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Low-cost detection systems are needed for the identification of microplastics (MPs) in environmental samples. However, their rapid identification is hindered by the need for complex isolation and pre-treatment methods. This study describes a comprehensive sensing platform to identify MPs in environmental samples without requiring independent separation or pre-treatment protocols. It leverages the physicochemical properties of macroporous-mesoporous silver (Ag) substrates templated with self-assembled polymeric micelles to concurrently separate and analyze multiple MP targets using surface-enhanced Raman spectroscopy (SERS). The hydrophobic layer on Ag aids in stabilizing the nanostructures in the environment and mitigates biofouling. To monitor complex samples with multiple MPs and to demultiplex numerous overlapping patterns, we develop a neural network (NN) algorithm called SpecATNet that employs a self-attention mechanism to resolve the complex dependencies and patterns in SERS data to identify six common types of MPs: polystyrene, polyethylene, polymethylmethacrylate, polytetrafluoroethylene, nylon, and polyethylene terephthalate. SpecATNet uses multi-label classification to analyze multi-component mixtures even in the presence of various interference agents. The combination of macroporous-mesoporous Ag substrates and self-attention-based NN technology holds potential to enable field monitoring of MPs by generating rich datasets that machines can interpret and analyze., (© 2024. The Author(s).)

Ultrathin MXene-based films exhibit superior conductivity and high capacitance, showing promise as electrodes for flexible supercapacitors. This work describes a simple method to enhance the performance of MXene-based supercapacitors by expanding and stabilizing the interlayer space between MXene flakes while controlling the functional groups to improve the conductivity. Ti 3 C 2 T x MXene flakes are treated with bacterial cellulose (BC) and NaOH to form a composite MXene/BC (A-M/BC) electrode with a microporous interlayer and high surface area (62.47 m 2 g -1 ). Annealing the films at low temperature partially carbonizes BC, increasing the overall electrical conductivity of the films. Improvement in conductivity is also attributed to the reduction of -F, -Cl, and -OH functional groups, leaving -Na and -O functional groups on the surface. As a result, the A-M/BC electrode demonstrates a capacitance of 594 F g -1 at a current density of 1 A g -1 in 3 M H 2 SO 4 , which represents a ∼2× increase over similarly processed films without BC (309 F g -1 ) or pure MXene (298 F g -1 ). The corresponding device has an energy density of 9.63 Wh kg -1 at a power density of 250 W kg -1 . BC is inexpensive and enhances the overall performance of MXene-based film electrodes in electronic devices. This method underscores the importance of functional group regulation in enhancing MXene-based materials for energy storage.

The gold layer on the surface plasmon resonance (SPR) sensor chip cannot detect small molecules, such as glucose without the use of specific receptors. Metal-organic frameworks (MOFs) are useful in biosensing technologies for capturing and co-localizing enzymes and receptors with the target biomolecule. In many previous studies, the properties of the MOFs were often ignored, with these studies focusing on the selection of appropriate receptors. To take advantage of the unique properties of MOFs in biosensors, one must also consider the technique and transducer used because these aspects will strongly influence the detection mechanism. In this work, we have investigated for the first time, the applications of hierarchical metal-BDC (M-BDC) MOFs for glucose detection using the SPR technique without the use of specific receptors. The underlying interactions and adsorption mechanisms were analyzed using adsorption isotherm and kinetic models. The sensing measurements show that the SPR chips functionalized with M-BDC MOFs exhibit higher sensitivity and lower limit of detection (LOD). Specifically, the sensitivity follows the order of Zr-BDC > Cu-BDC > Mn-BDC > Ni-BDC > bare Au SPR chips with the LOD in the order of Zr-BDC < Mn-BDC < Ni-BDC < Cu-BDC < bare Au SPR chips. The selectivity test results reveal that Zr-BDC exhibits a decent selectivity to glucose in the presence of other interfering compounds, such as ascorbic acid, uric acid, maltose, and urea. These results demonstrate the promising potential of MOFs for SPR biosensing.

