Fabrications of hollow nanocubes of Cu(2)O and Cu via reductive self-assembly of CuO nanocrystals

Contributions of Surface Oxidizing Species and Cu+ to the Antibacterial Activities of Cu2O with Different Crystalline Structures

Although precise regulation of the crystalline structures of metal oxides is an effective method to improve their antibacterial activities, the corresponding mechanisms involved in this process are still unclear. In this study, three kinds of cuprous oxide (Cu2O) samples with different structures of cubes, octahedra, and rhombic dodecahedra (c-Cu2O, o-Cu2O, and r-Cu2O) have been successfully synthesized and their antibacterial activities are compared. The antibacterial activities follow the order of r-Cu2O > o-Cu2O > c-Cu2O, revealing the significant dependence of the antibacterial activities on the crystalline structures of Cu2O. Quenching experiments, as well as the NBT and DPD experiments indicate that ≡CuII─OO• superoxo and ≡CuII─OOH peroxo, instead of •OH, O2•-, and H2O2, are the primary oxidizing species in the oxidative damage to E. coli. Raman analysis further confirms the presence of both ≡CuII─OO• superoxo and ≡CuII─OOH peroxo on the surface of r-Cu2O. On the other hand, the NCP experiment reveals that Cu+, instead of Cu2+, also contributes to the antibacterial process. This study provides new insight into the antibacterial mechanisms of Cu2O.

Synthesis of N-Alkyl Substituted Benzimidazoquinazolinones

Aromatic N-heterocycles, especially benzimidazoquinazolinones featuring alkyl chains, hold significant pharmaceutical relevance. Here, we introduce a streamlined one-pot, 2-fold Cu-catalyzed C-N bond formation protocol for the efficient synthesis of diverse N-alkyl benzimidazoquinazolinone derivatives. This method showcases a broad substrate scope, leveraging readily accessible alkyl halides and delivers the desired cyclized products in excellent yields. Additionally, the methodology enabled the synthesis of an antitumor agent with satisfactory yield, highlighting its utility in medicinal chemistry endeavors.

Controlled Synthesis and Uniform Anchoring of Hollow CuxO Nanocubes on Carbon Nanofiber for Enhanced Se(S)-Se(S) Bond Activation

In the present study, we fabricated hollow cubic Cu_xO nanoparticles (∼23 nm) incorporated with CNF (HC-Cu_xO/CNF) through controlled thermal oxidation of solid cubic Cu₂O nanoparticles (∼21 nm) supported on carbon nanofibers (SC-Cu₂O/CNF) under airflow, exploiting the nanoscale Kirkendall effect. These hollow Cu_xO nanocubes with increased surface areas exhibited outstanding catalytic activity for unsymmetrical chalcogenide synthesis under ligand-free conditions.

Seeking regularity from irregularity: unveiling the synthesis-nanomorphology relationships of heterogeneous nanomaterials using unsupervised machine learning

Nanoscale morphology of functional materials determines their chemical and physical properties. However, despite increasing use of transmission electron microscopy (TEM) to directly image nanomorphology, it remains challenging to quantify the information embedded in TEM data sets, and to use nanomorphology to link synthesis and processing conditions to properties. We develop an automated, descriptor-free analysis workflow for TEM data that utilizes convolutional neural networks and unsupervised learning to quantify and classify nanomorphology, and thereby reveal synthesis-nanomorphology relationships in three different systems. While TEM records nanomorphology readily in two-dimensional (2D) images or three-dimensional (3D) tomograms, we advance the analysis of these images by identifying and applying a universal shape fingerprint function to characterize nanomorphology. After dimensionality reduction through principal component analysis, this function then serves as the input for morphology grouping through unsupervised learning. We demonstrate the wide applicability of our workflow to both 2D and 3D TEM data sets, and to both inorganic and organic nanomaterials, including tetrahedral gold nanoparticles mixed with irregularly shaped impurities, hybrid polymer-patched gold nanoprisms, and polyamide membranes with irregular and heterogeneous 3D crumple structures. In each of these systems, unsupervised nanomorphology grouping identifies both the diversity and the similarity of the nanomaterial across different synthesis conditions, revealing how synthetic parameters guide nanomorphology development. Our work opens possibilities for enhancing synthesis of nanomaterials through artificial intelligence and for understanding and controlling complex nanomorphology, both for 2D systems and in the far less explored case of 3D structures, such as those with embedded voids or hidden interfaces.

