The photomediated transformation of silver nanoparticles is both synthetically useful and mechanistically intriguing. Temperature effects on photochemical synthesis of silver nanoparticles are investigated. The morphology of final products is strongly dependent on the reaction temperature: nanodecahedra are formed at a low temperature of 20 °C; nanoprisms are formed at a higher temperature of 40 °C; and a mixture of shapes results at 30 °C. An interesting transformation process is observed at a lower temperature of 20 °C: silver nanoprisms are grown first and then transformed into nanodecahedra completely. We propose that silver seeds in a type of multitwinning are more stable than the platelike structure at lower temperature during the photochemical growth process. The transformed silver nanodecahedra exhibit greatly superior enhancement of Raman scattering compared to silver nanoprisms. These findings may provide a new insight on photomediated synthesis of silver nanostructures and suggest a new way of thinking about control over the morphology of nanoparticles.

A plasmonic bimetallic nanostructure has attracted considerable attention as a promising catalyst for light-driven catalytic reactions. The stability and recovery of the catalysts are still key issues for sustainable development of green chemistry. In this work, we designed and implemented an Au/Pd heterojunction@mesoporous SiO2 yolk–shell nanostructure (Au/Pd@m-SiO2 yolk–shell NPs) for plasmon-enhanced photocatalysis. The heterojunction of Au/Pd enhances the separation of hot electrons and holes under visible light irradiation, and the mesoporous SiO2 shell protects the active Au/Pd NPs from aggregation. The Au/Pd@m-SiO2 yolk–shell NPs exhibit extremely high stability for the plasmon-enhanced catalytic reduction of p-nitrophenol (4-NP) under visible light irradiation. The merging of a plasmonic material and a yolk–shell nanostructure proposes a new way for designing catalysts with good stability and promising activity.

In recent years, shape control has received the most attention in the exploration of Pd nanocrystals (NCs). However, exploring an efficient approach for the systematic production of Pd NCs under similar reaction conditions still presents a significant challenge, which is significantly important to clearly explain the effectiveness of morphology on the catalytic activity of Pd NCs. We designed and accomplished a facile strategy for the morphology transformation between Pd nanosheets and Pd nanotetrahedra by simply controlling the reaction temperature. A growth mechanism was proposed based on TEM images of the time-dependent morphology evolution. The Pd nanosheets and Pd nanotetrahedra exhibit higher activity for the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) compared with the benchmark Pd/C catalysts, and their activities are dependent on the morphology. In particular, Pd nanosheets show an increased activity by 3.81 (MOR) and 2.86 (ORR) times due to their large specific surface area and exposed facets.Download high-res image (210KB)Download full-size image

•Monodisperse and size-controlled Co-N-C electrocatalyst is developed.•The electrocatalyst shows high-density and evenly distributed Co-N active sites.•The electrocatalyst shows higher ORR catalytic performance than commercial Pt/C.•The catalytic mechanisms are systemically investigated.•The assembled cell shows the highest power density among current studies.Heat-treated metal-nitrogen-carbon (M-N-C) materials are emerging as promising non-precious catalysts to replace expensive Pt-based materials for oxygen reduction reaction (ORR) in energy conversion and storage devices. Despite recent progress, their activity and durability are still far from satisfactory. The activity site and particle size are among the most important factors for the ORR activity of M-N-C catalysts. Extensive efforts have been made to reveal the correlation of active site and activity. However, it remains unclear to what extent the particle size will influence the ORR activity of M-N-C materials. Moreover, to the best of our knowledge, controllable synthesis of M-N-C catalysts with high-density activity sites remains elusive. Herein, we develop a straightforward method to produce a monodisperse and size-controlled Co-N-C (Nano-P-ZIF-67) electrocatalyst, and systemically investigate its catalytic mechanisms. Only by optimizing the particle size, Nano-P-ZIF-67 outperforms the commercial 20 wt% Pt/C regarding all evaluating indicators for ORR catalysts in alkaline media including higher catalytic activity, durability, and stronger methanol tolerance. Nano-P-ZIF-67 is assembled into a cell, and the cell shows a power density of 45.5 mW/cm2, which is the highest value among currently studied cathode catalysts. We expect Nano-P-ZIF-67 to be a highly interesting candidate for the next generation of ORR catalysts.Download high-res image (281KB)Download full-size image