The photoreduction of carbon dioxide (CO 2 ) into renewable synthetic fuels is an attractive approach for generating alternative energy feedstocks that may compete with and eventually displace fossil fuels. However, it is challenging to accurately trace the products of CO 2 photoreduction on account of the poor conversion efficiency of these reactions and the imperceptible introduced carbon contamination. Isotope-tracing experiments have been used to solve this problem, but they frequently yield false-positive results because of improper experimental execution and, in some cases, insufficient rigor. Thus, it is imperative that accurate and effective strategies for evaluating various potential products of CO 2 photoreduction are developed for the field. Herein, we experimentally demonstrate that the contemporary approach toward isotope-tracing experiments in CO 2 photoreduction is not necessarily rigorous. Several examples of where pitfalls and misunderstandings arise, consequently making isotope product traceability difficult, are demonstrated. Further, we develop and describe standard guidelines for isotope-tracing experiments in CO 2 photoreduction reactions and then verify the procedure using some reported photoreduction systems., (© 2023. The Author(s).)

High-quality emission centers in two-dimensional materials are promising components for future photonic and optoelectronic applications. Carbon-enriched hexagonal boron nitride (hBN:C) layers host atom-like color-center (CC) defects with strong and robust photoemission up to room temperature. Placing the hBN:C layers on top of Ag triangle nanoparticles (NPs) accelerates the decay of the CC defects down to 46 ps from their reference bulk value of 350 ps. The ultrafast decay is achieved due to the efficient excitation of the plasmon modes of the Ag NPs by the near field of the CCs. Simulations of the CC/Ag NP interaction show that higher Purcell values are expected, although the measured decay of the CCs is limited by the instrument response. The influence of the NP thickness on the Purcell factor of the CCs is analyzed. The ultrafast operation of the CCs in hBN:C layers paves the way for their use in demanding applications, such as single-photon emitters and quantum devices., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Amorphous noble metals with high surface areas have attracted significant interest as heterogeneous catalysts due to the numerous dangling bonds and abundant unsaturated surface atoms created by the amorphous phase. However, synthesizing amorphous noble metals with high surface areas remains a significant challenge due to strong isotropic metallic bonds. This paper describes the first example of a mesoporous amorphous noble metal alloy [iridium-tellurium (IrTe)] obtained using a micelle-directed synthesis method. The resulting mesoporous amorphous IrTe electrocatalyst exhibits excellent performance in the electrochemical N 2 reduction reaction. The ammonia yield rate is 34.6 μg mg -1 h -1 with a Faradaic efficiency of 11.2% at -0.15 V versus reversible hydrogen electrode in 0.1 M HCl solution, outperforming comparable crystalline and Ir metal counterparts. The interconnected porous scaffold and amorphous nature of the alloy create a complementary effect that simultaneously enhances N 2 absorption and suppresses the hydrogen evolution reaction. According to theoretical simulations, incorporating Te in the IrTe alloy effectively strengthens the adsorption of N 2 and lowers the Gibbs free energy for the rate-limiting step of the electrocatalytic N 2 reduction reaction. Mesoporous chemistry enables a new route to achieve high-performance amorphous metalloid alloys with properties that facilitate the selective electrocatalytic reduction of N 2 .

The aim of shape-controlled colloidal synthesis of gold (Au) is to produce Au nanoparticles (NPs) with fine control of shapes, sizes, and dispersities. We show how transient absorption spectroscopy (TAS) can be used to rapidly and accurately quantify the vast ensemble of shapes of Au NPs in solution within minutes, including the synthesized nanorods, decahedra, and nanospheres. Colloidal solutions containing Au NPs were measured in TAS and their localized surface plasmon resonance (LSPR) modes were classified according to the shape, wavelength and number of peaks. Then their excited-state relaxation dynamics were used to ascertain their electron-phonon (e-ph) coupling time constant and frequency of optomechanical modes. TAS can quickly show that an Au nanosphere sample contains a tiny fraction of Au nanorods, whereas steady-state absorbance is totally blind to the presence of nanorods. Additionally, the TAS experiments indicate that the characteristic e-ph coupling time constants in Au nanorods depend on the NPs dimensions at high excitation intensity (> 6 µJ/cm 2 ) which can help identify if there are any elongated Au NPs in Au spheres samples. Finally, optomechanical oscillations formed by NPs breathing modes were observed, providing information related to the average size and monodispersity of Au nanospheres and nanorods.

