Shape-controlled Nanoparticles Research Articles

Shape Dependent Therapeutic Potential of Nanoparticulate System: Advance Approach for Drug Delivery.

Drug delivery systems rely heavily on nanoparticles because they provide a targeted and monitored release of pharmaceuticals that maximize therapeutic efficacy and minimize side effects. To maximize drug internalization, this review focuses on comprehending the interactions between biological systems and nanoparticles. The way that nanoparticles behave during cellular uptake, distribution, and retention in the body is determined by their shape. Different forms, such as mesoporous silica nanoparticles, micelles, and nanorods, each have special properties that influence how well drugs are delivered to cells and internalized. To achieve the desired particle morphology, shape-controlled nanoparticle synthesis strategies take into account variables like pH, temperatures, and reaction time. Top-down techniques entail dissolving bulk materials to produce nanoparticles, whereas bottom-up techniques enable nanostructures to self-assemble. Comprehending the interactions at the bio-nano interface is essential to surmounting biological barriers and enhancing the therapeutic efficacy of nanotechnology in drug delivery systems. In general, drug internalization and distribution are greatly influenced by the shape of nanoparticles, which presents an opportunity for tailored and efficient treatment plans in a range of medical applications.

Direct measurement of the hydrogen adsorption entropy on shape-controlled Pt nanoparticles using electrochemical microcalorimetry

We measured the entropy of hydrogen adsorbed on Pt NPs with 3 different shapes. The entropy depends on the local geometry of the particles and matches the entropy of hydrogen adsorbed on single crystals with the corresponding orientation.

Nanozymes based on octahedral platinum nanocrystals with {111} surface facets: glucose oxidase mimicking activity in electrochemical sensors

The ability of shape-controlled octahedral Pt nanoparticles to act as nanozyme mimicking glucose oxidase enzyme is reported. Extended {111} particle surface facets coupled with a size comparable to natural enzymes and easy-to-remove citrate coating give high affinity for glucose, comparable to the enzyme as proven by the steady-state kinetics of glucose electrooxidation. The easy and thorough removal of the citrate coating, demonstrated by X-ray photoelectron spectroscopy analysis, allows a highly stable deposition of the nanozymes on the electrode. The glucose electrochemical detection (at −0.2 V vs SCE) shows a linear response between 0.36 and 17 mM with a limit of detection of 110 μM. A good reproducibility has been achieved, with an average relative standard deviation (RSD) value of 9.1% (n = 3). Similarly, a low intra-sensor variability has been observed, with a RSD of 6.6% (n = 3). Moreover, the sensor shows a long-term stability with reproducible performances for at least 2 months (RSD: 7.8%). Tests in saliva samples show the applicability of Pt nanozymes to commercial systems for non-invasive monitoring of hyperglycemia in saliva, with recoveries ranging from 92 to 98%.Graphical

(Invited) Recent Development of Electrochemical Nitrate Reduction

Understanding the complexities of nitrogen cycle is critical because when the cycle is not in balance, excess reduced and oxidized nitrogen compounds could result in harmful impacts to life. Electrocatalytic conversion of waste nitrate (NO3 -) to benign dinitrogen (N2) and ammonia (NH3) fuel is an appealing strategy that may easily integrate with renewable energy. The process does not require chemical addition and thus requires operating costs lower than thermal routes. Nearly all nitrogen-based fertilizers rely on ammonia as a feedstock, and thus the demand for this chemical is heavily dependent on the global population and food demand. Over the next three decades, the global population will continue to dictate the market size and value for ammonia, which consequently will have a significant impact on our energy infrastructure. While electrochemical nitrogen reduction reaction (NRR) requires multiple proton and electron transfer process, ammonia production from nitrate reduction (NO3RR) is catalytic easier than NRR because the adsorbed/activated ion reactants (nitrate and nitrite) have an advantage of a lower dissociation energy for the N−O and N=O bonds (204 and 607 kJ mol-1) than that of N≡N bond (941 kJ mol-1). The synergistic effect between Cu and Pd has shown a high nitrate conversion yield and nitrogen selectivity. Engineering the Pd and Cu sites is critical but examination of the use of secondary metals in shape-controlled nanoparticle and atomic reconstruction are rare.Here, we controlled Cu surface coverage on Pd nanocube nanoparticle to steer the selectivity between nitrogen and ammonia. In addition, the engineered the atomic structure of Pd and Cu nanoparticles showed high nitrate conversion yield, excellent dinitrogen selectivity, and outstanding cyclic stability. This study provides insights into the rational design of NO3RR electrocatalyst for efficiently transforming nitrate into nitrogen and ammonia.

