Electron Transfer Kinetics Research Articles

Efficient Visible Light Photocatalytic Hydrogen Evolution by Boosting the Interfacial Electron Transfer in Mesoporous Mott-Schottky Heterojunctions of Co2P-Modified CdIn2S4 Nanocrystals.

Photocatalytic water splitting for hydrogen generation is an appealing means of sustainable solar energy storage. In the past few years, mesoporous semiconductors have been at the forefront of investigations in low-cost chemical fuel production and energy conversion technologies. Mesoporosity combined with the tunable electronic properties of semiconducting nanocrystals offers the desired large accessible surface and electronic connectivity throughout the framework, thus enhancing photocatalytic activity. In this work, we present the construction of rationally designed 3D mesoporous networks of Co2P-modified CdIn2S4 nanoscale crystals (ca. 5-6 nm in size) through an effective soft-templating synthetic route and demonstrate their impressive performance for visible-light-irradiated catalytic hydrogen production. Spectroscopic characterizations combined with electrochemical studies unravel the multipathway electron transfer dynamics across the interface of Co2P/CdIn2S4 Mott-Schottky nanoheterojunctions and shed light on their impact on the photocatalytic hydrogen evolution chemistry. The strong Mott-Schottky interaction occurring at the heterointerface can regulate the charge transport toward greatly improved hydrogen evolution performance. The hybrid catalyst with 10 wt % Co2P content unveils a H2 evolution rate of 20.9 mmol gcat -1 h-1 under visible light irradiation with an apparent quantum efficiency (AQE) up to 56.1% at 420 nm, which is among the highest reported activities. The understanding of interfacial charge-transfer mechanism could provide valuable insights into the rational development of highly efficient catalysts for clean energy applications.

Enhancing Ion Adsorption Capability through the Strong Interaction in Co9S8‐Carbon Hybrids Achieves Superior Sodium Ion Storage

AbstractMetal sulfides materials are promising anode candidates for Na+ storage due to their low cost and high theoretical capacity, while the complex phase transition and inevitable volume expansion during cycling restrain their practical applications. Herein, a simple one‐pot manipulation strategy was designed to construct Co9S8 nanoparticles strongly encapsulated in carbon nanotubes (Co9S8@C/NTs) composite structure with enhanced structural stability and reaction kinetics, resulting in greatly improved Na+ storage performance. Specifically, the obtained Co9S8@C/NTs could exhibit a remarkable capacity of 500 mAh g−1 at 0.5 A g−1 after 100 cycles and exceptional cycling stability over 600 cycles with 88 % capacity retention at 1 A g−1. Furthermore, the theoretical calculations combined with systematic characterizations confirm that the strong interaction between Co9S8 and the carbon matrix could greatly enhance the Na+ adsorption ability and facilitate the electron transfer dynamics for superior Na+ storage capability. More importantly, the full cell device can deliver an outstanding energy density of 144.32 Wh kg−1 and a decent cycling life with 82 % capacity retention of almost 100 cycles at 0.1 A g−1. This work could provide more valuable insights for designing advanced metal sulfide nanocomposites and demonstrate fascinating prospects for commercial application.

1T-rich MoS2 nanosheets anchored on conductive porous carbon as effective polysulfide promoters for lithium–sulfur batteries