As a typical battery-type material, CuCo 2 S 4 is a promising candidate for supercapacitors due to the high theoretical specific capacity. However, its practical application is plagued by inherently sluggish ion diffusion kinetics and inferior electrical transport properties. Herein, sulfur vacancies are incorporated in CuCo 2 S 4 hollow nanoarchitectures (HNs) to accelerate redox reactivity. Experimental analyses and theoretical investigations uncover that the generated sulfur vacancies increase the active electron states, reduce the adsorption barriers of electrolyte ions, and enrich reactive redox species, thus achieving enhanced electrochemical performance. Consequently, the deficient CuCo 2 S 4 with optimized vacancy concentration presents a high specific capacity of 231 mAh g -1 at 1 A g -1 , a ≈1.78 times increase compared to that of pristine CuCo 2 S 4 , and exhibits a superior rate capability (73.8% capacity retention at 20 A g -1 ). Furthermore, flexible solid-state asymmetric supercapacitor devices assembled with the deficient CuCo 2 S 4 HNs and VN nanosheets deliver a high energy density of 61.4 W h kg -1 at 750 W kg -1 . Under different bending states, the devices display exceptional mechanical flexibility with no obvious change in CV curves at 50 mV s -1 . These findings provide insights for regulating electrode reactivity of battery-type materials through intentional nanoarchitectonics and vacancy engineering., (© 2021 Wiley-VCH GmbH.)

Carbon nanoarchitectures derived from biobased building blocks are potential sustainable alternatives to electrode materials generated with petroleum-derived resources. We aim at developing a fundamental understanding on the connection between the structure and electrochemical performance of porous carbon nanofiber (PCNF) architectures from the polysaccharide chitosan as a biobased building block. We fabricated a range of PCNF architectures from the chitosan carbon precursor and tailored their structure by varying the amount and molecular weight of the sacrificial pore-forming polymer poly(ethylene oxide). The morphology (high-resolution scanning electron microscopy), carbon structure (X-ray diffraction, transmission electron microscopy), pore network (N 2 gas adsorption, small-angle X-ray scattering), and surface/bulk composition (X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy) were studied in detail together with a comprehensive electrochemical analysis on the fabricated electrodes. In supercapacitor devices, the best-performing freestanding electrode had (1) a high accessible surface area ( a s,BET ≈ 700 m 2 g -1 ) and hierarchical pore network (micro- and mesopores) providing a fast ion diffusion process, high specific capacitance, and rate capability, (2) surface chemistry allowing a high Coulombic efficiency by avoiding parasitic Faradaic side reactions, and (3) a unique turbostratic carbon nanostructure leading to low charge transfer resistance while keeping good electrical conductivity. This electrode exhibited good stability over 2000 cycles (at 2 A g -1 ) with high capacitance retention (>80%) and charge efficiency (>90%). In the capacitive deionization (CDI) device, our electrode demonstrated an ultrahigh salt adsorption capacity of 23.6 mg g -1 , which is among the state-of-the-art values reported for a biobased carbon. A high charge efficiency (85%) was achieved during the CDI process using low-cost materials, in contrast to similarly performing devices fabricated with expensive ion exchange membranes or petroleum-based carbon precursors. Our results demonstrate that inexpensive chitosan-based materials can be readily transformed in one carbonization step without any aggressive activating chemicals into tailor-made hierarchically ordered state-of-the-art carbon materials for charge storage devices.

Metal-organic frameworks (MOFs) and their derivatives are promising materials for energy conversion and storage. This study demonstrates a solvent-free method to fabricate a CoO x /carbon composite array derived from ZIF-67 for asymmetric supercapacitors. Tree-like Co metal arrays are electrodeposited on a surface and then directly converted into composite ZIF-67/Co-based MOF arrays via a chemical vapor deposition method (MOF-CVD). Finally, the CoO x /carbon composite array is obtained by regulated calcination of the ZIF-67/Co composite array. The as-prepared CoO x /carbon composite arrays provide a less tortuous pathway for ion diffusion, high pseudocapacitance from transition-metal oxides, and good electrical conductivity from carbon. Moreover, the absence of adhesives in array electrodes is also beneficial to the promotion of the electrochemical performance. The as-fabricated CoO x /carbon composite array electrode shows excellent electrochemical performance with high energy density, high power density, superior rate capability, and long cycle life in an asymmetric supercapacitor. These MOF-derived composite arrays are promising candidate materials for power sources because of their good electrochemical performance.