Surfactant-assisted combustion synthesis of agglomerated-free, size- and shape-controlled magnetic iron oxide nanoparticles for biomedical applications

An advanced version of the solution combustion synthesis (SCS) method was developed to prepare iron oxide (IO) nanoparticles, through controlling the agglomeration, size and shape of nanoparticles by assisting a cationic surfactant, “cetyltrimethylammonium bromide (CTAB)” and ethanol. Various IO nanoparticles were prepared in the presence of different CTAB:ethanol molar compositions of 0:0, 0.27:0, 0.55:0, 0.27:17.1, 0.55:17.1 and 0.82:17.1. The morphological evolution from agglomerated-shape particles to the well-dispersed as well as the size- and shape-controlled particles depended directly on the CTAB:ethanol molar composition. A shift from ferromagnetic behavior to superparamagnetic was observed by the application of CTAB along with ethanol, where the lowest blocking temperature (Tb, 60 K), highest saturation magnetization (Ms, 83.5 emu g−1), zero coercivity and remanance magnetization were revealed for the particles prepared by CTAB:ethanol molar compositions of 0.55:17.1. These particles showed an acceptable specific absorption rate (SAR) value (320 W g−1) as well as no obvious hemolytic and cytotoxic effects. This work provides new insights into advancing the SCS method and thus controlling the morphology, size and shape of metal oxide nanoparticles.

Electroreduction of CO2 on Au(310)@Cu High-index Facets.

The chemical selectivity and faradaic efficiency of high-index Cu facets for the CO2 reduction reaction (CO2 RR) is investigated. More specifically, shape-controlled nanoparticles enclosed by Cu {hk0} facets are fabricated using Cu multilayer deposition at three distinct layer thicknesses on the surface facets of Au truncated ditetragonal nanoprisms (Au DTPs). Au DTPs are shapes enclosed by 12 high-index {310} facets. Facet angle analysis confirms DTP geometry. Elemental mapping analysis shows Cu surface layers are uniformly distributed on the Au {310} facets of the DTPs. The 7 nm Au@Cu DTPs high-index {hk0} facets exhibit a CH4 : CO product ratio of almost 10 : 1 compared to a 1 : 1 ratio for the reference 7 nm Au@Cu nanoparticles (NPs). Operando Fourier transform infrared spectroscopy spectra disclose reactive adsorbed *CO as the main intermediate, whereas CO stripping experiments reveal the high-index facets enhance the *CO formation followed by rapid desorption or hydrogenation.

Precision nanoengineering for functional self-assemblies across length scales.

As nanotechnology continues to push the boundaries across disciplines, there is an increasing need for engineering nanomaterials with atomic-level precision for self-assembly across length scales, i.e., from the nanoscale to the macroscale. Although molecular self-assembly allows atomic precision, extending it beyond certain length scales presents a challenge. Therefore, the attention has turned to size and shape-controlled metal nanoparticles as building blocks for multifunctional colloidal self-assemblies. However, traditionally, metal nanoparticles suffer from polydispersity, uncontrolled aggregation, and inhomogeneous ligand distribution, resulting in heterogeneous end products. In this feature article, I will discuss how virus capsids provide clues for designing subunit-based, precise, efficient, and error-free self-assembly of colloidal molecules. The atomically precise nanoscale proteinic subunits of capsids display rigidity (conformational and structural) and patchy distribution of interacting sites. Recent experimental evidence suggests that atomically precise noble metal nanoclusters display an anisotropic distribution of ligands and patchy ligand bundles. This enables symmetry breaking, consequently offering a facile route for two-dimensional colloidal crystals, bilayers, and elastic monolayer membranes. Furthermore, inter-nanocluster interactions mediated via the ligand functional groups are versatile, offering routes for discrete supracolloidal capsids, composite cages, toroids, and macroscopic hierarchically porous frameworks. Therefore, engineered nanoparticles with atomically precise structures have the potential to overcome the limitations of molecular self-assembly and large colloidal particles. Self-assembly allows the emergence of new optical properties, mechanical strength, photothermal stability, catalytic efficiency, quantum yield, and biological properties. The self-assembled structures allow reproducible optoelectronic properties, mechanical performance, and accurate sensing. More importantly, the intrinsic properties of individual nanoclusters are retained across length scales. The atomically precise nanoparticles offer enormous potential for next-generation functional materials, optoelectronics, precision sensors, and photonic devices.