The practical applications of lithium-sulfur (Li-S) batteries have severely been hindered by notorious shuttle effect and sluggish redox kinetics of lithium polysulfide intermediates (LiPSs), which bring about rapid capacity degradation, low coulombic efficiency and poor cycling stability. In this work, 1T-rich MoS2 nanosheets are in-situ developed onto the conductive porous carbon matrix (1T-rich MoS2@PC) as efficient polysulfide promotors for high-performance Li-S batteries. The porous carbon skeleton tightly anchors MoS2 nanosheets to prevent their reaggregation and ensures accessible electrical channels, and at the same time provides a favorable confined space that promotes the generation of 1T-rich MoS2 structure. More importantly, the uniformly distributed metallic 1T-rich MoS2 nanosheets not only affords rich sulfphilic sites and high binding energy for immobilizing LiPSs, but also favors rapid electron transfer and LiPSs conversation kinetics, substantially regulating sulfur chemistry in working cells. Consequently, the Li-S cell assembled with 1T-rich MoS2@PC modified separator delivers a remarkable cycling stability with ultralow capacity decay rate of 0.067% over 500 cycles at 1C. Encouragingly, under harsh conditions (high sulfur loading of 4.78 mg cm−2 and low E/S ratio of 8 μL mg−1), a favorable electrochemical performance can still be demonstrated. This study highlights the profitable design of 1T-rich MoS2/carbon based electrocatalyst for suppressing shuttle effect and promoting catalytic conversation of LiPSs, and has the potential to be applied to in other energy storage systems.

Cu2MoS4 Nanocatalyst-Based Electrochemical Sensor for Ofloxacin Electro-Oxidation: Delineating the Combined Roles of Crystallinity and Morphology on the Analytical Performance.

In this study, we demonstrate the influence of crystallinity and morphology on the analytical performance of various Cu2MoS4 (CMS) nanocatalysts-based electrochemical sensors for the high-efficiency detection of Ofloxacin (OFX) antibiotic. The electrochemical kinetics parameters including peak current response (ΔIp), peak-to-peak separation (ΔEp), electrochemically active surface area (ECSA), electron-transfer resistance (Rct), were obtained through the electrochemical analyses, which indicate the single-crystalline nature of CMS nanomaterials (NMs) is beneficial for enhanced electron-transfer kinetics. The morphological features and the electrochemical results for OFX detection substantiate that by tuning the tube-like to plate-like structures of the CMS NMs, it might noticeably enhance multiple adsorption sites and more intrinsic active catalytic sites due to the diffusion of analytes into the interstitial spaces between CMS nanoplates. As results, highly single-crystalline and plate-shaped morphology structures of CMS NMs would significantly enhance the electrocatalytic OFX oxidation in terms of onset potential (Eonset), Tafel slope, catalytic rate constant (kcat), and adsorption capacity (Γ). The CMS NMs-based electrochemical sensing platform showed excellent analytical performance toward the OFX detection with two ultra-wide linear detection concentration ranges from 0.25-100 and 100-1000 μM, a low detection limit of 0.058 μM, and an excellent electrochemical sensitivity (0.743 μA μM-1 cm-2).

Size-dependent electrochemistry of laser-induced graphene electrodes

Laser-induced graphene (LIG) electrodes have become popular for electrochemical sensor fabrication due to their simplicity for batch production without the use of reagents. The high surface area and favorable electrocatalytic properties also enable the design of small electrochemical devices while retaining the desired electrochemical performance. In this work, we systematically investigated the effect of LIG working electrode size, from 0.8 mm to 4.0 mm diameter, on their electrochemical properties, since it has been widely assumed that the electrochemistry of LIG electrodes is independent of size above the microelectrode size regime. The background and faradaic current from cyclic voltammetry (CV) of an outer-sphere redox probe [Ru(NH3)6]3+ showed that smaller LIG electrodes had a higher electrode roughness factor and electroactive surface ratio than those of the larger electrodes. Moreover, CV of the surface-sensitive redox probes [Fe(CN)6]3– and dopamine revealed that smaller electrodes exhibited better electrocatalytic properties, with enhanced electron transfer kinetics. Scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy showed that the physical and chemical surface structure were different at the electrode center versus the edges, so the electrochemical properties of the smaller electrodes were improved by having rougher surface, more density of the graphitic edge planes, and more oxide-containing groups. The difference could be explained by the different photothermal reaction time from the laser scribing process that causes different stable carbon morphology to form on the polymer surface. Our results give a new insight on relationships between surface structure and electrochemistry of LIG electrodes and are useful for designing miniaturized electrochemical devices.

Interface-modulated kinetic differentials in electron and hole transfer rates as a key design principle for redox photocatalysis by Sb2VO5/QD heterostructures.