Numerous laboratories have observed random lasing from optically pumped solutions of plasmonic nanoparticles (NPs) suspended with organic dye molecules. The underlying mechanism is typically attributed to the formation of closed-loop optical cavities enabled by the large local field and scattering enhancements in the vicinity of plasmonic NPs. In this manuscript, we propose an alternative mechanism that does not directly require the plasmon resonance. We used high-speed confocal microspectroscopy to observe the photophysical dynamics of NPs in solution. Laser pulses induce the formation of microbubbles that surround and encapsulate the NPs, then sharp peaks <1.0 nm are observed that match the spectral signature of random lasing. Electromagnetic simulations indicate that ensembles of microbubbles may form optical corral containing standing wave patterns that are sufficient to sustain coherent optical feedback in a gain medium. Collectively, these results show that ensembles of plasmonic-induced bubbles can generate optical feedback and random lasing.

Bixbyite α -Mn 2 O 3 is an inexpensive Earth-abundant mineral that can be used to drive both oxygen evolution (OER) and oxygen reduction reactions (ORR) in alkaline conditions. It possesses a subtle orthorhombic → cubic phase change near room temperature that suppresses Jahn-Teller distortions and presents a unique opportunity to study how atomic structure affects the electronic structure and catalytic activity at a temperature range that is easily accessible in OER/ORR experiments. Previously, we observed that heat-treated α -Mn 2 O 3 had a better performance as a bifunctional catalyst in the oxygen evolution (OER) and oxygen reduction reactions (ORR) ( Dalton Trans . 2016, 45, 18,494-18,501). We hypothesized that heat-treatment pinned the material into a more electrochemically active cubic phase. In this manuscript, we use high-resolution X-ray diffraction to collect the temperature-dependent structures of α -Mn 2 O 3 , and then input them into ab initio calculations. The electronic structure calculations indicate that the orthorhombic → cubic phase transition causes the Mn 3 d and O 2 p bands to overlap and mix covalently, transforming α -Mn 2 O 3 from a semiconductor to a semimetal. This subtle change in structure also modifies Mn-O-Mn bond distances, which may improve the activity of the material in oxygen electrochemistry. OER and ORR experiments were performed using the same electrode at various temperatures. They show a jump in the exchange current density near the phase change temperature, demonstrating the higher activity of the cubic phase., Competing Interests: No potential conflict of interest was reported by the authors., (© 2021 The Author(s). Published by National Institute for Materials Science in partnership with Taylor & Francis Group.)

Amorphous bimetallic borides are an emerging class of catalytic nanomaterial that has demonstrated excellent catalytic performance due to its glass-like structure, abundant unsaturated active sites, and synergistic electronic effects. However, the creation of mesoporous Earth-abundant bimetallic metal borides with tunable metal proportion remains a challenge. Herein, we develop a sophisticated and controllable dual-reducing agent strategy to synthesize the mesoporous nickel-cobalt boron (NiCoB) amorphous alloy spheres (AASs) with adjustable compositions by using a soft template-directed assembly approach. The selective use of tetrabutylphosphonium bromide (Bu 4 PBr) is beneficial to generate well-defined mesopores because it both moderates the reduction rate by decreasing the reducibility of M 2+ species and prevents the generation of soap bubbles. Our meso-Ni 10.0 Co 74.5 B 15.5 AASs generate the highest catalytic performance for the hydrolytic dehydrogenation of ammonia borane (AB). Its high performance is attributed to the combination of optimal synergistic effects between Ni, Co, and B as well as the high surface area and the good mass transport efficiency due to the open mesopores. This work describes a systematic approach for the design and synthesis of mesoporous bimetallic borides as efficient catalysts.