Self-reduction of bimetallic nanoparticles on flexible MXene-graphene electrodes for simultaneous detection of ascorbic acid, dopamine, and uric acid

Three-dimensional (3D) porous laser-scribed graphene (LSG) is a potential electrode material for flexible electrochemical sensors due to its high efficiency and low cost. However, the growth of nanoparticles usually depends on reducers or harsh conditions, which limit the application of flexible biosensors. To resolve this issue, 2D MXene nanosheets were applied to functionalize 3D LSG sheets with a C-O-Ti covalent crosslink and obtain an LSG-MXene hybrid scaffold. The shape-controlled Au-Pd bimetallic nanoparticles were synthesized on the surface of LSG-MXene by a self-reduction process at room temperature for 6 min to enhance its catalytic performance. As a proof of concept, the obtained hybrid nanocomposite was used to assess ascorbic acid (AA, 10–1600 μM), dopamine (DA, 12–240 μM), and uric acid (UA, 8–100, 200–800 μM). The fabricated sensor exhibited a low detection limit (S/N = 3) of 3 μM AA, 0.13 μM DA, and 1.47 μM UA. Furthermore, the Au-Pd/MXene/LSG was successfully applied to determine AA, DA, and UA in urine samples. Predictably, these outstanding performance sensors have great potential in flexible and wearable electronics.

In Situ Assembly of Well-Defined MoS2 Slabs on Shape-Tailored Anatase TiO2 Nanostructures: Heterojunctions Role in Phenol Photodegradation

MoS2/TiO2-based nanostructures have attracted extensive attention due to their high performance in many fields, including photocatalysis. In this contribution, MoS2 nanostructures were prepared via an in situ bottom-up approach at the surface of shape-controlled TiO2 nanoparticles (TiO2 nanosheets and bipyramids). Furthermore, a multi-technique approach by combining electron microscopy and spectroscopic methods was employed. More in detail, the morphology/structure and vibrational/optical properties of MoS2 slabs on TiO2 anatase bipyramidal nanoparticles, mainly exposing {101} facets, and on TiO2 anatase nanosheets exposing both {001} and {101} facets, still covered by MoS2, were compared. It was shown that unlike other widely used methods, the bottom-up approach enabled the atomic-level growth of well-defined MoS2 slabs on TiO2 nanostructures, thus aiming to achieve the most effective chemical interactions. In this regard, two kinds of synergistic heterojunctions, namely, crystal face heterojunctions between anatase TiO2 coexposed {101} and {001} facets and semiconductor heterojunctions between MoS2 and anatase TiO2 nanostructures, were considered to play a role in enhancing the photocatalytic activity, together with a proper ratio of (101), (001) coexposed surfaces.

Promoting effects of residual poly(vinyl alcohol) capping agent on the activity and chemoselectivity of Pt/Al2O3 for catalytic hydrogenation

Capping agents are key to the colloidal synthesis of size- and shape-controlled nanoparticles (NPs) for catalysis. The capping agents on the NP surface are generally removed after synthesis to expose the catalytically active sites. However, the total removal of the capping agents results in the loss of the ability of the capped NPs to regulate the adsorption mode of the reactants, which can, in some cases, decrease selectivity. Here, poly(vinyl alcohol) (PVA)-capped Pt/Al2O3 are prepared and the amount of PVA capping agent remaining on the NP surfaces is controlled by heat treatment to take full advantage of capped NPs. Compared to a surface-clean Pt catalyst, those covered in PVA residues having partially exposed metal sites show enhanced activity and selectivity for the hydrogenation of acetophenone to 1-phenylethanol. Detailed characterization reveals that the promoting effects of the residual PVA are attributed to the combined contributions of electronic modification of the Pt surface, selective exposure of highly active Pt defect sites, and steric hindrance with the aromatic ring of acetophenone. This study offers insights into the roles of residual capping agents in heterogeneous catalysis and provides a new strategy for enhancing the performance of nanocatalysts using capped NPs.

