Interfacial Electron Transfer Processes Research Articles

Electron transfer controlled by solvent and counter-anion dynamics in electrochemistry of viologen-type ionic liquid

Temperature-dependent diffusion coefficients (DO) and heterogeneous electron transfer rate constants (k0) were measured for the viologen dication (V2+) in 1-butyl-1′-heptyl-4,4′-bipyridinium bis[(trifluoromethane)sulfonyl]imide [C4VC7][Tf2N]2 redox-active ionic liquid (RAIL) and its solution. The measurements were made in three systems: (1) 10 mM of [C4VC7][Tf2N]2 dissolved in 0.1 M K[Tf2N]/acetonitrile (an organic electrolyte), (2) 10 mM [C4VC7][Tf2N]2 dissolved in a 1-n-hexyl-3-methylimidazolium tris(pentafluoroethyl)-trifluorophosphate, [HMIm][FEP] ionic liquid (IL) (an ionic liquid (IL) electrolyte), and (3) the undiluted RAIL of 1.68 M [C4VC7][Tf2N]2 with no additional solvents or supporting electrolytes. At 25 °C, the DO values in systems (1), (2), and (3) were 8.2 × 10−6, 6.7 × 10−8, and 1.3 × 10−9 cm2 s−1, and the k0 values were 1.1 × 10−2, 3.6 × 10−3, and 2.0 × 10−5 cm s−1, respectively. Temperature-dependent DO and k0 values were further interrelated to investigate heterogeneous interfacial electron transfer processes in systems (2) and (3). Solvent dynamics and counter-ion relaxation processes were used to describe the results. In system (3), k0 values were proportional to both DO and counter-ion diffusion coefficients (DCIon) but inversely proportional to the viscosity (η). Moreover, almost the same magnitude of thermal activation barrier (∼64 kJ mol−1) was found for k0, DO, DCIon, and η−1 in the system (3). In system (2), k0 values showed a non-linear relationship with DO, DCIon and η−1, and a thermal activation barrier was found to be 22.2 kJ mol−1. These results enabled us to conclude that the V+/V2+ heterogeneous electron transfer in system (3) is controlled concurrently by solvent dynamics (segmental motion of alkyl chains attached to viologen centers) and electro-inactive counter anion motion. This work reveals an inherent dependency of heterogeneous electron transfer kinetics on the solvent and counter-ion dynamics in viologen IL systems.

Nonadiabatic Dynamics Simulations Reveal Distinct Effects of the Thickness of PTB7 on Interfacial Electron and Hole Transfer Dynamics in PTB7@MoS2 Heterostructures.

Mixed-dimensional hybrid heterostructures have attracted a lot of experimental attention because they can provide an ideal charge-separated interface for optoelectronic and photonic applications. In this Letter, we have employed first-principles DFT calculations and nonadiabatic dynamics simulations to explore photoinduced interfacial electron and hole transfer processes in two PTB7- nL@MoS2 models ( n = 1 and 5). The interfacial electron transfer is found to be ultrafast and completes within ca. 10 fs in both PTB7-1L@MoS2 and PTB7-5L@MoS2 models, which demonstrates that the electron transfer is not sensitive to the thickness of the PTB7 polymer. Differently, the interfacial hole transfer is sensitive to the thickness of the PTB7 polymer. The transfer time is estimated to be ca. 70 ps in PTB7-1L@MoS2, while it is significantly accelerated to ca. 1 ps in PTB7-5L@MoS2. Finally, we have found that the electron transfer is mainly controlled by adiabatic electron evolution, whereas in the hole transfer, nonadiabatic hoppings play a dominant role. These findings are useful for the design of excellent charge-separated interfaces of mixed-dimensional TMD-based heterojunctions for a variety of optoelectronic applications.

Role of phosphate in ruthenium-complex-sensitized TiO2 system for hydrogen production: Mechanism and kinetics