Facile synthesis of nanocellulose-based Cu2O/Ag heterostructure as a surface-enhanced Raman scattering substrate for trace dye detection

Semiconductor metal-oxide/metal heterostructures with synergetic properties have potential applications in photocatalysis and optical sensors. Here, Cu₂O sub-micro cubes were synthesized under environmentally benign conditions using 2, 2, 6, 6-tetramethylpyperdine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils as a reducing and stabilizing agent. Then the surface of the Cu₂O cubes was decorated with silver nanoparticles (AgNPs) by a substitution reaction. The Cu₂O/Ag heterostructures within the cellulose nanofibrils (CNFs) network were employed as a promising surface-enhanced Raman scattering (SERS) assay for efficient sensing of methylene blue (MB), reaching a maximum enhancement factor (EF) of 4.0 × 10⁴. Their SERS intensities depended on the coverage density of AgNPs and the wavelength of the excitation laser. The excellent SERS performance may result from the charge transfer between Ag and Cu₂O molecules and the strong electromagnetic field at the interface. The CNF-Cu₂O/Ag substrates were capable of detecting MB dye down to 10^-8 M level with a relative standard deviation of 10-15%, demonstrating great sensitivity and reproducibility.

Engineering Active Sites of Gold-Cuprous Oxide Catalysts for Electrocatalytic Oxygen Reduction Reaction

Understanding how the catalyst morphology influences surface sites is crucial for designing active and stable catalysts and electrocatalysts. We here report a new approach to this understanding by decorating gold (Au) nanoparticles on the surface of cuprous oxides (Cu₂O) with three different shape morphologies (spheres, cubes, and petals). The Au-Cu₂O particles are dispersed onto carbon nanotube (CNT) matrix with high surface area, stability, and conductivity for oxygen reduction reaction. A clear morphology-dependent enhancement of the electrocatalytic activity is revealed. Oxygenated gold species (AuO^-) are found to coexist with Au⁰ on the cube and petal catalysts, whereas only Au⁰ species are present on the sphere catalyst. The AuO^- species function effectively as active sites, resulting in the improved catalytic performance by changing the reaction mechanism. The enhanced catalytic performance of the petal-shaped catalyst in terms of onset potential, half-wave potential, diffusion-limited current density, and stability is closely associated with the presence of the most abundant AuO^- species on its surface. Highly active AuO^- species are identified on the surface of the catalysts as a result of the unique structural characteristics, which is attributed to the structural origin of high activity and stability. This insight constitutes the basis for assessing the detailed correlation between the morphology and the electrocatalytic properties of the nanocomposite catalysts, which has implications for the design of surface-active sites on metal/metal oxide electrocatalysts.

p-Cu2O/n-ZnO heterojunction thin films with enhanced photoelectrochemical properties and photocatalytic activities for norfloxacin