The efficient conversion of solar energy to chemical energy represents a critical bottleneck to the energy transition. Photocatalytic splitting of water to generate solar fuels is a promising solution. Semiconductor quantum dots (QDs) are prime candidates for light-harvesting components of photocatalytic heterostructures, given their size-dependent photophysical properties and band-edge energies. A promising series of heterostructured photocatalysts interface QDs with transition-metal oxides which embed midgap electronic states derived from the stereochemically active electron lone pairs of p-block cations. Here, we examine the thermodynamic driving forces and dynamics of charge separation in Sb2VO5/CdSe QD heterostructures, wherein a high density of Sb 5s2-derived midgap states are prospective acceptors for photogenerated holes. Hard-x-ray valence band photoemission spectroscopy measurements of Sb2VO5/CdSe QD heterostructures were used to deduce thermodynamic driving forces for charge separation. Interfacial charge transfer dynamics in the heterostructures were examined as a function of the mode of interfacial connectivity, contrasting heterostructures with direct interfaces assembled by successive ion layer adsorption and reaction (SILAR) and interfaces comprising molecular bridges assembled by linker-assisted assembly (LAA). Transient absorption spectroscopy measurements indicate ultrafast (<2ps) electron and hole transfer in SILAR-derived heterostructures, whereas LAA-derived heterostructures show orders of magnitude differentials in the kinetics of hole (<100ps) and electron (∼1ns) transfer. The interface-modulated kinetic differentials in electron and hole transfer rates underpin the more effective charge separation, reduced charge recombination, and greater photocatalytic efficiency observed for the LAA-derived Sb2VO5/CdSe QD heterostructures.

Enhanced nitrite electroreduction to ammonia via interfacial dual-site adsorption

The nitrite (NO2−) to ammonia (NH3) electroreduction reaction (NO2−RR) would be impeded by sluggish proton-coupled electron transfer kinetics and competitive hydrogen evolution reaction (HER). A key to improving the NH3 selectivity is to facilitate adsorption and activation of NO2−, which is generally undesirable in unitary species. In this work, an efficient NO2−RR catalyst is constructed by cooperating Pd with In2O3, in which NO2− could adsorb on interfacial dual-site through “Pd–N–O–In” linkage, leading to strengthened NO2− adsorption and easier N=O bond cleavage than that on unitary Pd or In2O3. Moreover, the Pd/In2O3 composite exhibits moderate H* adsorption, which may facilitate protonation kinetics while inhibiting competitive HER. As a result, it exhibits a fairly high NH3 yield rate of 622.76 mmol h−1 g−1cat with a Faradaic efficiency (FE) of 95.72%, good selectivity of 91.96%, and cycling stability towards the NO2−RR, surpassing unitary In2O3 and Pd/C electrocatalysts. Besides, computed results indicate that NH3 production on Pd/In2O3 follows the deoxidation to hydrogenation pathway. This work highlights the significance of H* and NO2− adsorption modulation and N=O activation in NO2−RR electrochemistry by creating synergy between a mediocre catalyst with an appropriate cooperator.

Formation of Organic Monolayers on KF-Etched Si Surfaces

Silicon is the most commonly used material in the microelectronics industry, due to its inherent advantages of high natural abundance, low cost, and high purity, coupled with the chemical and electrical stability at the interface with its oxide. For molecular electronics applications, oxide-free Si surfaces are widely used because of the relative ease of removing the oxide (SiOx) by chemical means, yielding a surface which forms strong covalent bonds with a wide range of chemical functional groups; another advantage is that these surfaces remain oxide-free in the absence of oxidising agents. Standard procedures require the use of either HF, NH4F, or a mixture of both as the etching solution; however, these two chemicals are highly corrosive and toxic, posing a significant risk to the experimentalist. Here, we report that for silicon wafers etched by using potassium fluoride, a less toxic chemical, the resulting surface is free of oxides and can be functionalized by self-assembled monolayers of 1,8-nonadiyne. To demonstrate this, Si/SiOx wafers were etched by using either KF or NH4F, followed by hydrosilylation with 1,8-nonadiyne and a click reaction of the terminal alkyne with azidomethylferrocene. The surface coverages and electron transfer kinetics of the ferrocene-terminated KF-etched surfaces are comparable to those formed by acidic fluoride etching procedures. This is the first study comparing the differences between surfaces functionalized by self-assembled monolayers of 1,8-nonadiyne which were etched by KF and NH4F. KF could be used as a replacement chemical for etching silicon wafers when a less corrosive and toxic chemical is required.

