NMR Immunosensor Based on a Targeted Gadolinium Nanoprobe for Detecting Salmonella in Milk.

Detecting harmful pathogens in food is not only a crucial aspect of food quality management but also an effective way to ensure public health. In this paper, a complete nuclear magnetic resonance biosensor based on a novel gadolinium (Gd)-targeting molecular probe was developed for the detection of Salmonella in milk. First, streptavidin was conjugated to the activated macromolecular polyaspartic acid (PASP) via an amide reaction to generate SA-PASP. Subsequently, the strong chelating and adsorption properties of PASP toward the lanthanide metal gadolinium ions were exploited to generate the magnetic complex (SA-PASP-Gd). Finally, the magnetic complex was linked to biotinylated antibodies to obtain the bioprobe and achieve the capture of Salmonella. Under optimal experimental conditions, the sensor we have constructed can achieve a rapid detection of Salmonella within 1.5 h, with a detection limit of 7.1 × 103 cfu mL-1.

Rapid detection of Salmonella in milk by labeling-free electrochemical immunosensor based on an Fe3O4-ionic liquid-modified electrode.

Electrochemical sensors show distinct advantages over other types of sensors in the rapid detection of microorganisms. Here, we attempted to construct a label-free electrochemical immunosensor based on an Fe3O4-ionic liquid (IL)-modified electrode to rapidly detect Salmonella in milk. The excellent ionic conductivity of the IL facilitated sensor construction, and the large surface area of nano-Fe3O4 provided numerous sites for subsequent experiments. An antibody was fixed on the Fe3O4-IL complex with polyglutamic acid modification by a simple infusion method. The microstructure of the Fe3O4-IL composites was investigated by scanning electron microscopy, and the elements and structures of the composites were analyzed by energy dispersive X-ray and Fourier transform infrared spectroscopy. Under optimized experimental conditions, the detection range of the constructed sensor was 3.65 × 102-3.65 × 108 CFU mL-1, and the LOD was 1.12 × 102 CFU mL-1 (S/N = 3). In addition, the prepared electrochemical immunosensor is convenient for detecting foodborne pathogens because of its outstanding stability, good selectivity, and repeatability.

Facile and Stable CuInO2 Nanoparticles for Efficient Electrochemical CO2 Reduction.

Searching for electrocatalysts for the electrochemical CO2 reduction reaction (e-CO2RR) with high selectivity and stability remains a significant challenge. In this study, we design a Cu-CuInO2 composite with stable states of Cu0/Cu+ by electrochemically depositing indium onto CuCl-decorated Cu foil. The catalyst displays superior selectivity toward the CO product, with a maximal Faraday efficiency of 89% at -0.9 V vs the reversible hydrogen electrode, and maintains impressive stability up to 27 h with a retention rate of >76% in Faraday efficiency. Our systematical characterizations reveal that the catalyst's high performance is attributed to CuInO2 nanoparticles. First-principles calculations further confirm that CuInO2(012) is more conducive to CO generation than Cu(111) under applied potential and presents a higher energy barrier than Cu(111) for the hydrogen evolution reaction. These theoretical predictions are consistent with our experimental observations, suggesting that CuInO2 nanoparticles offer a facile catalyst with a high selectivity and stability for e-CO2RR.

Decoding the Mechanisms of Reversibility Loss in Rechargeable Zinc-Air Batteries.

Attaining high reversibility of the electrodes and electrolyte is essential for the longevity of secondary batteries. Rechargeable zinc-air batteries (RZABs), however, encounter drastic irreversible changes in the zinc anodes and air cathodes during cycling. To uncover the mechanisms of reversibility loss in RZABs, we investigate the evolution of the zinc anode, alkaline electrolyte, and air electrode through experiments and first-principles calculations. Morphology diagrams of zinc anodes under versatile operating conditions reveal that the nanosized mossy zinc dominates the later cycling stage. Such anodic change is induced by the increased zincate concentration due to hydrogen evolution, which is catalyzed by the mossy structure and results in oxide passivation on electrodes and eventually leads to low true Coulombic efficiencies and short life spans of batteries. Inspired by these findings, we finally present a novel overcharge-cycling protocol to compensate for the Coulombic efficiency loss caused by hydrogen evolution and significantly extend the battery life.