A two-step electrochemical deposition technique was applied to fabricate p-Cu₂O/n-ZnO heterojunction thin films. The influence of the deposition potential upon photoelectric performance of the prepared samples was examined utilizing XRD, XPS, SEM, UV-Vis, and electrochemical tests. The results show that the deposition potential has a substantial influence on the properties of the prepared samples. When the deposition potential is -0.45 V, the peak intensity of the (111) crystal plane of the prepared heterojunction is the highest, the band gap increased, and the morphology changes obviously compared to those of Cu₂O. The transient photocurrent value is three times that of pure Cu₂O, and the charge transfer resistance significantly reduced. The p-Cu₂O/n-ZnO heterojunction has a high carrier concentration. Photocatalytic degradation experiments show that degradation rate of norfloxacin increases by 14.4%-76.6%. The enhanced photocatalytic performance of Cu₂O is mainly due to the formation of a high-quality heterojunction and the change in the energy band structure, which promotes the transfer rate of the carrier and the separation of photogenic electron hole pairs, thus effectively improving the catalytic efficiency of photocatalysts. Active species detection experiments reveal that positive hole and superoxide anion radical play leading roles in norfloxacin molecule decomposition. In addition, a possible mechanism for the photocatalytic performance of p-Cu₂O enhanced by n-ZnO is proposed according to the analysis of the bandgap of p-Cu₂O and n-ZnO, along with the built-in electric field formed in the p-n heterojunction. This study provides an effective and alternative method for removing norfloxacin residues in wastewater.

Electron cloud migration effect-induced lithiophobicity/lithiophilicity transformation for dendrite-free lithium metal anodes

Enabling stable lithium metal anodes is significant for developing electrochemical energy storage systems with higher energy density. However, safety hazards, infinite volume expansion, and low coulombic efficiency (CE) of lithium metal anodes always hinder their practical application. Herein, a nano-thickness lithiophilic Cu-Ni bimetallic coating was synthesized to prepare dendrite-free lithium metal anodes. The electron cloud migration effect caused by the different electronegativities of Cu and Ni can achieve lithiophobicity/lithiophilicity transformation and thus promote uniform Li deposition/dissolution. By changing the ratio of Cu to Ni, the electron cloud migration can be reasonably adjusted for obtaining dendrite-free lithium anodes. As a result, the as-obtained Cu-Ni bimetallic coating is able to guarantee dendrite-free lithium metal anodes with a stable long cycling time (>1500 hours) and a small voltage hysteresis (∼26 mV). In addition, full cells with LiFePO₄ as a cathode present excellent cycling stability and high coulombic efficiency. This work can open a new avenue for optimizing the lithiophilicity of materials and realizing dendrite-free anodes.

Remarkable SERS Detection by Hybrid Cu2O/Ag Nanospheres

Cu₂O nanospheres (NSs) were synthesized by modifying the glucose reduction method. Based on this method, Cu₂O/Au (Ag) NSs were further prepared by in situ reduction of HAuCl₄ (via electron beam evaporation of Ag). With Rhodamine 6G (R6G) as probe, the surface-enhanced Raman scattering (SERS) characteristics of the three samples were systematically studied. The experiment results showed that the enhancement factor (EF) of Cu₂O/Au (Ag) NSs as 1.25 × 10⁸ (2.74 × 10⁹) and the ultralow detection limit (LOD) as 8.07 × 10^-12 (1.13 × 10^-13) M for R6G. The excellent performance of SERS may be due to the charge transfer (CT) between metal-semiconductor (MS) molecules and the strong electromagnetic field (E-field) of each hot spot. In addition, discrete dipole approximation (DDA) simulations were performed to simulate the E-field enhancement of the Cu₂O and Cu₂O/Au (Ag) NSs in a three-dimensional (3D) configuration. These further supported that the high SERS performance for R6G is because of the powerful E-field coupling between neighboring Au (Ag) NPs and the surface plasmon resonance (SPR) effect. The Cu₂O/Ag NSs have potential in applications such as biomedicine, food safety, and environmental monitoring because of their high sensitivity and good reproducibility.