White-Emitting Gold Nanocluster Assembly with Dynamic Color Tuning.

We report that constructed Au nanoclusters (NCs) can afford amazing white emission synergistically dictated by the Au(0)-dominated core-state fluorescence and Au(I)-governed surface-state phosphorescence, with record-high absolute quantum yields of 42.1% and 53.6% in the aqueous solution and powder state, respectively. Moreover, the dynamic color tuning is achieved in a wide warm-to-cold white-light range (with the correlated color temperature varied from 3426 to 24 973 K) by elaborately manipulating the ratio of Au(0) to Au(I) species and thus the electron transfer rate from staple motif to metal kernel. This study not only exemplifies the successful integration of multiple luminescent centers into metal NCs to accomplish efficient white-light emission but also inspires a feasible pathway toward customizing the optical properties of metal NCs by regulating electron transfer kinetics.

Monitoring of the prohibited 2-phenethylamine in dietary supplements using a t-Butyl calix[8]arene/Ag/CuO composite-based potentiometric sensor

2-phenethylamine (PEA) is a prohibited trace amine, that possesses amphetamine-like effect and toxicity. However, it is still present in many weight loss dietary supplements on which the quantities of PEA are not always listed. Therefore, monitoring of this toxic compound in these hypothetically safe products is essential. Herein, PEA was assayed using ion-selective potentiometric membrane sensors. A novel combination of silver doped copper oxide (Ag/CuO) nanoparticles with 4-tert-butylcalix[8]arene (BCX8) was investigated as a new ion-to-electron transducer layer used with solid contact glassy carbon electrodes. To study the effect of this novel combination, three sensors were proposed based on the incorporation of plain sodium tetraphenylborate (TPB) ion exchanger (sensor 1), TPB with BCX8 only (sensor 2) and TPB with Ag/CuO nanoparticles and BCX8 (sensor 3). The doped metal oxide nanoparticles were prepared using a simple wet co-precipitation synthesis procedure and were characterized for particle shape and size, elemental composition, and optical band gap energy. Near Nernstian responses were achieved with slope values of 52.28 ± 0.45, 54.64 ± 0.98 and 55.34 ± 0.35 mV/concentration decade and LOD of 9.88 × 10−5, 7.18 × 10−5, and 9.77 × 10−6 M for sensors 1, 2 and 3; respectively. Sensor 3 showed linearity range 1 × 10−5 to 1 × 10−2 M and response time of 10 s. The Ag/CuO nanoparticles incorporated within BCX8 network provided improved electron transfer kinetics, and was found to provide the best sensitivity, widest linearity range and the most stable and fastest response among the compared sensors. The proposed sensors showed excellent percent recoveries when applied for the analysis of PEA in its multi-ingredient formulation and showed no statistical difference with the reported method.

Elucidation of Design Criteria for V-based Redox Mediators: Structure-Function Relationships that Dictate Rates of Heterogeneous Electron Transfer.

Redox mediators are attractive solutions for addressing the stringent kinetic stipulations required for efficient energy conversion processes. In this work, we compare the electrochemical properties of four vanadium complexes, namely [V(acac)3], [V6O7(OMe)12], [nBu4N]3[V6O13(TRISNO2)2], and [nBu4N]5[V18O46(NO3)] in non-aqueous solutions on glassy carbon electrodes. The goal of this study is to investigate the electron transfer kinetics and diffusivity of these compounds under identical experimental conditions to develop an understanding of structure-function relationships that dictate the physicochemical properties of vanadium oxide assemblies. Complex selection was dictated by two criteria - (1) nuclearity of the transition metal complexes (2) distribution of electron density in the native electronic configuration. Our analyses establish that electronic communication between metal centers significantly impacts charge transfer kinetics of these vanadium-based compounds.

