight and 75 % in conidial germination. Furthermore, the antifungal mechanism was assigned to the production of reactive oxygen species in intracellular caused by antioxidant mimicking activity of CuO NF to damage of cell membrane integrity and result cellular leakage. Additionally, the good control effect of CuO NF on wheat diseases caused by B. sorokiniana was demonstrated through pot experiment. This article firstly reveals the antifungal activity and mechanism of CuO NF on B. sorokiniana, and establishes the relationship between enzyme-like activity of CuO NF and its antifungal activity, which provides a promising application of Cu-based nanomaterial as nanofungicide in plant protection and a theoretical foundation for structure design of nanomaterials to improve their antifungal activities.

Coordination polymer and layered double hydroxide dual-precursors derived polymetallic phosphides confined in N-doped hierarchical porous carbon nanoflower as a highly efficient bifunctional electrocatalyst for overall water splitting

Controllable construction of proficient electrocatalyst with 3D hierarchical architecture to achieve low cost and high efficient overall water splitting is of great significance to the sustainable development. Hereby, trimetallic phosphides confined in N-doped carbon nanoflowers (CoNiP/CoNiFeP@NCNFs) were fabricated using CoNi coordination polymer nanoflowers/CoNiFe layered double hydroxide (CoNi CPNFs/CoNiFe LDH) as precursors followed by phosphorization. Benefiting from the unique 3D hierarchical porous architecture, preeminent conductivity, high specific surface area, efficient mass/charge transfer and synergic effect of various transition metals, the well-designed CoNiP/CoNiFeP@NCNFs exhibit extraordinary electrocatalytic performance for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media. Particularly, this novel material can work as a bifunctional catalyst in an integrated water-splitting electrolyzer, which only requires a low voltage of 1.55 V to realize the current density of 10 mA cm−2 with admirable durability (at least 28 h). This work certified the foreground of composites assembled by 3D hierarchical porous carbon and polymetallic phosphides for overall water splitting. It also provided a novel proposal for the rational designing and constructing highly active electrocatalysts by using coordination polymer and LDH as dual-precursors.