Fabrication of Few-Layer Graphene-Supported Copper Catalysts Using a Lithium-Promoted Thermal Exfoliation Method for Methanol Oxidative Carbonylation

Exfoliation of graphene oxide (GO) via thermal expansion is regarded as the most promising approach to obtain few-layer graphene (FLG) in bulk. Herein, we introduce an efficient strategy for improving the exfoliation process by adding a tiny amount of lithium nitrate in the precursors, which significantly enhances the removal of oxygen-containing functional groups and produces 1-2 layer graphene. FLG-supported highly dispersed Cu nanoparticles (NPs, ≈4.2 nm) can be further synthesized through exfoliating the mixture of GO, lithium nitrate, and copper(II) nitrate, which displayed superior catalytic activity and stability in the synthesis of dimethyl carbonate (DMC) using liquid methanol oxidative carbonylation. The characterization results demonstrate that during the thermal expansion process, lithium nitrate was decomposed to Li₂O and immediately reacted with CO₂ released by the decomposition of GO to form stable Li₂CO₃, which promotes efficient charge transfer and produces Cu^δ+ (0 < δ < 1) species in the Cu/Li-PGO catalyst. Density functional theory calculations prove that the presence of Cu^δ+ markedly facilitates CO adsorption over the resulting catalyst and causes a decrease of the energy barrier of the rate-limiting step for DMC formation (CO insertion). These findings give a theoretical explanation of the enhanced catalytic performance of the Cu/Li-PGO catalyst. The present work provides a simple and practical avenue to the exfoliation of graphene and the dispersions of metal NPs on graphene sheets.

Synthesis of Mesoporous Copper Aluminosilicate Hollow Spheres for Oxidation Reactions

Hollow functional metal silicate materials have received the most interest due to their large inner space, permeable and functional shell, lighter density, and better use of material compared to their solid counterparts. While tremendous success has been made in the synthesis of individual metal silicates with uniform morphology, the synthesis of multiphase hollow silicates has not been explored yet, although their direct applications could be promising. In this study, mesoporous aluminosilicate spheres (MASS) are transformed to submicrometer copper aluminosilicate hollow spheres (CASHS) via a one-pot hydrothermal process. CASHS has a hollow interior with Cu-Al-Si thorn-like moieties in a lamellar structure on its outer shell. The structure and morphology of CASHS are unique and different from the previously reported tubular copper silicates that are emanated from Stöber silica spheres. Herein, we also demonstrate that the extent of hollowing in CASHS can be attained by controlling the aluminum content of pristine MASS, highlighting the existence of parameters for in situ controlling the shell thickness of hollow materials. The application of CASHS as a potential heterogeneous catalyst has been directed to important oxidation processes such as olefin oxidation and the advanced oxidation process (AOP). In cyclohexene oxidation, for instance, high selectivity to cyclohex-2-en-1-one is achieved under moderate conditions using tert-butyl hydroperoxide as the oxidant. CASHS is a robust heterogeneous catalyst and recyclable for this reaction. CASHS-derived catalysts also favor AOP and enhance the removal of cationic dyes together with H₂O₂ through an adsorption-degradation process.

Top-Open Hollow Nanocubes of Ni-Doped Cu Oxides on Ni Foam: Scalable Oxygen Evolution Electrode via Galvanic Displacement and Face-Selective Etching

Self-standing and cost-effective electrodes for high-performance oxygen evolution reaction (OER) are vital for emerging energy storage and conversion technologies. We report a scalable binder-free OER electrode with open hollow nanocubes of Ni-doped CuOx on Ni foam (hNC/NF) through spontaneous galvanic displacement followed by simple electrochemical oxidation. Face-selective etching for the unique structure of hollow nanocubes with large open ends is achieved by utilizing the different accessibility of the top and side faces of cubes to solution species, more specifically the depletion of reactants between the densely supported nanocubes. Besides, the in situ deposition on Ni foam allows spontaneous Ni doping, which, as revealed by DFT calculations, fortunately strengthens the adsorption of oxygenated intermediates and therefore could optimize the free energy path of OER on Cu oxides. Benefiting further from the high accessible surface area of the unique open hollow architecture, the hNC/NF exhibits an outstanding OER activity with a small overpotential (η = 305 mV at 10 mA cm^-2) as well as excellent stability without significant decay after 120 h operation. To our knowledge, this should represent the best OER performance of Cu-based electrocatalysts and is competitive with those based on Fe-group metals. Besides, the hNC/NF-based water electrolyzer delivers a performance of 1.50 V cell voltage at 10 mA cm^-2, offering great promise for practical application.