Theranostic nanomedicine has shown tremendous promise for more effective and predictive cancer treatment by real-time mornitoring of the delivery of therapeutics to tumors and subsequent therapeutic response. However, the preparation of the theranostic nanoplatforms generally involves complicated procedures to encapsulate the therapeutic and imaging agents into a single nanoformulation. In this work, we develop an innovative nanotheranostic composed of ultrasmall PEG–Bi2S3 nanodots for simultaneous X-ray CT imaging and photothermal therapy. These nanodots possess several unique features: (i) efficient conversion of the NIR light into heat upon laser irradiation; (ii) long circulation time in vivo for effective tumor accumulation; (iii) 100% tumor elimination upon NIR laser irradiation in a tumor xenograft mouse model following systemic injection without obvious side effects; (iv) small size for efficient clearance from the body; and (v) high-performance CT imaging in vivo for potential imaging-guided therapy and the selection of cancer patients with high tumor accumulation. These results strongly suggest that this theranostic nanomedicine may become an effective tool for CT imaging-guided therapy for personalized cancer treatment.

•The photocorrosion of CdS is inhibited by constructing a CdS/NixSy@NF p-n junction to transfer excess holes.•A one-step method is developed for synthesizing the CdS/NixSy@NF heterostructure photoanode.•The CdS/NixSy@NF exhibits high photocurrent and superior stability for photoelectrochemical (PEC) water splitting.Photoelectrochemical (PEC) water splitting holds promise for both sustainable energy generation and energy storage. CdS, a sulphide semiconductor possessing a narrow band gap (2.4 eV) and high photocatalytic activity, has been widely used to build photoanodes for PEC water splitting; however, it also suffers from photocorrosion under irradiation. An innovative method is presented here to significantly improve the stability of CdS photoanodes by constructing a p-n junction comprising CdS/NixSy on nickel foam (NF) via a one-pot hydrothermal method. The n-type CdS is surrounded by p-type NixSy serving as a fast and effective hole receiver of excess holes from CdS. More importantly, the CdS/NixSy shows significantly improved PEC stability compared to the pure CdS electrode, with ≈70% of the initial photocurrent retained after 2000 s of irradiation (>420 nm). This work provides a new insight into the fabrication of other p-n junction self-assembled photoanodes to simultaneously enhance charge separation and transport for efficient and stable solar fuel production.

Here, we designed and implemented a facile strategy for controlling the surface evolution of Pd@Pt core–shell nanostructures by simply adjusting the volume of OH− to control the reducing ability of ascorbic acid and finally manipulating the supersaturation in the reaction system. The surface structure of the obtained Pd@Pt bimetallic nanocrystals transformed from a Pt {111} facet-exposed island shell to a conformal Pt {100} facet-exposed shell by increasing the pH value. The as-prepared well aligned Pd@Pt core–island shell nanocubes present both significantly enhanced electrocatalytic activity and favorable long-term stability toward the oxygen reduction reaction in alkaline media.

Outstanding hydrogen evolution reaction (HER) activity and stability are highly desired for transition metal dichalcogenide (TMD)-based catalysts as Pt substitutes. Here, we theoretically calculated and experimentally showed that adsorbing Pd atoms on the basal plane of defect-rich (DR) MoS2 will effectively modulate the surface electronic state of MoS2 while retaining its active sites, which greatly enhanced the HER activity. Three decoration strategies were used to implement this design: direct epitaxial growth, assembling spherical nanoparticles and assembling Pd nanodisks (NDs). The results showed that only Pd NDs are able to be site-specifically decorated on the basal plane of DR-MoS2 through lamellar-counterpart-induced van der Waals pre-combination and covalent bonding. This Pd ND/DR-MoS2 heterostructure exhibits exceptional Pt-similar HER properties with a low onset-overpotential (40 mV), small Tafel slope (41 mV dec−1), extremely high exchange current density (426.58 μA cm−2) and robust HER durability. These results demonstrate a novel modification strategy by a lamellar metallic nanostructure for designing excellent layered TMD-based HER catalysts.