A Physical Insight of Phase-Dependent Electron Transfer Kinetic Behaviors and Electrocatalytic Activity of an Iron Oxide-Based Sensing Nanoplatform Towards Chloramphenicol

Insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures is important in the rational design of functional nanostructures for realizing high-performance electrochemical sensors. This study focuses on elucidating the effect of the crystalline phase on the electron transfer kinetics and electrocatalytic activity of iron(III) oxide. The α-FeOOH, γ-Fe2O3, and α-Fe2O3 nanorods were designed by using a simple chemical method and calcining process. The phase-dependent difference in the electron transfer kinetics and electrocatalytic activity toward the sensitive response of chloramphenicol (CAP) is observed by the transformation from α-FeOOH to γ-Fe2O3, and from α-FeOOH to α-Fe2O3 nanorods. We found that the oxygen vacancies formed in phase transformation from α-FeOOH to α-Fe2O3 is a key factor in promoting the electrochemical reduction of chloramphenicol. The α-Fe2O3 nanorods-based electrochemical sensors showed a linear response in the CAP concentration range from 0.1 to 75 μM with a limit of detection of 60 nM and an electrochemical sensitivity of 2.86 μA μM−1 cm−2. This work further provides valuable physical insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures for the rational design of sensing interface.

Optimized crystalline/amorphous NiFeS@NiMoP on nickel foam as dual-functional electrocatalysts for urea-water splitting

Urea electrolysis is a potential choice for generating hydrogen (H2) to fuel several purified energy technologies. In practice, the strategy for designing a transition metal sulfides (TMSs) phosphides (TMPs) electrocatalyst coupled with interfacial engineering applied into hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) is a extremely desirable and meaningful challenge. Herein, crystalline/amorphous heterostructure denoted as NiFeS@NiMoP/NF was made. Electrochemical tests show that：NiFeS@NiMoP/NF was active for both the HER and UOR process, which may due to the synergistic effect of Ni-based sulfides together with phosphides markely facilitated electron transfer and reaction kinetics and crystalline/amorphous structure provided ample unsaturated coordination configurations to enhance the adsorption of reactants. Impressively, NiFeS@NiMoP/NF displays comparatively low overpotential with value of 56.4 mV for HER and potential of 1.32 V for UOR to deliver the current density of 10 mA cm−2, and drives the overall splitting of urea-water electrolysis at 1.40 V in 1.0 M KOH +0.5 M urea at 10 mA cm−2. This approach may shed light on the designing and developing crystalline/amorphous bifunctional materials for energy conversion and application.

Modification of Zinc Tungstate with Functionalized Carbon Nanofibers for Electrochemical Detection of 3-Nitro-L-Tyrosine in Tap Water and Bovine Serum Albumin

Abstract Precise revealing and early detection of 3-Nitro-L-Tyrosine (3-NLT), a biomarker of oxidative stress in biological media is critical for the early treatment of cancer tumorigenic cells and immunologic disorders. In this study, zinc tungstate (ZnWO4) was incorporated with functionalized carbon nanofibers (f-CNF) to form a ZnWO4/f-CNF composite. The composite improves detection of 3-NLT by increasing the electrical conductivity, electrocatalytic activity, and rapid electron transfer kinetics. Various physical characterization techniques were employed to confirm the ZnWO4/f-CNF composite. Electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry were utilized to detect 3-NLT after modifying ZnWO4/f-CNF on glassy carbon electrode (GCE). The ZnWO4/f-CNF/GCE achieved an elevated electrochemically active surface area (0.08 cm2), a linear range of 1.0-117.0 µM, and a low detection limit of 0.07 µM. Finally, the ZnWO4/f-CNF/GCE was tested with bovine serum albumin and tap water in the real sample investigation.