Copper-catalyzed cascade C–N coupling/C–H amination: one pot synthesis of imidazo[1,2-b]indazole

A one-pot, two-fold C–N bond formation protocol has been developed for the construction of imidazo[1,2-b]indazole derivatives.

Gold incorporated hematite nanocatalyst for solvent-free CO2 fixation under atmospheric pressure

Au/α-Fe₂O₃ as a nanocatalyst for the conversion of epoxides to cyclic carbonates utilizing CO₂ under 1 atm. pressure.

Architecture and Preparation of Hollow Catalytic Devices

Since pioneering work done in the late 1990s, synthesis of functional hollow materials has experienced a rapid growth over the past two decades while their applications have been proven to be advantageous across many technological fields. In the field of heterogeneous catalysis, the development of micro- and nanoscale hollow materials as catalytic devices has also yielded promising results, because of their higher activity, stability, and selectivity. Herein, the architecture and preparation of these catalysts with tailorable composition and morphology are reviewed. First, synthesis of hollow materials is introduced according to the classification of template mediated, template free, and combined approaches. Second, different architectural designs of hollow catalytic devices, such as those without functionalization, with active components supported onto hollow materials, with active components incorporated within porous shells, and with active components confined within interior cavities, are evaluated respectively. The observed catalytic performances of this new class of catalysts are correlated to structural merits of individual configuration. Examples that demonstrate synthetic approaches and architected configurations are provided. Lastly, possible future directions are proposed to advance this type of hollow catalytic devices on the basis of our personal perspectives.

Water-guided synthesis of well-defined inorganic micro-/nanostructures

Water is one of the most commonplace solvents employed in wet chemical synthesis; however, it can sometimes play important roles such as an effective inducer or morphology-directing agent when introduced into a special reaction system, resulting in the formation of inorganic micro-/nanostructures with well-defined configurations. A better understanding of the key roles of water in the chemical synthesis will unlock a door to the design of many more novel single-component and hybrid nanocomposite architectures. Therefore, it is imperative to comprehensively review the topic of water-guided synthesis of well-defined micro-/nanostructures. Unfortunately, the significance of water has been underestimated and an in-depth study about the exact action of water in morphology-control is still lacking. In this review, we focus on the recent advances made in the development of the shape-controlled synthesis of inorganic micro-/nanostructures achieved by only adjusting the amount of water through some typical examples, including noble metals, metal oxides, perovskites, metal sulfides and oxysalts. In particular, the theory principles, synthesis strategies and growth mechanisms of the water-guided synthesis of well-defined inorganic micro-/nanostructures have been mainly highlighted. Finally, several current issues and challenges of this topic that need to be addressed in future investigations are briefly presented.

Construction of rGO wrapping Cu2O/ZnO heterostructure photocatalyst for PNP and PAM degradation

Copper and zinc composite oxides (Cu₂O/ZnO) were synthesized by an impregnation-reduction-air oxidation method. A series of Cu₂O/ZnO/rGO ternary composites were prepared by coupling with graphene oxide (GO) with different mass fractions in a solvothermal reaction system. The microscopic morphology, crystal structure, and optical characteristics of the photocatalysts were characterized. The degradation of p-Nitrophenol (PNP) and polyacrylamide (PAM) by photocatalytic materials under simulated solar irradiation were studied, and the degradation kinetics were also investigated. The results showed that cubic Cu₂O was modified by ZnO nanorods and distributed on rGO nanosheets. The ternary Cu₂O/ZnO/rGO nanocomposites have stronger simulated solar absorption ability and higher photodegradation efficiency than pure ZnO and binary Cu₂O/ZnO nanocomposites. When the amount of Cu₂O/ZnO/rGO-10 was 0.3 g L^-1, the degradation rate of 10 mg L^-1 PNP reached 98% at 90 min and 99.6% of 100 mg L^-1 PAM at 30 min. The photocatalytic degradation processes of PNP and PAM all followed the pseudo-first-order kinetic model. Free radical trapping experiments showed that superoxide radicals were the main active substances to improve photocatalytic efficiency. In addition, after four recycles, the catalytic efficiency of Cu₂O/ZnO/rGO-10 was still over 90%. It showed that Cu₂O/ZnO/rGO-10 was a promising catalyst for wastewater treatment because of its good photostability and reusability.