The catalytic electro-oxidation of ethanol is the essential technique for direct alcohol fuel cells (DAFCs) in the area of alternative energy for the ability of converting the chemical energy of alcohol into the electric energy directly. Developing highly efficient and stable electrode materials with antipoisoning ability for ethanol electro-oxidation remains a challenge. A highly ordered periodic Au-nanoparticle (NP)-decorated bilayer TiO2 nanotube (BTNT) heteronanostructure was fabricated by a two-step anodic oxidation of Ti foil and the subsequent photoreduction of HAuCl4. The plasmon-induced charge separation on the heterointerface of Au/TiO2 electrode enhances the electrocatalytic activity and stability for the ethanol oxidation under visible light irradiation. The highly ordered periodic heterostructure on the electrode surface enhanced the light harvesting and led to the greater performance of ethanol electro-oxidation under irradiation compared with the ordinary Au NPs-decorated monolayer TiO2 nanotube (MTNT). This novel Au/TiO2 electrode also performed a self-cleaning property under visible light attributed to the enhanced electro-oxidation of the adsorbed intermediates. This light-driven enhancement of the electrochemical performances provides a development strategy for the design and construction of DAFCs.Keywords: charge separation; ethanol electro-oxidation; heterostructure; periodic structure; surface plasmon

•An original study on the synthesis of a Pd-Au bimetallic heterostructure.•Bimetallic nanostructure controls the catalytic performance and SPR property.•Plasmonic modulation of the electrocatalytic activity for ethanol oxidation.•SPR induced the hot electrons transfer into the Pd nanopetals from the Au core.Plasmonic modulation of the catalytic performances of metallic nanostructures shows great potential in the development of novel materials for catalysis. In addition to the challenges of devising new catalysts with high activity while maintaining controllable plasmonic properties, the mechanisms underlying the enhancement of the activity by surface plasmon resonance (SPR) are still under exploration. Here, we design a Pd-Au bimetallic hetero structure and use the well-defined SPR property of the core Au NPs to tune its surface electro catalytic activity. The hot electrons are transferred into the Pd nanopetals from the Au core with visible-light irradiation, resulting in an enhancement of the electrocatalytic oxidation of ethanol on Au concurrent with an inhibition on Pd. The anti-poisoning and stability of the as-prepared heterostructures is also enhanced by visible-light irradiation.

•The ZnO-NRs/Au substrate is a promising candidate for developing mass-manufactured, low cost, sensitive, and high-throughput protein microarray platforms.•The large surface area of the ZnO-NRs nanoarrays and the plasmonic coupling effects of the Au nanofilm result in a significant fluorescence signal enhancement.•The cancer biomarker CEA is detected in a broad dynamic range of 100 pg mL−1 to 100 μg mL−1 with a limit of detection of 27 pg mL−1.Microarrays require high sensitivity and a broad dynamic range for high-throughput diagnostics and proteomic analysis. We present the fabrication of novel plasmonic protein microarrays using nanostructured ZnO-Nanorods (ZnO-NRs) on 50 nm Au film that exhibits an enhancement of fluorescence up to 200-fold. The as-prepared plasmonic protein microarrays were used for the detection of the carcinoembryonic antigen (CEA) cancer biomarker. The plasmonic enhancement resulted in a detection limit of 27 pg mL−1 in 0.01 M PBS and a dynamic range of 100 pg mL−1 to 100 μg mL−1. The ZnO-NRs/Au substrates can be mass-manufactured, which is highly promising for the development of low cost, sensitive, and high-throughput protein assay platform for applications in clinical diagnosis.

Porous Pd nanotubes were in situ fabricated on a glass-carbon electrode (GCE) via a one-step galvanic replacement reaction by using cheap, flexible, and ultralong copper nanowires as the sacrificial template. The electrode exhibits excellent electrocatalytic performance for non-enzymatic glucose biosensors, thanks to massive pores and high specific surface area. This non-enzymatic glucose biosensor shows a wide linear response range from 5 μM to 10 mM, with a sensitivity of 6.58 μA mM−1 cm−2, and a detection limit of 1 μM (signal-to-noise ratio of 3).

