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Streszczenie:
Vacancy engineering offers an attractive approach to improving the surface properties and electronic
structure of transition metal nanomaterials. However, simple and cost-effective methods for introducing
defects into nanomaterials still face great challenges. Herein, we propose a facile room temperature
two-step technique that utilizes Fe as the dopant to enhance S vacancies in cobalt-based metal–organic
frameworks (MOFs). The Fe–Co-MOF was converted into a hollow Fe–Co3S4 confined in CoMo2S4 to
form Fe–Co3S4@CoMo2S4 nanosheets. The as-prepared material showed enhanced charge storage
kinetics and excellent properties as an electrode material for supercapacitors. The obtained
nanostructure displayed a high specific capacitance (980.3 F g−1 at 1 A g−1) and excellent cycling stability
(capacity retention of 96.5% after 6000 cycles at 10 A g−1). Density functional theory (DFT) calculations
show that introducing defects into the nanostructures leads to more electrons appearing near the Fermi
level, which is beneficial for electron transfer during electrochemical processes. Thus, this work provides
a rational cost-effective strategy for introducing defects into transition metal sulfides and may serve as
a potential means to prepare electrode materials for energy storage.

Streszczenie:
The rational synthesis and tailoring of metal-organic frameworks (MOFs) with multifunctional micro/nanoarchitectures have emerged as a subject of significant academic interest owing to their promising potential for utilization in advanced energy storage devices. Herein, we explored a category of three-dimensional (3D) NiCo2S4 nanospikes that have been integrated into a 1D Fe3C microarchitecture using a chemical surface transformation process. The resulting electrode materials, i.e., Fe3C@NiCo2S4 nanospikes, exhibit immense potential for utilization in high-performance hybrid supercapacitors. The nanospikes exhibit an elevated specific capacity (1894.2 F g-1 at 1 A g-1), enhanced rate capability (59%), and exceptional cycling stability (92.5% with 98.7% Coulombic efficiency) via a charge storage mechanism reminiscent of a battery. The augmented charge storage characteristics are attributed to the collaborative features of the active constituents, amplified availability of active sites inherent in the nanospikes, and the proficient redox chemical reactions of multi-metallic guest species. When using nitrogen-doped carbon nanofibers as the anode to fabricate hybrid supercapacitors, the device exhibits high energy and power densities of 62.98 Wh kg-1 and 6834 W kg-1, respectively, and shows excellent long-term cycling stability (95.4% after 5000 cycles), which affirms the significant potential of the proposed design for applications in hybrid supercapacitors. The DFT study showed the strong coupling of the oxygen from the electrolyte OH- with the metal atom of the nanostructures, resulting in high adsorption properties that facilitate the redox reaction kinetics.

Słowa kluczowe:
defect engineering, Nanospike, advanced electrode, hybrid, MOF, Supercapacitor

Streszczenie:
Fe-based nanostructures have possessed promising properties that make it suitable for chiral sensing and imaging applications owing to their ultra-small size, non-toxicity, biocompatibility, excellent photostability, tunable fluorescence, and water solubility. This review summarizes the recent research progress in the field of Fe-based nanostructures and places special emphases on their applications in chiral sensing and imaging. The synthetic strategies to prepare the targeted Fe-based structures were also introduced. The chiral sensing and imaging applications of the nanostructures are discussed in details.

Streszczenie:
Tuning the electronic structure of single-atom catalysts through dimeric single-atom formation could be an innovative approach to increasing their energy storage activity, but the process of achieving this is challenging. In this study, we designed a simple technique to obtain Nisingle bondCo single atom dimers (SADs) anchored on N-doped molybdenum carbide (N-Mo2C) through in-situ encapsulation of Nisingle bondCo into molybdenum polydopamine, followed by annealing with optimal tuning of nitrogen dopant. The Nisingle bondCo atomic level coordination was confirmed with X-ray absorption spectroscopy. When used as energy storage supercapacitor, The NiCo-SADs showed enhanced specific capacity (1004.8 F g−1 at 1 A g−1), enhanced rate capability (75 %), and exceptional cycling stability (93.6 % with 98.5 % coulombic efficiency) via a dominant capacitive charge storage. The augmented charge storage characteristics are attributed to the collaborative features of the active Nisingle bondCo constituents acting as electron reservoir for effective adsorption of HO− ion during the electrochemical process. The DFT study showed thermodynamically favorable OH− adsorption between the three metal bridges that promoted redox reaction kinetics and enhanced conductivity for the NiCo-SADs. When using N-Mo2C as the anode to fabricate hybrid supercapacitors, the device exhibits high energy density of 69.69 Wh kg−1 at power density of 8200 W kg−1, respectively and shows excellent long-term cycling stability (93.42 % after 3000 cycles), which affirms the potential of the assembled device for applications in solid state supercapacitors.