Most Ru(II) complex-sensitized TiO2 systems for hydrogen (H2) production suffer from instability of the photosensitized system because the anchoring groups of Ru(II) dyes, which are required for their adsorption on TiO2, are intrinsically vulnerable to chemical and photochemical cleavage. In this study, a new method that enables the use of a Ru(II) dye without any anchoring groups (Ru(bpy)32+) was developed and investigated. The stable photocatalytic efficiency in repeated H2 production cycles under visible-light irradiation indicates that the Ru(II) dye without anchoring groups is highly stable during dye-sensitized H2 production. The dye-sensitized H2 production in the Ru(bpy)32+-sensitized TiO2 system comprising Ru(bpy)32+ as a photosensitizer, platinized TiO2 (Pt-TiO2) as a cocatalyst-electron mediator, and ethylenediaminetetraacetic acid as an electron donor was negligible. However, the addition of phosphate (PO43–) to the Ru(bpy)32+-sensitized TiO2 system enabled the production of H2 via dye sensitization in the absence of any anchoring groups on the dye. The adsorption of PO43– changed the surface charge of Pt-TiO2 from positive to negative under acidic conditions, thereby inducing adsorption of cationic Ru(bpy)32+ on the surface of Pt-TiO2 and facilitating electron transfer from excited Ru(bpy)32+ to the conduction band of TiO2. The PO43– adsorption-induced change in the surface charge and the subsequent adsorption of Ru(bpy)32+ on the surface of PO43–-adsorbed Pt-TiO2 were confirmed by zeta potential measurements and Fourier transform infrared spectroscopy, respectively. In contrast with H2 production, the presence of PO43– had little effect on the kinetics of anionic chromate (CrO42–) reduction in the Ru(bpy)32+-sensitized TiO2 system. This result indicates that electron transfer from Pt to the electron acceptor on PO43–-adsorbed Pt-TiO2 is highly dependent on the charge character of the electron acceptor (i.e., electron transfer to the cationic electron acceptor is more favored). The negative charge on the surface of Pt-TiO2 induced by the adsorption of PO43– attracts the positively charged protons to the surface, which kinetically enhanced electron transfer from Pt to the protons. The (photo)electrochemical data demonstrate that PO43– adsorbed on Pt-TiO2 facilitates the interfacial electron transfer processes by enhancing the adsorption of Ru(bpy)32+ and attracting protons to the surface. The positive effect of PO43– on H2 production increased with increasing PO43– concentration and decreasing pH, where the conditions are more favorable for PO43– and proton adsorption on the surface of Pt-TiO2. Among the five anions evaluated in this study (PO43–, AsO43–, F–, NO3–, and SO42–), PO43– was most efficient and facilitated stable H2 production.

Effects of Interfacial Electron Transfer in Metal Complex–Semiconductor Hybrid Photocatalysts on Z-Scheme CO2 Reduction under Visible Light

The Z-scheme CO2 reduction activity of metal complex–semiconductor hybrid photocatalysts was investigated in detail with a focus on the interfacial electron transfer process. Semiconductors of GaN:...

NIR-Light-Active ZnO-Based Nanohybrids for Bacterial Biofilm Treatment.

Nanomaterials with antimicrobial properties triggered by external stimuli appear to be a promising and innovative substitute for the destruction of antibiotic-resistant superbugs as they can induce multiple disruptions in the cellular mechanism. This study demonstrates the use of squaraine (SQ) dye as the photosensitive material, activated in the near-infrared tissue-transparent therapeutic window. The dye has been covalently attached to the ZnO nanoparticle surface, forming ZnO-SQ nanohybrids. The formation of the nanohybrids is confirmed using Fourier transform infrared and other optical spectroscopic methods. The photoinduced interfacial electron transfer process (as confirmed using the time-resolved fluorescence technique) from the excited state of SQ to the conduction band of ZnO is responsible for the greater reactive oxygen species (ROS) generation ability of the nanohybrid. The production of photoactivated ROS (especially singlet oxygen species) by ZnO-SQ provides remarkable antimicrobial action against clinically significant Staphylococcus aureus. Detailed investigations suggest synergistic involvement of cell membrane disruption and nanoparticle internalization followed by photoinduced intracellular ROS generation, which result in an unprecedented 95% bacterial killing activity by the nanohybrid. Moreover, the efficacy of the nanohybrid for disruption of bacterial biofilms has been examined. The electron microscopic images suggest significant bacterial cell death following structural alteration and reduced adherence property of the biofilms. Nanodimension-driven greater internalization of ZnO-SQ followed by an improved dissolution of ZnO in an acidic environment of the biofilm as well as red-light-driven interfacial charge separation and ROS generation improves the efficacy of the material for biofilm destruction. An artificial medical implant mimicking titanium sheets coated with ZnO-SQ depicts light-triggered disruption in the adherence property of matured biofilms. The cytotoxicity and hemolysis assays show inherent biocompatibility of the photoactive nanohybrid. This study is notably promising for the treatment of life-threatening drug-resistant infections and eradication of biofilms formed within artificial implants.