Editorial Overview: Nanoscale Electrochemistry

A central challenge in electrochemical sciences is that the electrochemical response of an electrode is dominated by nanoscale features on the surface, yet our traditional electrochemical techniques operate on a millimeter or greater length scales. For instance, when we make a cyclic voltammetry measurement on a millimeter-scale electrode, the signal we obtain is based on the average response of all the active sites across the surface while details such as the activities of each site, their spatial distribution, and dynamics cannot be revealed. Nanoscale electrochemistry raises this challenge and has developed a range of techniques to effectively “zoom in” to the micro or nanoscale and, ultimately, to single molecules and atoms, enabling precise measurement of dynamic electrochemical process. This special edition highlights the cutting edge of nanoscale electrochemical research, spanning nanoparticle structure-activity relationships to DNA sequencing and 3D printing. A mainstay of modern nanoscale electrochemistry is the scanning droplet approach known as scanning electrochemical microscopy (SECCM). SECCM simply and effectively restricts an electrochemical measurement to micro or nanoscale region of a large sample surface. In this special edition (Table 1), Schuhmann and co-workers use SECCM to investigate the structure-activity relationships in a high entropy alloy and reveal that active site-specific activities can be detected with probes of dimensions below a micrometer.[1] Takahashi and coworkers use SECCM to investigate the capacitive response of carbon surfaces with 100-nanometer resolution and evaluate the difference in degradation of HOPG occurring at the edge and basal planes.[2] Caleb and co-workers apply a targeted electrochemical cell microscopy (TECCM) approach to isolate the electrocatalytic response of individual shape-controlled nanoparticles toward borohydride oxidation and reveal the significant variations in reactivity and stability for individual nanoparticles.[3] In the review by Bentley, the author summarizes how SECCM has been used to study (nano)particle electrochemistry, often isolated single nanoparticles dispersed on inert supports, and sometimes at sub-particles level.[4] Finally, Momotenko and coworkers review how scanning probe approaches, including but not limited to SECCM, can be utilized for micro and nanoscale electrochemical 3D printing, an innovative strategy for precise fabrication of micro and nanoscale structures.[5] A different approach of electrochemical measurements at nanointerfaces is nano-collision or nano-impact electrochemistry. Shen and Wang demonstrate three different configurations to investigate the size, surface charge, dielectric properties, and electrochemical features of individual graphene oxide sheets.[6] Another approach towards nanoscale electrochemistry is the advanced optical microscopy, where electrochemical processes at nanointerfaces can be imaged with high spatial and temporal resolution by detecting local optical properties. Willets and Bohn investigate the potential-dependent luminescence emission from three different electrofluorogenic probes an indium-tin oxide (ITO) surface.[7] A counterintuitive spectroelectrochemical observation at high irradiance or at low concentration is reported, highlighting the largely ignored importance of interaction between electrofluorogenic probes and ITO surfaces. Finally, we have two opinions that highlight how conductometric electrochemical sensors that make use of nanopores can effectively enable accurate measurements to single molecules. Tan and Ming review how biological nanopores can be used to detect nucleobase modifications in DNA,[8] while Johnson and co-workers elaborate how this approach can be used to sequence double-stranded DNA.[9] To summarize, nanoscale electrochemistry will continue to advance at space and time, revealing the intrinsic features that are often buried and gaining more complete understanding of intricate electrochemical process. Finally, we would like to express our thanks to the Publisher Dr. Brian P. Johnson and Editorial Manager Dr. Jing Tang for their kind supports during the preparation of this special edition. The authors declare no conflict of interest.