Photomediated synthesis is a reliable, high yield method for the production of a variety of morphologies of silver nanoparticles. Here, we report synthesis of silver nanoprisms and nanodecahedra with tunable sizes via control of the reaction temperature and the irradiation wavelength. The results show that shorter excitation wavelengths and lower reaction temperatures result in high yields of nanodecahedra, while longer excitation wavelengths and higher reaction temperatures result in the formation of nanoprisms. The mechanism for the growth condition dependent evolution in the morphology of the silver particles is discussed as a kinetically controlled process. This is based on analysis of the reaction kinetics at various excitation wavelengths and temperatures. The energy barrier for the transformation from seeds to nanodecahedra is relatively high and requires a shorter wavelength. Thus longer wavelength illumination leads to the formation of nanoprisms. Thermodynamically stable five-fold twinning structures are shown to evolve from twin plane structures. The fast reaction rate at higher temperature favors the growth of nanoprisms by preferential Ag deposition on planar structures in a kinetics-controlled mode, while slower rates yield thermodynamically favored nanodecahedra.

Palladium porous single-crystalline nanoflowers (PSNFs) with enriched high catalytic activity {100} facets were synthesized using a mild and controllable seed mediated growth method. The growth mechanism of the Pd PSNFs was investigated using time dependent morphology evolution through TEM imaging. Due to the specific structure, Pd PSNFs show highly enhanced ethanol oxidation reaction (EOR) activity, high EOR anti-poisoning and stability, much better than Pd nanocubes, {111} facets dominated dendritic urchin-like Pd nanoparticles and Pd black.

•Shape effects on ORR were studied on Ag nanostructures with different facets.•The electrocatalytic activity is different on Ag nanodecahedra and nanocubes.•The adsorption competition between oxygen and hydroxyl is crucial for ORR on Ag.•The surface facet of Ag nanocrystals is important parameter to designing catalysts.The structure effects on the oxygen reduction reaction (ORR) are studied on similar sized silver nanodecahedra and nanocubes which are enclosed by (111) and (100) facets, respectively. The results show that the oxygen reduction proceeds one-step “direct” four-electron reduction on silver nanodecahedra, while two-step processes on silver nanocubes. The simulations results suggest that the different ORR catalytic activity can be interpretated by the adsorption competition between oxygen and hydroxyl on different silver facets. We demonstrate that the surface facet of silver nanocrystals is a decisive parameter to designing catalysts for ORR and other electrocatalytic reaction.

A surface plasmon resonance technique was used to systematically study the interaction of two dye molecules with graphene oxide (GO) and electrochemically reduced GO (EC-rGO) substrates. EC-rGO shows higher binding ability with both dyes than GO, possibly due to the molecular doping or π–π stacking. The results of SPR sensing are in agreement with the conclusions of fluorescence quenching experiments. This work may be valuable for graphene-related research work on optoelectronics and biosensors.

•Direct sensing of DNA/GO binding by a surface plasmon resonance technique.•Hydrogen bonding plays a key role in the interaction between GO and ssDNA.•Sensitive detection of DNA by combining AuNPs and graphene oxide with SPR.The binding of DNA with graphene oxide (GO) is important for applications in disease diagnosis, genetic screening, and drug discovery. The standard assay methods are mainly limited to indirect observation via fluorescence labeling. Here we report the use of surface plasmon resonance for direct sensing of DNA/GO binding. We show that this can be used for ultra-sensitive detection of single-stranded DNA (ssDNA). Furthermore, the results provide a more direct probe of DNA/GO binding abilities and confirm that hydrogen bonding plays a key role in the interaction between GO and ssDNA. This enables to a novel biosensor for highly sensitive and selective detection of ssDNA based on indirect competitive inhibition assay (ICIA). We report development of such a sensor with a linear dynamic range of 10−14–10−6 M, a detection limit of 10 fM and a high level of stability during repeated regeneration.

