Silver Nanowires-Based Flexible Gold Electrode Overcoming Interior Impedance of Nanomaterial Electrodes.

In the development of nanomaterial electrodes for improved electrocatalytic activity, much attention is paid to the compositions, lattice, and surface morphologies. In this study, a new concept to enhance electrocatalytic activity is proposed by reducing impedance inside nanomaterial electrodes. Gold nanodendrites (AuNDs) are grown along silver nanowires (AgNWs) on flexible polydimethylsiloxane (PDMS) support. The AuNDs/AgNWs/PDMS electrode affords an oxidative peak current density of 50 mA cm-2 for ethanol electrooxidation, a value ≈20 times higher than those in the literature do. Electrochemical impedance spectroscopy (EIS) demonstrates the significant contribution of the AgNWs to reduce impedance. The peak current densities for ethanol electrooxidation are decreased 7.5-fold when the AgNWs are electrolytically corroded. By in situ surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) simulation, it is validated that the ethanol electrooxidation favors the production of acetic acid with undetectable CO, resulting in a more complete oxidation and long-term stability, while the AgNWs corrosion greatly decreases acetic acid production. This novel strategy for fabricating nanomaterial electrodes using AgNWs as a charge transfer conduit may stimulate insights into the design of nanomaterial electrodes.

Qualitative and quantitative electrochemiluminescence evaluation of trace Pt single-atom in MXenes.

The analysis of trace Pt single-atom (SA) represents a significant challenge, given the crucial role of single-atom platinum (Pt) in energy storage and electrocatalysis. Here, we present an electrochemiluminescence (ECL) platform that enables the qualitative and quantitative analysis of trace Pt SA using luminol as the ECL luminophore. It is observed that different Pt species in Ti3-xC2Ty MXenes resulted in distinct reactive oxygen species (ROS) potentials for luminol cathodic electrochemiluminescence (ECL), achieved through distinctive oxygen reduction reaction (ORR) pathways, in which oxygen acts as the co-reactant. Furthermore, the cathodic luminol ECL intensity increases in proportion to the Pt atom content, thereby enabling quantitative analysis of trace Pt single atoms. The detection limit is 0.014 wt%, which is comparable to the current mainstream Pt SA quantification techniques. By utilizing this ECL method, it is possible to successfully evaluate both qualitatively and quantitatively the changes in Pt SA during the ORR processes. This ECL platform provides a valuable toolbox for the analysis of Pt SA catalysts and for the evaluation of the mechanisms involved in electrocatalysis applications.

Highly sensitive label-free amperometric immunoassay of prostate specific antigen using hollow dendritic AuPtAg alloyed nanocrystals.

Herein, well-defined hollow dendritic AuPtAg alloyed nanocrystals (ANCs) were synthesized by a simple L-proline-mediated one-pot aqueous method. More importantly, the synthesized hollow dendritic architectures provide a suitable platform for immobilization of anti-prostate specific antigen (PSA). The resultant label-free immunosensor exhibited the improved performance for highly sensitive detection of PSA based on the enhanced catalytic currents of K3[Fe(CN)6] as a signal probe. Impressively, the immunosensor showed the wide linear range of 0.05-50 ng mL-1 and low detection limit of 0.017 ng mL-1 under optimal conditions for the assay of PSA, couple with the improved stability, reproducibility and selectivity. It provides a promising platform for clinical research and diagnosis.

Rapid fabrication of support-free trimetallic Pt53Ru39Ni8 nanosponges with enhanced electrocatalytic activity for hydrogen evolution and hydrazine oxidation reactions.

Herein, a rapid and straightforward coreduction aqueous approach was developed for preparation of support-free trimetallic Pt53Ru39Ni8 nanosponges with clean surface. Plenty of hydrogen bubbles were in situ formed via the oxidation and hydrolysis of the reductant (sodium borohydride), which served as the dynamic template in the fabrication of the porous sponge-like structures. The shape, size, crystal structure, and composition of the products were characterized by a set of characterization techniques. The obtained Pt53Ru39Ni8 nanosponges displayed dramatically highly electrocatalytic performances for hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HOR) outperformed home-made PtNi nanoparticles (PtNi NPs), RuNi NPs and commercial PtRu black (50wt.%). The present route provides new insights for facile synthesis of other bi-, tri- and even multi-metallic nanocatalysts for potential applications in catalysis, energy conversion and storage.

Simple synthesis of hierarchical AuPt alloy nanochains for construction of highly sensitive hydrazine and nitrite sensors.

Herein, a single-step co-reduction aqueous route was designed for preparation of hierarchical AuPt alloy nanochains, firstly using amprolium hydrochloride as a new stabilizing agent and structure-director. The morphology, structure, composition, and size of the products were characterized by a series of technique. The growth mechanism of AuPt nanochains was discussed in details. The AuPt nanochains modified glassy carbon electrode showed the improved analytical performances for determination of nitrite and hydrazine. The linear ranges of nitrite are 0.5-366.4µM and 466.4-2666.4µM for the two segments, and the detection limit is 0.03µM (S/N=3). The linear ranges of hydrazine are 5.0-116.4µM and 166.4-2666.4µM for the two segments, along with the low detection limit of 0.26µM (S/N=3). The performances of AuPt nanochains were superior to those of individual Pt and Au nanoparticles. It is ascribed to the specific hierarchical structures and synergistic effects of the bimetals.

l-Glutamic acid assisted eco-friendly one-pot synthesis of sheet-assembled platinum-palladium alloy networks for methanol oxidation and oxygen reduction reactions.

In this work, bimetallic platinum-palladium sheet-assembled alloy networks (PtPd SAANs) were facilely synthesized by an eco-friendly one-pot aqueous approach under the guidance of l-glutamic acid at room temperature, without any additive, seed, toxic or organic solvent involved. l-Glutamic acid was served as the green shape-director and weak-stabilizing agent. A series of characterization techniques were employed to examine the morphology, structure and formation mechanism of the product. The architectures exhibited improved electrocatalytic activity and durable ability toward methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in contrast with commercial Pt black and Pd black catalysts. This is ascribed to the unique structures of the obtained PtPd SAANs and the synergistic effects of the bimetals. These results demonstrate the potential application of the prepared catalyst in fuel cells.

Green-assembly of three-dimensional porous graphene hydrogels for efficient removal of organic dyes.

Herein, a facile and straightforward green-assembly approach was developed for preparation of nitrogen and sulphur co-doped three-dimensional (3D) graphene hydrogels (N/S-GHs) with the assistance of glutathione. Specifically, graphene oxide is reduced and assembled into 3D porous nanostructures with glutathione as the reducing agent and modifier for its intrinsic structure, along with the nitrogen and sulphur sources in the synthetic process. As expected, the as-obtained N/S-GHs demonstrated superior adsorption performances for organic dyes (e.g., methylene blue, malachite green, and crystal violet) in aqueous media. This work provides new insight for the green-assembly of 3D porous nanomaterials as adsorbent and their promising applications in water treatment.