Antibacterial Copper-Hydroxyapatite Composite Coatings via Electrochemical Synthesis

Antibacterial copper-hydroxyapatite (Cu-HA) composite coatings on titanium were synthesized using a novel process consisting of two consecutive electrochemical reactions. In the first stage, HA nanocrystals were grown on titanium using the cathodic electrolytic synthesis. The HA-coated titanium was then used as the cathode in a second reaction stage to electrochemically reduce Cu²⁺ ions in solution to metallic Cu nanoparticles. Reaction conditions were found that result in nanoscale Cu particles growing on the surface of the HA crystals. The two-stage synthesis allows facile control of copper content in the HA coatings. Antibacterial activity was measured by culturing Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) in the presence of coatings having varying copper contents. The coatings displayed copper concentration-dependent antibacterial activity against both types of bacteria, likely due to the slow release of copper ions from the coatings. The observation of antibacterial activity from a relatively low loading of copper on the bioactive HA support suggests that multifunctional implant coatings can be developed to supplement or supplant prophylactic antibiotics used in implant surgery that are responsible for creating resistant bacteria strains.

Unraveling the Morphology-Function Relationships of Polyamide Membranes Using Quantitative Electron Tomography

An understanding of how complex nanoscale morphologies emerge from synthesis would offer powerful strategies to construct soft materials with designed structures and functions. However, these kinds of morphologies have proven difficult to characterize, and therefore manipulate, because they are three-dimensional (3D), nanoscopic, and often highly irregular. Here, we studied polyamide (PA) membranes used in wastewater reclamation as a prime example of this challenge. Using electron tomography and quantitative morphometry, we reconstructed the nanoscale morphology of 3D crumples and voids in PA membranes for the first time. Various parameters governing film transport properties, such as surface-to-volume ratio and mass-per-area, were measured directly from the reconstructed membrane structure. In addition, we extracted information inaccessible by other means. For example, 3D reconstruction shows that membrane nanostructures are formed from PA layers 15-20 nm thick folding into 3D crumples which envelope up to 30% void by volume. Mapping local curvature and thickness in 3D quantitatively groups these crumples into three classes, "domes", "dimples", and "clusters", each being a distinct type of microenvironment. Elemental mapping of metal ion adsorption across the film demonstrates that these previously missed parameters are relevant to membrane performance. This imaging-morphometry platform can be applicable to other nanoscale soft materials and potentially suggests engineering strategies based directly on synthesis-morphology-function relationships.

Mechanism and kinetics of catalytic ozonation for elimination of organic compounds with spinel-type CuAl2O4 and its precursor

CuAl₂O₄ based mixed oxides were used as heterogeneous catalysts for ozone activation to degrade organics in aqueous solution. The solids were thoroughly characterized by SEM/EDS, N₂ physisorption, XRD, FTIR, Pyridine-FTIR, TEM and XPS. We demonstrated that the solid precursor calcined at 300 °C exhibited the best catalytic ozonation activity with respect to CuAl₂O₄ spinel phase obtained at higher temperatures. Such performance was attributed to the better textural properties and a higher density of active sites (hydroxyl groups and Lewis acidity). Specifically, the mixed oxide/O₃ process allows to reach a near complete color removal of the dye solution (100 mg L^-1) in 25 min at neutral pH. Corresponding reaction rate value was measured at 0.112 min^-1 and was clearly higher compared with the single oxide ozonation process (0.071 min^-1 for CuO/O₃ and 0.074 min^-1 for Al₂O₃/O₃). Then, we proposed that such catalytic performance was related to a synergistic function between ≡Cu²⁺ and ≡Al³⁺, which took part of a mechanism of radical formation. In such mechanism, present ≡Al³⁺ could act as a reservoir for surface active sites such as hydroxyl groups and Lewis acid sites, while ≡Cu²⁺ could provide the possibility of electron transfer with ozone for the enhancement of radical generation. We suggested that the interaction between chemisorbed ozone and surface hydroxyl groups initially stabilized on ≡Al³⁺ initiated the generation of reactive radical species. This interaction led as well to the formation of surface adsorbed HO and few O₂^- on ≡Cu²⁺ Lewis acid sites. Besides, the interfacial redox reaction with ozone is favored by the presence of ≡Cu²⁺ following the sequence of ≡Cu²⁺/≡Cu⁺/≡Cu²⁺ redox cycle.