Streszczenie:
A feasible nanoscale framework of heterogeneous plasmonic materials and
proper surface engineering can enhance photoelectrochemical (PEC)
water-splitting performance owing to increased light absorbance, efficient
bulk carrier transport, and interfacial charge transfer. This article introduces a
new magnetoplasmonic (MagPlas) Ni-doped Au@FexOy nanorods (NRs)
based material as a novel photoanode for PEC water-splitting. A two stage
procedure produces core–shell Ni/Au@FexOy MagPlas NRs. The first-step is
a one-pot solvothermal synthesis of Au@FexOy. The hollow FexOy nanotubes
(NTs) are a hybrid of Fe2O3 and Fe3O4, and the second-step is a sequential
hydrothermal treatment for Ni doping. Then, a transverse magnetic
field-induced assembly is adopted to decorate Ni/Au@FexOy on FTO glass to
be an artificially roughened morphologic surface called a rugged forest,
allowing more light absorption and active electrochemical sites. Then, to
characterize its optical and surface properties, COMSOL Multiphysics
simulations are carried out. The core–shell Ni/Au@FexOy MagPlas NRs
increase photoanode interface charge transfer to 2.73 mAcm−2 at 1.23 V RHE.
This improvement is made possible by the rugged morphology of the NRs,
which provide more active sites and oxygen vacancies as the hole transfer
medium. The recent finding may provide light on plasmonic photocatalytic
hybrids and surface morphology for effective PEC photoanodes.

Streszczenie:
The integration of different precursor components to form single nanostructures via one-step synthesis process is mostly restricted by the compatibility and complexity of components. Herein, a highly uniform, spherical, hollowed, and hierarchical iron oxide-wrapped Mo–polydopamine is synthesized using a one-pot liquid-phase reaction at room temperature. Mo2C is doped with Fe3O4 to harness the rich electrons in Fe dopants for effective lowering of the unoccupied d-orbitals in Mo. The surface conductivity of the as-prepared nanostructures is enhanced by decorating them with gold nanoparticles utilizing strong interaction of Au and amine. The nanocomposites are converted into carbidic hollowed structures via an annealing process without any distortion in morphology. The well-organized structure and nanosize of the particles provide efficient catalytic performance for hydrogen evolution reaction in acidic media. MoFe–C@Au exhibits a very positive onset potential of 2 mV, low Tafel slope of 50.1 mV dec^-1, and remarkable long- term stability.

Słowa kluczowe:
electrocatalysts,hierarchical syntheses,hydrogen evolution,molybdenum,polydopamine

Streszczenie:
Hydrogen produced by electrochemical water splitting is considered to be a sustainable fuel source, an
ideal way to solve the energy problem and its environmental challenges. However, industrial production
of hydrogen from water splitting is mainly hindered by sluggish kinetics of the oxygen evolution reaction
(OER) at the anode and the hydrogen evolution reaction (HER) at the cathode in an alkaline solution due
to the difficulty in forming binding protons. Thus, the construction of a highly active and cost-effective
catalyst with abundant oxygen vacancies is critical for enhancing the reaction efficiency and decreasing
the required overpotential. Due to earth-abundance and electrocatalytic activities, Ni-based ultrathin
nanostructures (Ni-utNSs) have attracted immense attention for overall water splitting. Herein, we have
presented a complete summary of recent advancements in Ni-utNSs for overall electrochemical water
splitting. After discussing unique advances in Ni-utNSs, we discussed their properties and crystal
structures. The HER, OER, and oxygen reduction reaction (ORR) mechanisms were briefly discussed. We
also discussed several Ni-utNS manufacturing techniques, as well as in situ and ex situ characterization
and computer modeling. Furthermore, the electrochemical water splitting of Ni-utNSs is addressed. This
review can help readers understand the recent progress of Ni-utNS catalysts and gain insight into the
rational design of Ni-utNS catalysts with high electrocatalytic activity.

Streszczenie:
The global pandemic of COVID-19 is an example of how quickly a disease-causing virus can take root and threaten our civilization. Nowadays, ultrasensitive and rapid detection of contagious pathogens is in high demand. Here, we present a novel hierarchically porous 3-dimensional magnetic molybdenum trioxide–polydopamine-gold functionalized nanosphere (3D mag-MoO3–PDA@Au NS) composed of plasmonic, semiconductor, and magnetic nanoparticles as a multifunctional nanosculptured hybrid. Based on the synthesized 3D mag-MoO3–PDA@Au NS, a universal “plug and play” biosensor for pathogens is proposed. Specifically, a magnetically-induced nanogap-enhanced Raman scattering (MINERS) detection platform was developed using the 3D nanostructure. Through a magnetic actuation process, the MINERS system overcomes Raman signal stability and reproducibility challenges for the ultrasensitive detection of SARS-CoV-2 spike protein over a wide dynamic range up to a detection limit of 10−15 g mL−1. The proposed MINERS platform will facilitate the broader use of Raman spectroscopy as a powerful analytical detection tool in diverse fields.

Streszczenie:
We study the impact of inlet channel geometry on microfluidic drop formation. We show that drop makers with T-junction style inlets form monodisperse emulsions at low and moderate capillary numbers and those with Flow-Focus style inlets do so at moderate and high capillary numbers. At low and moderate capillary number, drop formation is dominated by interfacial forces and mediated by the confinement of the microchannels; drop size as a function of flow-rate ratio follows a simple functional form based on a blocking-squeezing mechanism. We summarize the stability of the drop makers with different inlet channel geometry in the form of a phase diagram as a function of capillary number and flow-rate ratio.