Decoupling the electronic and geometric effects of Pt catalysts in selective hydrogenation reaction

Decoupling the electronic and geometric effects has been a long cherished goal for heterogeneous catalysis due to their tangled relationship. Here, a novel orthogonal decomposition method is firstly proposed to settle this issue in p-chloronitrobenzene hydrogenation reaction on size- and shape-controlled Pt nanoparticles (NPs) carried on various supports. Results suggest Fermi levels of catalysts can be modulated by supports with varied work function (Wf). And the selectivity on Pt NPs of similar size and shape is linearly related with the Wf of support. Optimized Fermi levels of the catalysts with large Wf weaken the ability of Pt NPs to fill valence electrons into the antibonding orbital of C–Cl bond, finally suppressing the hydrodehalogenation side reaction. Foremost, the geometric effect is firstly spun off through orthogonal relation based on series of linear relationships over various sizes of Pt NPs reflecting the electronic effect. Moreover, separable nested double coordinate system is established to quantitatively evaluate the two effects.

Observation of Dominant Nuclei and Magic-Sized CdS Nanoparticles in a Single-Phase System.

Cadmium sulfide nanoparticles (CdS NPs) were synthesized by using cadmium acetate and thiourea as precursors and sodium oleate as the surfactant under different cadmium acetate concentrations in anhydrous ethanol. Cadmium (Cd) precursor concentration greatly affected the nucleation-growth of CdS NPs. In extremely dilute solution with a Cd precursor concentration of 0.1 mmol · L-1, an overlapped nucleation and growth corresponding to two pronounced absorption peaks at 310 nm and 350 nm, respectively, was observed. Unparalleled nucleation was dominant within very long reaction time until 10 hours. The nuclei and the resulting magic-sized CdS NPs may be used as seeds to prepare size and shape controllable nanoparticles. On the contrary, at a high Cd precursor concentration (5 mmol · L-1), nucleation and growth were separated. Only one first exciton absorption peak standing for the growth of regular CdS NPs appeared at 440 nm. Many techniques including transmission electron microscopy (TEM), X-ray powder diffraction (XRD), ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectrometers were applied to characterize the morphology, crystalline structure, and optical properties of CdS NPs.

Soft matter: Shape control at the nanoscale despite amorphousness

Nanoscale engineering of shapes is a complex process. Can shapes of the soft nanoparticles be controlled by mechanical force or other means? While shape-controlled metal nanostructures are being developed, little success is realized in the case of shape-controlled polymer nanoparticles.

Managing the Nitrogen Cycle via Plasmonic (Photo)Electrocatalysis: Toward Circular Economy.

As renewable energy sources are either intermittent in nature or remote in location, developing cost-effective, sustainable, modular systems and technologies to store and transport renewables at an industrial scale is imperative. Storing cheap renewable electricity into chemical bonds (i.e., chemical energy storage) could be a transformative opportunity for reliable and resilient grid energy storage. This approach enables renewables to be stored and shipped similarly to fossil fuels. Currently, the chemical industry primarily consumes fossil feedstock as an energy source, which has been the standard for over a century. A paradigm shift is required to move toward a more sustainable route for chemical synthesis by electrifying and decarbonizing the modern chemical industry. As renewable electricity costs decrease, (photo)electrosynthesis is gaining interest for synthesizing high-value and high-energy fuels and molecules in a clean, sustainable, and decentralized manner.The nitrogen cycle is one of the Earth's most critical biogeochemical cycles since nitrogen is a vital element for all living organisms. Artificial nitrogen fixation via a (photo)electrochemical system powered by renewables provides an alternative route to resource- and carbon-intensive thermochemical processes. (Photo)electrochemical nitrogen fixation at a large scale necessitates the discovery of active, selective, and stable heterogeneous (photo)electrocatalysts. In addition, the use of advanced in situ and operando spectroscopic techniques is needed to pinpoint the underlying reaction mechanisms. The selectivity of nitrogen (N2) molecules on the catalyst surface and suppressing thermodynamically favorable side reactions (e.g., hydrogen evolution reaction) are the main bottlenecks in improving the rate of (photo)electrochemical nitrogen fixation in aqueous solutions. The rational design of electrode, electrolyte, and reactors is required to weaken the strong nitrogen-nitrogen triple bond (N≡N) at or near ambient conditions. This Account covers our group's recent advances in synthesizing shape-controlled hybrid plasmonic nanoparticles, including plasmonic-semiconductor and plasmonic-transition metal nanostructures with increased surface areas. The nanocatalysts' selectivity and activity toward nitrogen conversion are benchmarked in liquid- and gas-phase electrochemical systems. We leverage operando vibrational-type spectroscopy (i.e., surface-enhanced Raman spectroscopy (SERS)) to identify intermediate species relevant to nitrogen fixation at the electrode-electrolyte interface to gain mechanistic insights into reaction mechanisms, leading to the discovery of more efficient catalysts. Operando SERS revealed that the nitrogen reduction reaction (NRR) to ammonia on hybrid plasmonic-transition metal nanoparticle surfaces (e.g., Pd-Ag) occurs through an associative mechanism. In the NRR process, hydrazine (N2H4) is consumed as an intermediate species. A femtosecond pulsed laser is used to synthesize hybrid plasmonic photocatalysts with homogeneously distributed Pd atoms on a Au nanorod surface, resulting in enhanced optoelectronic and catalytic properties. The overarching goal is to develop modular photoelectrochemical systems for long-duration renewable energy storage. In the context of nitrogen fixation, we aim to propose strategies to manage the nitrogen cycle through the interconversion of N2 and active nitrogen-containing compounds (e.g., NH3, NOx), enabling a circular nitrogen economy with sustainable and positive social and economic outcomes. The versatile approaches presented in this Account can inform future opportunities in (photo)electrochemical energy conversion systems and solar fuel-based applications.