We show how photoexcitation of a single plasmonic nanoparticle (NP) in solution can create a whispering-gallery-mode (WGM) droplet resonator. Small nano/microbubbles are initially formed by laser-induced heating that is localized by the plasmon resonance. Fast imaging shows that the bubbles collect and condense around the NP and form a droplet in the interior of the bubble. Droplets containing dye generated lasing modes with wavelengths that depend on the size of the droplet, refractive index of the solvent, and surrounding environment, matching the behavior of a WGM. We demonstrated this phenomenon with two kinds of Au NPs in addition to TiN NPs and observed cavity diameters as small as 4.8 µm with a free spectral range (FSR) of 12 nm. These results indicate that optical pumping of plasmonic NPs in a gain medium can generate lasing modes that are not directly associated with the plasmon cavity but can arise from its photophysical processes. This process may serve as a method to generate plasmonic/photonic optical microcavities in solution on demand at any location in a solvent using free-space coupling in/out of the cavity.

The electrochemical synthesis of mesoporous ruthenium (Ru) films using sacrificial self-assembled block polymer micelles templates, and its electrochemical surface oxidation to RuO x is described. Unlike standard methods such as thermal oxidation, the electrochemical oxidation method described here retains the mesoporous structure. Ru oxide materials serve as high-performance supercapacitor electrodes due to their excellent pseudocapacitive behavior. The mesoporous architectured film shows superior specific capacitance (467 F g -1 Ru ) versus a nonporous Ru/RuO x electrode (28 F g -1 Ru ) that is prepared via the same method but omitting the pore-directing polymer. Ultrahigh surface area materials will play an essential role in increasing the capacitance of this class of energy storage devices because the pseudocapacitive redox reaction occurs on the surface of electrodes., (© 2020 Wiley-VCH GmbH.)

High-surface-area mesoporous materials expose abundant functional sites for improved performance in applications such as gas storage/separation, catalysis, and sensing. Recently, soft templates composed of amphiphilic surfactants and block copolymers have been used to introduce mesoporosity in various materials, including metals, metal oxides and carbonaceous compounds. In particular, mesoporous metals are attractive in electrocatalysis because their porous networks expose numerous unsaturated atoms on high-index facets that are highly active in catalysis. In this protocol, we describe how to create mesoporous metal films composed of gold, palladium, or platinum using block copolymer micelle templates. The amphiphilic block copolymer micelles are the sacrificial templates and generate uniform structures with tunable pore sizes in electrodeposited metal films. The procedure describes the electrodeposition in detail, including parameters such as micelle diameters, deposition potentials, and deposition times to ensure reproducibility. The micelle diameters can be controlled by swelling the micelles with different solvent mixtures or by using block copolymer micelles with different molecular weights. The deposition potentials and deposition times allow further control of the mesoporous structure and its thickness, respectively. Procedures for example applications are included: glucose oxidation, ethanol oxidation and methanol oxidation reactions. The synthetic methods for preparation of mesoporous metal films will take ~4 h; the subsequent electrochemical tests will take ~5 h for glucose sensing and ~3 h for alcohol oxidation reaction.

Mesoporous metal sulfide hybrid (meso-MoS 2 /CoMo 2 S 4 ) materials via a soft-templating approach using diblock copolymer polystyrene- block -poly(acrylic acid) micelles are reported. The formation of the meso-MoS 2 /CoMo 2 S 4 heterostructures is based on the sophisticated coassembly of dithiooxamide and metal precursors ( i.e. , Co 2+ , PMo 12 ), which are subsequently annealed in nitrogen atmosphere to generate the mesoporous material. Decomposing the polymer leaves behind mesopores throughout the spherical MoS 2 /CoMo 2 S 4 hybrid particles, generating numerous electrochemical active sites in a network of pores that enable faster charge transfer and mass/gas diffusion that enhance the electrocatalytic performance of MoS 2 /CoMo 2 S 4 . Doping the spherical meso-MoS 2 /CoMo 2 S 4 heterostructures with iron improves the electronic properties of the hybrid meso-Fe-MoS 2 /CoMo 2 S 4 material and consequently results in its superior electrochemical activities for both hydrogen evolution reaction and oxygen evolution reaction.