We report on a new and facile method for the preparation of well-dispersed gold-palladium (AuPd) flower-shaped nanostructures on sheets of graphene oxide (GO). Transmission electron microscopy and high angle annular dark field STEM were used to characterize the morphology and composition of the new nanohybrids. The AuPd/GO composites display high electrocatalytic activity for the oxidation of ethanol in strongly alkaline medium as examined by cyclic voltammetry and chronoamperometry. Both the current density (13.16 mA · cm−2 at a working potential of −0.12 V) and the long-time stability are superior to a commercial Pd-on-carbon catalyst which is attributed to the cooperative action of the catalytic activities of Au and Pd, and the good dispersion of the alloy on the nanosheets.

Controlling the assembly and manipulating the oxidation state of graphene nanosheets on surfaces are of essential importance for application of graphene-related optical and biosensing devices. In this study, we assemble a graphene oxide (GO) film on a surface plasmon resonance chip surface and then convert it to reduced graphene by an in situ electrochemical method. The mechanism and application of surface-enhanced Raman spectroscopy and DNA sensing from graphene-based substrates are investigated. The average thickness and dielectric constant of GO are varied significantly with the switch of its oxidation state. Electrochemical reduction decreases the distance between carbon atoms and the gold surface by removing the spacer of oxygen functional groups. The electromagnetic field of the graphene surface is therefore enhanced, resulting in an enhancement of the Raman signal. A p doping of electrochemically reduced GO (ERGO) that occurred from changes in the graphene electronic structure through interaction between gold and ERGO is also observed during electrochemical reduction. The GO and ERGO substrates perform different interaction abilities with single- and double-stranded DNA. This work may be valuable for graphene-related research works on optoelectronics and biosensors.Keywords: DNA binding; electrochemical reduction; graphene oxide; SERS; surface plasmon resonance;

The crystal engineering strategy was used to facilitate the supramolecular synthesis of a new crystalline phase of iloperidone, an atypical psychotropic drug with known problems related to poor dissolution and absorption profile. The novel crystal forms Jilin University China-Cocrystal-1 (JUC-C1), Jilin University China-Cocrystal-2 (JUC-C2), and Jilin University China-Cocrystal-3 (JUC-C3) of iloperidone with 3-hydroxybenzoic acid (3-HBA), 2,3-dihydroxybenzoic acid (2,3-DHBA), and 3,5-dihydroxybenzoic acid (3,5-DHBA) were obtained using the reaction crystallization method (RCM). The dissolution and pharmacokinetics studies were performed to exploit this atypical psychotropic drug. In the dissolution experiment, JUC-C1, JUC-C2, and JUC-C3 (JUC-C1–3) showed a much faster dissolution rate than the original active pharmaceutical ingredient (API) in simulated gastric fluid media (pH = 1.2). Furthermore, pharmacokinetic behavior of JUC-C1–3 and API was investigated to evaluate the effectiveness of this strategy for enhancing the oral absorption of iloperidone. The in vitro and in vivo studies revealed that JUC-C2 possessed an excellent dissolution behavior and improved pharmacokinetic profile.

A convenient and efficient preparation method for separation graphene oxide with well-defined size distribution is developed using a centrifugation technique. The graded profile of graphene oxide nanosheets with narrow size distribution is effectively controlled by varying the centrifugation speed. The results show that the oxygen content of graphene oxide is highly dependent on their size distribution. Graphene oxide nanosheet with large size shows a red-shift in UV–vis absorption spectra, compared to graphene oxide with small size. This phenomenon is interpretation by a density functional theory calculation. The present work will provide a simple method to prepare graphene oxide nanosheets with controllable size distribution and C/O ratio, which will be valuable for the functionalization of graphene-based hybrids and the fabrication of graphene nano-devices.Highlights► Well-defined size distribution of graphene oxide is developed using a centrifugation technique. ► The oxygen content of GO is highly dependent on their size distributions. ► UV–vis absorption spectrum shows a shift upon the size distribution. ► This phenomenon is interpreted by a density functional theory calculation.