Effect of Electrolyte Contaminants and Surface Roughness on the Constant Phase Element

The origin of constant phase element (CPE) to explain electrode/electrolyte interface is subject of debate in the literature. CPE behavior is generally attributed to the presence of reactivity, surface inhomogeneity, various crystal planes and atomic scale defects in the crystal; all these may lead to dispersion of local capacitance at the electrode/electrolyte interface. Therefore, electrode/electrolyte interface of polycrystalline Pt (Pt-PC) and smooth glassy carbon disk electrode (GCE) are investigated in ultra-pure H2SO4 (0.5 M) electrolyte[1]. The surface of GCE is roughened mechanically to test the effect of roughness. The effect of intentional and unintentional contaminants are investigated using halide (Cl˗, Br-, I-) ions[2]. It is found that the CPE is affected by the concentration and nature of anion in the electrolyte. Unintentional impurities and cations do not affect the CPE behavior.[1] Singh, R. K., Devivaraprasad, R., Kar, T., Chakraborty, A., & Neergat, M. (2015). Electrochemical impedance spectroscopy of oxygen reduction reaction (ORR) in a rotating disk electrode configuration: effect of ionomer content and carbon-support. Journal of The Electrochemical Society, 162(6), F489.[2] Devivaraprasad, R., Ramesh, R., Naresh, N., Kar, T., Singh, R. K., & Neergat, M. (2014). Oxygen reduction reaction and peroxide generation on shape-controlled and polycrystalline platinum nanoparticles in acidic and alkaline electrolytes. Langmuir, 30(29), 8995-9006. Figure 1

Electrochemical Reduction of CO2 on Au Electrocatalysts Under Commercially Relevant Condition

Much effort has been devoted for development of effective catalysts for the electrochemical reduction of CO2 (CO2RR). For CO2RR, performing H-cell experiments is the most common catalyst screening method where the reactant CO2 gas is usually dissolved in an aqueous bicarbonate-based electrolyte1. However, the low solubility of CO2 in aqueous solutions (∼35 mM at 298 K and 1 atm pressure) causes mass transport limitations when using dissolved CO2 as the reactant. Based on H-cell measurements gold (Au) is one of the most selective catalysts for CO2RR to CO2. However, preparation of shape-controlled Au nanoparticles (NPs) based on conventional synthesis methods requires the use of surfactants and capping agents such as polyvinylpyyrolidone (PVP). Here, we report the electroreduction of CO2 on ligand-free Au NPs (Au-PVP-free NPs) and Au NPs with PVP (Au-PVP NPs) that were produced by laser ablation3. For this purpose, we used our recently introduced gas diffusion electrode (GDE) setup1 which supplies a continuous CO2 stream at the electrode−electrolyte interface to circumvent CO2 mass transport limitations of the conventional liquid cells4. Moreover, we performed same experiments in the H-cell setup to compare between these two screening methods. In both measurement setups, the presence of PVP favors hydrogen evolution reaction (HER). However, we also observed differences in performance of the same catalyst at same experimental conditions in these two setups, which highlights the importance of having commercially relevant conditions for catalyst screening.Finally, we investigated the influence of different binders and membranes on selectivity and activity of Au-PVP-free NPs that led to more robust electrodes performance for CO2RR. Figure 1

Shape-Controlled Nanoparticles from a Low-Energy Nanoemulsion.