Two-dimensional metal-organic frameworks (2D MOFs) are an attractive platform to develop new kinds of catalysts because of their structural tunability and large specific surface area that exposes numerous active sites. In this work, we report a general method to synthesize benzene dicarboxylic acid (BDC)-based MOFs with hierarchical 3D morphologies composed of 2D nanosheets or nanoplates. In our proposed strategy, acetonitrile helps solvate the metal ions in solution and affects the morphology, while polyvinylpyrrolidone (PVP) serves as a shape-control agent to assist in the nucleation and growth of MOF nanosheets. PVP also acts as a depletion agent to drive the assembly of the hierarchical sheet/plate-like M-BDC under solvothermal conditions. Further, we also demonstrate the flexibility of the proposed method using numerous coordinating metal ions (M = Cu, Mn, Ni, and Zr). The potential of these MOFs for electrochemical glucose sensing is examined using the hierarchical sheet-like Ni-BDC MOF as the optimum sample. It drives the electrocatalytic oxidation of glucose over a wide range (0.01 mM to 0.8 mM) with high sensitivity (635.9 μA mM -1 cm -2 ) in the absence of modification with carbon or the use of conductive substrates. It also demonstrates good selectivity with low limit of detection (LoD = 6.68 μM; signal/noise = 3), and fast response time (<5 s)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Selective hydrogenation of nitriles is an industrially relevant synthetic route for the preparation of primary amines. Amorphous metal-boron alloys have a tunable, glass-like structure that generates a high concentration of unsaturated metal surface atoms that serve as active sites in hydrogenation reactions. Here, a method to create nanoparticles composed of mesoporous 3D networks of amorphous nickel-boron (Ni-B) alloy is reported. The hydrogenation of benzyl cyanide to β-phenylethylamine is used as a model reaction to assess catalytic performance. The mesoporous Ni-B alloy spheres have a turnover frequency value of 11.6 h -1 , which outperforms non-porous Ni-B spheres with the same composition. The bottom-up synthesis of mesoporous transition metal-metalloid alloys expands the possible reactions that these metal architectures can perform while simultaneously incorporating more Earth-abundant catalysts., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Plasmonic metal nanostructures support intense nanoscale electromagnetic hotspots that can be modulated in an active plasmonic device. Electrical manipulation is a reversible route to manipulate plasmon resonances in sub-nanoscale distances because a bias voltage can modify the electron tunneling barrier. In this manuscript, we use time-dependent density functional theory (TDDFT) to examine the impact of quantum effects on an asymmetric nanoparticle dimer composed of an aluminum (Al) nanoparticle on a much larger Al rectangular cuboid. This asymmetric system is intended to model some of the effects of a metal nanoparticle coupling to a metal film which is a prototypical plasmonic antenna structure. As the distance between the asymmetric dimer shrinks, the dipolar gap plasmon (DGP) redshifts and a charge transfer plasmon (CTP) appears that is influenced by optically-induced conductance in the nanoscale junction. The relatively high optical conductivity of Al enables a smooth transition from capacitive to conductive coupling, allowing us to find the DGP-CTP crossover distance (d ∼ 6 Å). Surprisingly, a closer evaluation of crossover plasmon resonance revealed two separate peaks with near-field distributions that match the CTP and anti-bonding mode of the gap plasmon. Applying an electrical bias to this crossover system modifies the effective conductance of the tunneling barrier, making it possible to reversibly tune the wavelength of the plasmon modes. This work demonstrates how asymmetry becomes a key feature in active plasmonic devices using electrical bias, because asymmetry enables the use of positive and negative biases to tune the system over a broader range of wavelengths.