Synthesis of Cu₂O/CuO Nanocrystals and Their Application to H₂S Sensing

Semiconducting metal oxide nanocrystals are an important class of materials that have versatile applications because of their useful properties and high stability. Here, we developed a simple route to synthesize nanocrystals (NCs) of copper oxides such as Cu₂O and CuO using a hot-soap method, and applied them to H₂S sensing. Cu₂O NCs were synthesized by simply heating a copper precursor in oleylamine in the presence of diol at 160 °C under an Ar flow. X-ray diffractometry (XRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) results indicated the formation of monodispersed Cu₂O NCs having approximately 5 nm in crystallite size and 12 nm in colloidal size. The conversion of the Cu₂O NCs to CuO NCs was undertaken by straightforward air oxidation at room temperature, as confirmed by XRD and UV-vis analyses. A thin film Cu₂O NC sensor fabricated by spin coating showed responses to H₂S in dilute concentrations (1–8 ppm) at 50–150 °C, but the stability was poor because of the formation of metallic Cu₂S in a H₂S atmosphere. We found that Pd loading improved the stability of the sensor response. The Pd-loaded Cu₂O NC sensor exhibited reproducible responses to H₂S at 200 °C. Based on the gas sensing mechanism, it is suggested that Pd loading facilitates the reaction of adsorbed oxygen with H₂S and suppresses the irreversible formation of Cu₂S.

Activated carbon aerogel supported copper catalysts for the hydrogenation of methyl acetate to ethanol: effect of KOH activation

Methyl acetate (MA) hydrogenation is crucial for indirect ethanol synthesis through syngas (CO + H₂).

Shape-Controlled Synthesis of Luminescent Hemoglobin Capped Hollow Porous Platinum Nanoclusters and their Application to Catalytic Oxygen Reduction and Cancer Imaging

Engineering hollow and porous platinum nanostructures using biomolecular templates is currently a significant focus for the enhancement of their facet-dependent optical, electronic, and electrocatalytic properties. However, remains a formidable challenge due to lack of appropriate biomolecules to have a structure-function relationship with nanocrystal facet development. Herein, human hemoglobin found to have facet-binding abilities that can control the morphology and optical properties of the platinum nanoclusters (Pt NCs) by regulation of the growth kinetics in alkaline media. Observations revealed the growth of unusual polyhedra by shape-directed nanocluster attachment along a certain orientation accompanied by Ostwald ripening and, in turn, yield well-dispersed hollow single-crystal nanotetrahedrons, which can easily self-aggregated and crystallized into porous and polycrystalline microspheres. The spontaneous, biobased organization of Pt NCs allow the intrinsic aggregation-induced emission (AIE) features in terms of the platinophilic interactions between Pt(II)-Hb complexes on the Pt(0) cores, thereby controlling the degree of aggregation and the luminescent intensity of Pt(0)@Pt(II)−Hb core−shell NCs. The Hb-Pt NCs exhibited high-performance electrocatalytic oxygen reduction providing a fundamental basis for outstanding catalytic enhancement of Hb-Pt catalysts based on morphology dependent and active site concentration for the four-electron reduction of oxygen. The as-prepared Hb-Pt NCs also exhibited high potential to use in cellular labeling and imaging thanks to the excellent photostability, chemical stability, and low cytotoxicity.