Refinement of nanoporous copper by dealloying the Al-Cu alloy in NaOH solution containing sodium dodecyl sulfate.

This work reports the refinement of nanoporous copper (NPC) ligaments by introducing the sodium dodecyl sulfate (SDS) surfactant in the dealloying process. The Al80Cu20 (at%) alloy precursor is chemically dealloyed in a mixed solution of NaOH and SDS surfactant, producing NPC with a hierarchical microstructure. Micron-scaled skeletons that build up higher level networks consist of geometrically similar nano-scaled bi-continuous ligament-pore networks at the lower level. It has been found that the size of the ligaments in the lower level networks reduces from ∼32 nm to ∼24 nm with increasing SDS concentration to 1 mM. Further increasing the SDS concentration to 5 mM only leads to a slight ligament size decrease to ∼21 nm. Remarkably, nano-sized cones are formed on the lower level network surface in the dealloying solution containing 1 mM SDS, and the cone number greatly rises when the SDS concentration increases to 5 mM. The surface diffusivity of Cu adatoms is evaluated based on the experimental data, and the refinement of the ligament as well as the formation of cones are associated with the decreased surface diffusivity and the retarded Cu adatom motions with the addition of SDS. Quantum chemical calculations and molecular dynamics simulations are performed to model the adsorption behavior of SDS. It has been found that the SDS-substrate interaction increases with the number of SDS molecules before SDS reaches saturation.

Homogenizing Zn Deposition in Hierarchical Nanoporous Cu for a High-Current, High Areal-Capacity Zn Flow Battery.

A Zn anode can offset the low energy density of a flow battery for a balanced approach toward electricity storage. Yet, when targeting inexpensive, long-duration storage, the battery demands a thick Zn deposit in a porous framework, whose heterogeneity triggers frequent dendrite formation and jeopardizes the stability of the battery. Here, Cu foam is transferred into a hierarchical nanoporous electrode to homogenize the deposition. It begins with alloying the foam with Zn to form Cu5 Zn8 , whose depth is controlled to retain the large pores for a hydraulic permeability ≈10-11  m2 . Dealloying follows to create nanoscale pores and abundant fine pits below 10 nm, where Zn can nucleate preferentially due to the Gibbs-Thomson effect, as supported by a density functional theory simulation. Morphological evolution monitored by in situ microscopy confirms uniform Zn deposition. The electrode delivers 200 h of stable cycles in a Zn-I2 flow battery at 60 mAh cm-2 and 60 mA cm-2 , performance that meets practical demands.

Constructing stable covalent bonding in black phosphorus/reduced graphene oxide for lithium ion battery anodes.

Strong covalent bonds were in situ constructed in a unique black phosphorus (BP) @ reduced graphene oxide nanocomposite via a facile and scalable high energy ball-milling process, which contributes to the high specific capacity of BP@irGO and tackles the long-standing problem of large volume expansion of high capacity electrode matrerials.

Flexible Membrane Consisting of MoP Ultrafine Nanoparticles Highly Distributed Inside N and P Codoped Carbon Nanofibers as High-Performance Anode for Potassium-Ion Batteries.

Rechargeable potassium-ion batteries (PIBs) have attracted tremendous attention as potential electrical energy storage systems due to the special merit of abundant resources and low cost of potassium. However, one critical barrier to achieve practical application of PIBs has been the lack of suitable electrode materials. Here, a novel flexible membrane consisting of N, P codoped carbon nanofibers decorated with MoP ultrafine nanoparticles (MoP@NPCNFs) is fabricated via a simple electrospinning method combined with the later carbonization and phosphorization process. The 3D porous CNF structure in the as-synthesized composite can shorten the transport pathways of K-ions and improve the conductivity of electrons. The ultrafine MoP nanoparticles can guarantee high specific capacity and the N, P co-doping could improve wettability of electrodes to electrolytes. As expected, the free-standing MoP@NPCNF electrode demonstrates a high capacity of 320 mAh g-1 at 100 mA g-1 , a superior rate capability maintaining 220 mAh g-1 at 2 A g-1 , as well as a capacity retention of more than 90% even after 200 cycles. The excellent rate performance, high reversible capacity, long-term cycling stability, and facile synthesis routine make this hybrid membrane promising anode for potassium-ion batteries.