Generating high surface area mesoporous transition metal boride is interesting because the incorporation of boron atoms generates lattice distortions that lead to the formation of amorphous metal boride with unique properties in catalysis. Here we report the first synthesis of mesoporous cobalt boron amorphous alloy colloidal particles using a soft template-directed assembly approach. Dual reducing agents are used to precisely control the chemical reduction process of mesoporous cobalt boron nanospheres. The Earth-abundance of cobalt boride combined with the high surface area and mesoporous nanoarchitecture enables solar-energy efficient photothermal conversion of CO 2 into CO compared to non-porous cobalt boron alloys and commercial cobalt catalysts., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Alloying palladium (Pd) catalysts with various metalloid and nonmetal elements can improve their catalytic performance in different chemical reactions. However, current nanosynthesis methods can only generate Pd alloys containing one metalloid or nonmetal, which limits the types of element combinations that may be used to improve Pd-based nanocatalysts. Herein, we report a simple soft-templating synthetic strategy to co-alloy Pd with the metalloid boron (B) and the nonmetal phosphorus (P) to generate ternary PdBP mesoporous nanospheres (MSs) with three-dimensional dendritic frameworks. We use a one-step aqueous synthesis method where dimethylamine borane and sodium hypophosphite serve as the B and P sources, respectively, as well as the co-reducing agents to drive the nucleation and growth of ternary PdBP alloy on a sacrificial dioctadecyldimethylammonium chloride template. The concentration of metalloid to nonmetal and the diameters of dendritic MSs can be tailored. The synthetic protocol is also extended to other multicomponent PdMBP alloy MSs to generate different types of dendritic mesoporous frameworks. Boron and phosphorus are known to accelerate the kinetics of the electrochemical oxygen reduction reaction (ORR) and alcohol oxidation reactions (AORs), because their alloys promote the decomposition of oxygen-containing intermediates on Pd surfaces. The dendritic mesoporous morphology of the ternary PdBP MSs also accelerates electron/mass transfer and exposes numerous active sites, enabling better performance in the ORR and AORs. Extending the surfactant-templating synthetic route to multiple types of elements will enable the generation of libraries of multicomponent metal-metalloid-nonmetal alloy nanostructures with functions that are suitable for various targeted applications.

Mesoporous metals have attracted a lot of interest due to their wide range of applications, particularly in catalysis. We previously reported the preparation of mesoporous Pd using block copolymer micelle templates ( Chem. Sci. 2019 , 10 , 4054). Here we extend this synthetic concept to generate alloyed spherical palladium-copper (PdCu) nanoparticles with an open porous network and uniform morphology. This one-pot synthesis is initiated by water-induced micellization of the block copolymer, followed by the chemical reduction, nucleation, and growth of mesoporous spherical alloy nanoparticles. Porosity enables accessibility to numerous active sites throughout the interior and exterior surfaces of the nanoparticles. Mesoporous nanoparticles composed of Pd and Cu alloy exhibit enhanced electrocatalytic activity and stability in the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR).

Plasmonic metal nanoparticles arranged in periodic arrays can generate surface lattice plasmon resonances (SLRs) with high Q -factors. These collective resonances are interesting because the associated electromagnetic field is delocalized throughout the plane of the array, enabling applications such as biosensing and nanolasing. In most cases such periodic nanostructures are created via top-down nanofabrication processes. Here we describe a capillary-force-assisted particle assembly method (CAPA) to assemble monodisperse single-crystal colloidal Ag cuboctahedra into nearly defect-free >1 cm 2 hexagonal lattices. These arrays are large enough to be measured with conventional ultraviolet-visible spectroscopy, which revealed an extinction peak with a Q -factor of 30 at orthogonal illumination and up to 80 at oblique illumination angles. We explain how the experimental extinction changes with different light polarizations and angles of incidence, and compare the evolution of the peaks with computational models based on the coupled dipole approximation and the finite element method. These arrays can support high Q -factors even when exposed to air, because of the high aspect ratio of the single-crystal nanoparticles. The observation of SLRs in a self-assembled system demonstrates that a high level of long-range positional control can be achieved at the single-particle level.

We experimentally determined the dispersion of the complex third-order nonlinear optical susceptibility χ (3) of Au nanorods over a wide bandwidth (370 - 800 nm). Compared to bulk Au, these nanorods exhibit greatly enhanced nonlinearities that can be manipulated by geometrical parameters. Accurately measuring the χ (3) values of nanostructured metals is challenging because χ (3) is strongly influenced by the local field effects. Hence the current published χ (3) values for Au nanorods have huge variations in both magnitude and sign because Z-scan measurements are used almost exclusively. This work combines pump-probe methods with spectroscopic ellipsometry to show that Au nanorods exhibit strong wavelength dependence and enhanced χ (3) in the vicinity of the longitudinal plasmon mode and explains where the regions of SA and RSA exist and how focusing and defocusing affects χ (3) . In this context, the results highlight the importance of the dispersion of the quantity χ (3) to design plasmonic platforms for nanophotonics applications.