Under Diffusion Control: from Structuring Matter to Directional Motion

Self-organization in synthetic chemical systems is quickly developing into a powerful strategy for designing new functional materials. As self-organization requires the system to exist far from thermodynamic equilibrium, chemists have begun to go beyond the classical equilibrium self-assembly that is often applied in bottom-up supramolecular synthesis, and to learn about the surprising and unpredicted emergent properties of chemical systems that are characterized by a higher level of complexity and extended reactivity networks. The present review focuses on self-organization in reaction-diffusion systems. Selected examples show how the emergence of complex morphogenesis is feasible in synthetic systems leading to hierarchically and nanostructured matter. Starting from well-investigated oscillating reactions, recent developments extend diffusion-limited reactivity to supramolecular systems. The concept of dynamic instability is introduced and illustrated as an additional tool for the design of smart materials and actuators, with emphasis on the realization of motion even at the macroscopic scale. The formation of spatio-temporal patterns along diffusive chemical gradients is exploited as the main channel to realize symmetry breaking and therefore anisotropic and directional mechanical transformations. Finally, the interaction between external perturbations and chemical gradients is explored to give mechanistic insights in the design of materials responsive to external stimuli.

Atomic layer deposition of Cu(i) oxide films using Cu(ii) bis(dimethylamino-2-propoxide) and water

To grow films of Cu₂O, bis-(dimethylamino-2-propoxide)Cu(ii), or Cu(dmap), is used as an atomic layer deposition precursor using only water vapor as a co-reactant. Between 110 and 175 °C, a growth rate of 0.12 ± 0.02 Å per cycle was measured using an in situ quartz crystal microbalance (QCM). X-ray photoelectron spectroscopy (XPS) confirms the growth of metal-oxide films featuring Cu(i).

Helical carbon tubes derived from epitaxial Cu-MOF coating on textile for enhanced supercapacitor performance

A new helical carbon tube material has been prepared from epitaxial Cu-MOF coating on textile by calcination treatment.

Cu-enhanced photoelectronic and ethanol sensing properties of Cu2O/Cu nanocrystals prepared by one-step controllable synthesis

Cu₂O/Cu hetero-nanostructures with obviously improved photoelectric and ethanol sensing properties compared to Cu₂O are obtained by a one-step solution method.

Work function: a determining factor of the photodegradation rate of methyl orange via hollow octadecahedron Cu2O crystals

Herein, the work function serves as a crucial factor for controlling the photodegradation efficiency of methyl orange via hollow octadecahedron Cu₂O crystals.

Topological Transformations of Core-Shell Precursors to Hierarchically Hollow Assemblages of Copper Silicate Nanotubes

Functional hollow materials have attracted extensive research attention due to their promising prospects for catalysis. Herein, we report an alternative synthesis of hierarchically hollow structured materials directly from core-shell structured templates, based on confined chemical reactions between the solid matter of a core and shell under hydrothermal conditions. More specifically, we have developed a novel and facile strategy to transform core-shell structured Cu₂O@mSiO₂ (m = mesoporous) to tubular copper silicate assemblages (TCSA). Depending on the original shapes of Cu₂O, TCSA can be tailored as spherical or cubic assemblages with stacking copper silicate nanotubes (inner diameter: 4.5 nm, thickness: 0.8 nm, length: ca. 96 nm) in the shell. Moreover, by utilizing the residual reductive Cu(I) (ca. 10 at% of total surface copper) on TCSA support, in situ generations of Pd nanoparticles (∼4.5 nm) and Au nanoparticles (∼5.8 nm) were successfully achieved based on the spontaneous galvanic replacement reactions. Two integrated nanocatalysts (viz., Pd/TCSA and Au/TCSA) have been prepared with this approach. As an example, Pd/TCSA exhibits excellent activity and recyclability for Suzuki-Miyaura cross-coupling reactions.