Nanoemulsion technology enables the production of uniform nanoparticles for a wide range of applications. However, existing nanoemulsion strategies are limited to the production of spherical nanoparticles. Here, we describe a low-energy nanoemulsion method to produce nanoparticles with various morphologies. By selecting a macro-RAFT agent (poly(di(ethylene glycol) ethyl ether methacrylate-co-N-(2-hydroxypropyl) methacrylamide) (P(DEGMA-co-HPMA))) that dramatically lowers the interfacial tension between monomer droplets and water, we can easily produce nanoemulsions at room temperature by manual shaking for a few seconds. With the addition of a common ionic surfactant (SDS), these nanoscale droplets are robustly stabilized at both the formation and elevated temperatures. Upon polymerization, we produce well-defined block copolymers forming nanoparticles with a wide range of controlled morphologies, including spheres, worm balls, worms, and vesicles. Our nanoemulsion polymerization is robust and well-controlled even without stirring or external deoxygenation. This method significantly expands the toolbox and availability of nanoemulsions and their tailor-made polymeric nanomaterials.

Effective design of MnO2 nanoparticles embedded in laser-induced graphene as shape-controllable electrodes for flexible planar microsupercapacitors

Flexible planar microsupercapacitors (MSCs), with the advantages of small size, easy integration and expansion on electronic devices, have emerged as one of the most critical power devices in wearable and portable electronics. However, most processes involve independent preparation of electrode materials, patterned microelectrodes, and subsequent modular integration, making the steps very complicated. Herein, we have developed a novel, simple and one-step laser direct writing process to design planar shape-controllable MnO2 nanoparticles evenly embedded in laser-induced graphene (MnO2/LIG) MSCs on different flexible substrates. The obtained MnO2/LIG MSCs show an outstanding areal specific capacity of 15.04 mF cm−2, a high energy density of 1.22 mWh cm−2 at a good power density of 1.278 mW cm−2, good mechanical flexibility and remarkable modular integration due to effective design of pseudocapacitive MnO2 nanoparticles evenly embedded in highly conductive LIG with 3D porous structure. This universal manufacturing route for controllable assembly of flexible planar MSCs with other pseudocapacitive nanoparticles embedded into LIG, thus broadening their flexible and wearable application as a promising storage device to meet the modular integration and biocompatibility.

Diclofenac degradation based on shape-controlled cuprous oxide nanoparticles prepared by using ionic liquid.

Persulfate oxidation technology is widely used in wastewater treatment, but there are still many disadvantages, such as high energy consumption, side reaction and narrow pH applicability. Copper oxides can activate persulfate steadily with higher efficiency. In this paper, a novel preparation method of shape-controlled cuprous oxide (Cu2O) nanoparticles featured with high catalytic performance was explored. It was found that adding ionic liquid 1-butyl-3-methylimidazolium bromide ([BMIM]Br) during preparation of Cu2O can improve the degradation rate of diclofenac (DCF). Cu2O nanoparticles possess good stability in consecutive cycling tests, which was confirmed by X-ray photoelectron spectroscopy. The possible mechanism of Cu2O activating persulfate at different initial pH conditions was discussed based on electron paramagnetic resonance spin-trapping experiment. It was found that DCF was efficiently degraded in the Cu2O/peroxydisulfate (PDS) system within a broad pH range from 5 to 11. It proved via a quenching experiment that the activation process of PDS mainly occurs on the surface layer of Cu2O nanoparticles. As a result, shape-controlled Cu2O nanoparticles prepared by ionic liquid are expected to be used for in situ chemical oxidation, which is an effective oxidation processes to degrade DCF remaining in surface water and ground water.