Mesoporous gold (mesoAu) nanospheres support enhanced (electro)catalytic performance owing to their three-dimensional (3D) interior mesochannels that expose abundant active sites and facilitate electron/mass transfers. Although various porous Nanostructured Au has been fabricated by electrochemical reduction, alloying-dealloying and hard/soft templating methods, successful synthesis of mesoAu nanospheres with tailorable sizes and porosities remains a big challenge. Here we describe a novel surfactant-directed synthetic route to fabricate mesoAu nanospheres with 3D interconnected mesochannels by using the amphiphilic surfactant of C 22 H 45 N + (CH 3 ) 2 -C 3 H 6 -SH (Cl - ) (C 22 N-SH) as the mesopore directing agent. C 22 N-SH can not only self-reduce trivalent Au(iii)Cl 4 - to monovalent Au(i), but also form polymeric C 22 N-S-Au(i) intermediates via covalent bonds. These C 22 N-S-Au(i) intermediates facilitate the self-assembly into spherical micelles and inhibit the mobility of Au precursors, enabling the crystallization nucleation and growth of the mesoAu nanospheres via in situ chemical reduction. The synthetic strategy can be further extended to tailor the sizes/porosities and surface optical properties of the mesoAu nanospheres. The mesoAu nanospheres exhibit remarkably enhanced mass/specific activity and improved stability in methanol electrooxidation, demonstrating far better performance than non-porous Au nanoparticles and previously reported Au nanocatalysts. The synthetic route differs markedly from other long-established soft-templating approaches, providing a new avenue to grow metal nanocrystals with desirable nanostructures and functions.

Creating CsPbBr 3 perovskite nanocrystals with bright blue emission is challenging because their optical properties depend sensitively on structure. Growing perovskites in mesoporous templates bypasses some of these purification issues because the size of the nanocrystal is governed by the dimensions of the pores. Mesoporous silica consisting of aligned channels with tunable diameter can be easily synthesized and used as a template. When the perovskite solution evaporates and retreats, some of the liquid remains trapped in the interconnecting pores by discontinuous dewetting. The precursor crystallizes, generating stable ca. 3.1 nm blue-emitting perovskite nanocrystals. The mesoporous template also serves as a protective barrier to preserve the optical properties of the CsPbBr 3 from atmospheric conditions. Compared to the bulk crystals and the powder composite, the strong blue-shift of the emission peak in the film is accompanied by a decrease in the longer lifetime component and an 8-fold increase in the external quantum efficiency., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Efficient collection and safe disposal of toxic metals ions from aqueous solutions is critical for applications in environmental remediation. Although extensive efforts have been devoted to the synthesis of functional TiO 2 materials, photocatalytic reduction (photoreduction) of aqueous metal ions into solid metals remains a challenge. We designed a TiO 2 nanoparticle-decorated layered titanate (K 2 Ti 4 O 9 ) material that retained the cation exchange ability of K 2 Ti 4 O 9 but also possessed the enhanced charge separation efficiency of K 2 Ti 4 O 9 . Combining cation exchange with enhanced charge separation efficiency results in a heterostructured material with remarkably high activity for the photoreduction of metal ions. Initially we demonstrated how the photocatalyst can efficiently reduce aqueous Ni 2+ cations, whereas the benchmark TiO 2 -based P25 catalyst showed little to no activity. The resulting Ni-deposited heterostructure can then be used as a catalyst for visible light-induced photocatalytic H 2 evolution in water.

Mixed metal oxide nanoparticles have interesting physical and chemical properties, but synthesizing them with colloidal methods is still challenging and often results in very heterogeneous structures. Here, we describe a simple method to synthesize mesoporous titania nanoparticles implanted with a uniform distribution of copper oxide nanocrystals (CuO@MTs). By calcining a titanium-based metal-organic framework (MIL-125) in the presence of Cu ions, we can trap the Cu in the TiO 2 matrix. Removal of the organic ligand creates mesoporosity and limits phase separation so that tiny CuO nanocrystals form in the interstices of the TiO 2 . The CuO@MTs exhibits superior performance for photocatalytic hydrogen evolution (4760 μmol h -1 ) that is >90 times larger than pristine titania.