Fabrication of platinum nitrogen-doped graphene nanocomposite modified electrode for the electrochemical detection of acetaminophen

An electrochemical sensor for the determination of acetaminophen (AC) was fabricated on glassy carbon electrode (GCE) modified with platinum nitrogen-doped graphene (Pt/NGr) nanocomposite. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square-wave voltammetry (SWV) were performed to investigate the electrochemical behaviour of AC. From the electrochemical results, the synergy between platinum nanoparticles and nitrogen-doped graphene improved the interfacial electron transfer process, thus exhibited a higher catalytic performance towards the electrochemical oxidation of AC. A linear range between 0.05–90 μmol L−1 for the determination of AC was achieved with a limit of detection of 0.008 μmol L−1. The prepared sensor demonstrated acceptable reproducibility, stability and good selectivity in the presence of interferences such as ascorbic acid, p-aminophenol and dopamine. In addition, this method showed satisfactory results in commercial tablets.

Comparison of Interfacial Electron Transfer Efficiency in [Fe(ctpy)2]2+-TiO2 and [Fe(cCNC)2]2+-TiO2 Assemblies: Importance of Conformational Sampling.

Fe(II)-polypyridines have limited applications as chromophores in dye-sensitized solar cells due to the short lifetimes (∼100 fs) of their photoactive metal-to-ligand charge transfer (MLCT) states formed upon photoexcitation. Recently, a 100-fold increase in the MLCT lifetime was observed in a [Fe(CNC)2]2+ complex (CNC = 2,6-bis(3-methylimidazole-1-ylidine)pyridine) which has strong σ-donating N-heterocyclic carbene ligand in comparison to the weaker field parent [Fe(tpy)2]2+ complex (tpy = 2,2':6',2″-terpyridine). This study utilizes density functional theory (DFT), time-dependent DFT, and quantum dynamics simulations to investigate the interfacial electron transfer (IET) in [Fe(cCNC)2]2+ (cCNC = 4'-carboxy-2,6-bis(3-methylimidazole-1-ylidine)pyridine) and [Fe(ctpy)2]2+ (ctpy = 4'-carboxy-2,2':6',2″-terpyridine) sensitized TiO2. Our results suggest that the replacement of tpy by CNC ligand does not significantly speed up the IET kinetics in the [Fe(cCNC)2]2+-TiO2 assembly in comparison to the [Fe(ctpy)2]2+-TiO2 analogue. The high IET efficiency in the [Fe(cCNC)2]2+-TiO2 assemblies is therefore due to longer lifetime of [Fe(cCNC)2]2+ photoactive 3MLCT states rather than faster electron injection kinetics. It was also found that the inclusion of conformational sampling in the computational model is important for proper description of the IET processes in these systems, as the models relying on the use of only fully optimized structures may yield misleading results. The simulations presented in this work also illustrate various pitfalls of utilizing properties such as electronic coupling, number of available acceptor states, and driving force, as well as calculations based on Fermi's golden rule framework, to reach conclusions on the IET efficiency in dye-semiconductor systems.

Organic cation steered interfacial electron transfer within organic–inorganic perovskite solar cells

The proton proximity arising from methylamine (MA) at TiO2/MAPbI3interface plays a vital role in facilitating interfacial electron transfer process

Tailoring of pore structure in mesoporous carbon for favourable flavin mediated interfacial electron transfer in microbial fuel cells.

Mesoporous carbon (MC) is supposed to be a good candidate for microbial fuel cell (MFC) anodes as it possesses a large specific area for the redox reaction of the electron shuttles and should deliver high power density. However, the power generation performance of MC anodes is often un-satisfying. It seems that a large portion of the pore surface is not available for anodic redox reaction but the reason is not clear. Here, three MCs with different pore sizes and pore shapes were fabricated and used to explore the effect of the pore structure on the bioelectrocatalysis in Shewanella putrefaciens CN32 MFCs. It is interesting that MC with 40–60 nm spheric pores (MC-III) possesses superior bio-electrocatalytic performance to the CMK-3 (MC-I with 3 nm channel like pores) and the one with 14 nm spheric pores (MC-II) although the specific surface area of MC-III is lower than MC-II and MC-I. The reason might be that the MC-III provides a more favorable pore structure than the other two MCs for flavin based redox reaction at the interface between the biofilm and the electrode. As a result, the MC-III anode delivered the highest power density at around 1700 mW m−2, which is 1.6 fold higher than that of the MC-I anode. A possible mechanism for the pore shape/size dependent interfacial electron transfer process has also been proposed. This work reveals that spheric mesopores with large pore width could be more favorable than the narrow channel-like pores for flavin based interfacial electron transfer in biofilm anodes, which will provide some insights for the design of the mesoporous anode in MFCs.