Bismuth-Doped Carbon Dots Decorated Escherichia coli for Enhanced Hydrogen Production.

Photosynthetic inorganic biohybrid systems (PBSs) combining an inorganic photosensitizer with intact living cells provide an innovative view for solar hydrogen production. However, typical whole-cell biohybrid systems often suffer from sluggish electron transfer kinetics during transmembrane diffusion, which severely limits the efficiency of solar hydrogen production. Here, a unique biohybrid system with a quantum yield of 8.42% was constructed by feeding bismuth-doped carbon dots (Bi@CDS) to Escherichia coli (E.coli). In this biohybrid system, Bi@CDS can enter the cells and transfer the electrons upon light irradiation, greatly reducing the energy loss and shortening the distance of electron transfer. More importantly, the photocatalytic hydrogen production of the E.coli-Bi@CDs biohybrid system reached up to 0.95 mmol within 3 h under light irradiation (420-780 nm, 2000 W m-2), which is 1.36 and 2.38 times higher than that in the E.coli-CDs biohybrid system and the E.coli system, respectively. In addition, the mechanism of enhanced hydrogen production was further explored. It was found that the accelerated decomposition of glucose, the accelerated production of pyruvate, the inhibition of lactic acid, and the increase of formic acid were the reasons for the increase of hydrogen production. This work provides a novel strategy for improving the hydrogen production in photosynthetic inorganic biohybrid systems.

Electrocatalytic sensing of propyl gallate in real-time food samples using a synergistic Sm-MOF@GCN composite modified glassy carbon electrode

A novel electrochemical sensor has been developed using the sonochemically synthesized samarium metal–organic framework (Sm-MOF) and the graphitic carbon nitride (GCN) composite for the selective determination of propyl gallate (PG). The as-synthesized Sm-MOF@GCN composite was characterized by XRD, XPS, and FESEM. The morphological studies of the prepared Sm-MOF@GCN composite revealed the bar-shaped Sm-MOF and porous sheet-like morphology of GCN. The combined effect of the Sm-MOF and GCN enhance the current density response and lowers the oxidation potential, which was beneficial for the electrochemical sensing of PG. Moreover, the high electrochemical active surface area (EASA) (0.0649 cm2) and the rate constant value (Ko) of 1.44x10-5 cm s−1 confirm the faster electron transfer kinetics at the interface of Sm-MOF@GCN composite. However, the developed Sm-MOF@GCN composite possesses linear range from 0.02 to 60 µM with a nanomolar detection level (2.05 nM), high sensitivity (0.1914 μA μM−1 cm−2), excellent reproducibility, repeatability, and stability for up to 30 days towards the PG detection. Finally, the Sm-MOF@GCN composite-modified electrocatalyst was utilized for the quantification of PG in foodstuffs such as instant noodles, cookies, cakes, and oils. The result of the study, the Sm-MOF@GCN composite displayed good recovery results, making it a promising candidate for detecting PG in real-world samples in view of its binder-free approach and facile fabrication process.

Leveraging Direct Pyrolysis for the Synthesis of 10 nm Monodispersed Fe3O4/Fe3C NPS@Carbon to Improve SupercapacitANCE in Acidic Electrolyte.