●A novel hybrid of flower-shape palladium nanostructure/graphene oxide was formed.●The Pd nanostructure showed uniform size and well-dispersivity on the graphene oxide.●The hybrid will have broad applications in fuel cell, biosensing, and other fields.●The simple and effective composite platform could be extended to other nanohybrids.Flower-shape palladium nanostructures have been synthesized on the surface of graphene oxide by a simple effective method in the absence of any reducing chemical reagent. Atomic force microscopy (AFM), and Fourier transform infrared spectra (FT-IR) were used to characterize GO. The flower-shape palladium/Graphene oxide (FS-Pd/GO) nanocomposites are characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD). As-prepared FS-Pd/GO nanocomposites exhibited excellent performance on the electrocatalytic oxygen reduction reaction (ORR) and the glucose oxidation reaction. This method may open a general approach for preparing metal nanostructures on GO sheets for applications in fuel cells, biosensing and other fields.

Palladium nanoparticles with excellent uniform size and even distribution were prepared on graphene oxide (Pd NPs/GO) by using a simple and environmentally-friendly ultrasonic method in an ice bath. Ultrasonication time and composition ratios of GO and Pd influenced the morphology of the palladium nanoparticles and their electrocatalytic performance. Transmission electron microscopy (TEM) and electrochemical characterization demonstrated that GO acted as a good supportive substrate for controlling the size and activity of palladium nanoparticles. The optimized nanocomposite exhibited high electrochemical activity for electrocatalytic oxidation of glucose in alkaline medium. The Pd NPs/GO nanocomposite was developed as a non-enzymatic biosensor for the determination of glucose with a linear range of 0.2–10 mM, which is nearly insusceptible to common electroactive interfering species. This simple and effective composite platform could potentially be extended to other metal/graphene nanomaterials, and have broad applications in biosensing, fuel cells, and other fields.

The graphene/carbon nanotube hybrid was designed and implemented by a deoxygenation process for direct electron transfer of glucose oxidase and glucose biosensor. The procedure was analyzed by transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectra, etc. The strategy of structurally engineering one-dimensional carbon nanotube (CNT) and two-dimensional graphene oxide (GO) presented three benefits: (a) a deoxygenation process between GO and acid-CNT was introduced under strongly alkaline condition; (b) GO prevented the irreversible integration of CNT; and (c) CNT hindered the restacking of GO. The RGO interacted with CNT through the van der Waals forces and π–π stacking interaction. The three-dimensional hybrid not only had a high surface area, but also exhibited a good electronic conductivity. A direct electrochemistry of glucose oxidase was obtained on the nanohybrid modified electrode which showed good response for glucose sensing. This study would provide a facile and green method for the preparation of nanohybrid for a wide range of applications including biosensing, super capacitor, and transparent electrode.

Porous Pd nanotubes were in situ fabricated on a glass-carbon electrode (GCE) via a one-step galvanic replacement reaction by using cheap, flexible, and ultralong copper nanowires as the sacrificial template. The electrode exhibits excellent electrocatalytic performance for non-enzymatic glucose biosensors, thanks to massive pores and high specific surface area. This non-enzymatic glucose biosensor shows a wide linear response range from 5 μM to 10 mM, with a sensitivity of 6.58 μA mM−1 cm−2, and a detection limit of 1 μM (signal-to-noise ratio of 3).

Outstanding hydrogen evolution reaction (HER) activity and stability are highly desired for transition metal dichalcogenide (TMD)-based catalysts as Pt substitutes. Here, we theoretically calculated and experimentally showed that adsorbing Pd atoms on the basal plane of defect-rich (DR) MoS2 will effectively modulate the surface electronic state of MoS2 while retaining its active sites, which greatly enhanced the HER activity. Three decoration strategies were used to implement this design: direct epitaxial growth, assembling spherical nanoparticles and assembling Pd nanodisks (NDs). The results showed that only Pd NDs are able to be site-specifically decorated on the basal plane of DR-MoS2 through lamellar-counterpart-induced van der Waals pre-combination and covalent bonding. This Pd ND/DR-MoS2 heterostructure exhibits exceptional Pt-similar HER properties with a low onset-overpotential (40 mV), small Tafel slope (41 mV dec−1), extremely high exchange current density (426.58 μA cm−2) and robust HER durability. These results demonstrate a novel modification strategy by a lamellar metallic nanostructure for designing excellent layered TMD-based HER catalysts.