The prevailing practice advocates pre-oxidation of electrospun Fe-salt/polymer nanofibers (Fe-salt/polymer Nf) before pyrolysis as advantageous in the production of high-performance FeOx@carbon nanofibers supercapacitors (FeOx@C). However, our study systematically challenges this notion by demonstrating that pre-oxidation facilitates the formation of polydispersed and large FeOx nanoparticles (FeOx@CI-DA) through "external" Fe3+ Kirkendall diffusion from carbon, resulting in subpar electrochemical properties. To address this, direct pyrolysis of Fe-salt/polymer Nf is proposed, promoting "internal" Fe3+ Kirkendall diffusion within carbon and providing substantial physical confinement, leading to the formation of monodispersed and small FeOx nanoparticles (FeOx@CDA). In 1 M H2SO4, FeOx@CDA demonstrates ~2.60× and 1.26× faster SO4 2- diffusivity, and electron transfer kinetics, respectively, compared to FeOx@CI-DA, with a correspondingly ~1.50× greater effective surface area. Consequently, FeOx@CDA exhibits a specific capacity of 161.92 mAhg-1, ~2× higher than FeOx@CI-DA, with a rate capability ~19 % greater. Moreover, FeOx@CDA retains 94 % of its capacitance after 5000 GCD cycles, delivering an energy density of 26.68 Whkg-1 in a FeOx@CDA//FeOx@CDA device, rivaling state-of-the-art FeOx/carbon electrodes in less Fe-corrosive electrolytes. However, it is worth noting that the effectiveness of direct pyrolysis is contingent upon hydrated Fe-salt. These findings reveal a straightforward approach to enhancing the supercapacitance of FeOx@C materials.

Reinforcing 2D Single-Crystal Bi2O2CO3 with Additional Interlayer Carbonates by CO2-Assisted Solid-to-Solid Phase Transition.

A facile gaseous CO2 mediated solid-to-solid transformation principle is adopted to insert additional CO3 2- anions into the thin single-crystal nanosheets of Bi2O2CO3, which is built of periodic arrays of intrinsic CO3 2- anions and (Bi2O2)2+ layers. The additional CO3 2- anions create abundant defects. The Bi2O2CO3 nanosheets with rich interlayer CO3 2- exhibit superior electronic properties and charge transfer kinetics than the pristine single-crystal 2D Bi2O2CO3 and display enhanced catalytic activity in photocatalytic CO2 reduction reaction and the photocatalytic oxidative degradation of organic pollutants. This work thus illustrates interlayer engineering as a flexible means to build layered 2D materials with excellent properties.

Tunability in 3-Site Electronic Excitation Transfer Dynamics: Insights into the Role of Perturbative Coupling.

Electronic excitation transfer dynamics in photosynthetic systems, including the Fenna-Matthews-Olson complex, are often modeled using the interaction picture of three two-level systems, also known as the 3-site system. Among the two possible configurations, uphill and downhill, a recent publication reported an intriguing correlation between population dynamics and the intersite coupling. Specifically, the uphill configuration has been shown to have a pronounced dependence on perturbations in the intersite coupling, whereas the downhill configuration displays negligible dependence. In this study, we consider a generic 3-site configuration and model site interactions through the Markovian master equation. Through this approach, we derive succinct analytical expressions for the population dynamics between the sites, shedding light on the differences in behavior between the two configurations. Using these analytical expressions, we demonstrate the range of tunability in population dynamics achievable with minimal changes in intersite coupling, and we validate these findings through simulation results. These insights into the population dynamics of a 3-site system are expected to play a crucial role in facilitating the design of efficient energy-transfer pathways in molecular systems.

Innovative electrochemical sensor based on Fe3O4@Fe-BTC nanocomposite to sensitive determination of 4-nitrophenol

The Fe3O4@Fe-BTC nanocomposite has been thoroughly investigated in this study. The synthesis of Fe-BTC framework has involved a solvothermal method, while Fe3O4 NPs have been prepared using a coprecipitation technique. The resulting materials have been characterized using various techniques (XRD, FT-IR spectra, and SEM images). The electrochemical behaviors have been analyzed using CV and EIS. More interestingly, the electrochemical performance of 4-nitrophenol (4-NP) has also been investigated on the various modified electrodes via CV, DPV, and CA measurements in a 0.1 M PBS buffer by studying the electrochemical reduction of 4-NP. Remarkably, the Fe3O4@Fe-BTC nanocomposites have exhibited enhanced electrochemical properties when compared with the individual Fe3O4 and Fe-BTC components. This improvement could be attributed to the synergistic effects of the highly porous Fe-BTC and the magnetic Fe3O4 NPs, leading to enhanced electron transfer kinetics and electrocatalytic activity. These findings underscore the potential of designed nanocomposite materials for various electrochemical applications.