Photoinduced Interfacial Electron Transfer in 2,2’‐Bipyridyl Iron(III) Complex‐TiO2 Nanoparticles in Aqueous Medium

AbstractThe near‐UV and visible light induced interfacial electron transfer (IFET) process between aqueous solution of [Fe(bipy)2Cl2][FeCl4] complex and TiO2 NPs has been proved at first time and the photochemical products were mainly characterized by electronic absorption, Fe K‐edge X‐ray absorption fine structure, electron paramagnetic resonance and 57Fe Mössbauer spectroscopic method. This study makes in comprehending for the combination of semiconductor NPs and metal complex, in‐particularly ionic salt like complex has potential in environmental friendly synthesis and remediation process.

Kinetics analysis of interfacial electron-transfer processes in goethite suspensions systems

The photochemical behavior of goethite has been one of the most important topics in the field of environmental science due to it plays a significant role in the removal and transformation process of numerous pollutants. However, the interfacial electron transfer process of goethite is not clear. Using a nanosecond laser flash photolysis spectrometer, we report the transient spectroscopic observations of interfacial electron-transfer reactions in goethite dispersion under UV irradiation. Excitation of goethite generated conduction-band electron (ecb−) and hole (h+). The conduction band electron (ecb−) reacted with an electron acceptor, methylviologen dichloride hydrate (MV2+), forming reduced methylviologen (MV+) with a second-order rate constant of (2.6 ± 0.3) × 109 L mol−1 s−1. The concentration of MV+ was strongly influenced by MV2+ initial concentration and pH values. The flat band potential of goethite was calculated to be Efb (goethite, pH = 7) = 0.24 V (vs NHE). Oxygen did not react with conduction band electron of goethite. The present study provides a reliable method to investigate the photo-induced interfacial charge transfer of goethite.

Self-Assembling PDDA on Graphene to Surfactant-Free Synthesize Uniform and Ultra-Small Pd Nanocrystals by Direct CO Reduction for Efficient Catalyst Toward Formic Acid Oxidation

Herein a facile strategy to self-assemble PDDA on graphene for surfactant-free synthesizing uniform and ultra-small Pd nano-crystals (Pd@PDDA-G, average size of 3.4 nm) by direct CO reduction has been accomplished. The as-prepared Pd@PDDA-G catalyst exhibits much more negative half-wave potential than the commercial Pd/C and Pd@G without using PDDA by 40 mV and 15 mV as well as much higher peak current density than latters by 2.5 and 2 times, respectively toward formic acid oxidation, demonstrating superior electrocatalytic activity. In addition, the catalyst presents better stability than both Pd@G and commercial Pd/C. The electrocatalytic enhancement mechanism could be attributed to produced uniformly ultra-small and clean Pd nanocrystals on porous graphene for high reaction surface area and fast interfacial electron transfer process. This work also offers a universal route to prepare other high performance catalysts for broad applications in energy systems and sensing devices.

Highly sensitive, atmospheric pressure operatable sensor based on Au nanoclusters decorated TiO2@Au heterojunction nanorods for trace level NO2 gas detection

A controlled synthetic strategy is established for the development of TiO2@Au heterojunction nanorods using a facile wet-chemical method for the detection of NO2 gas under atmospheric pressure conditions. Structural studies reveal the existence of metastable anatase phase along with thermodynamically stable rutile phase with high degree of crystallinity. The structural analysis divulges the uniform surface anchoring of Au nanoclusters onto mono-dispersed TiO2 nanorods introducing interfacial metal–semiconductor heterojunctions. TiO2@Au heterojunction nanorods exhibited excellent sensor performance towards trace level exposure of NO2 gas. Owing to the interfacial electron transfer process at the heterojunction the optimum operating temperature of TiO2@Au heterojunction nanorods determined to be 250 °C, which is much less as compared to pristine TiO2 gas sensors (400 °C). Sensor response was found to be linear for the trace level concentration range of 0.5–5 ppm with lowest detection limit as 500 ppb. The TiO2@Au heterojunction nanorods exhibited higher sensitivity at atmospheric pressure conditions compared to vacuum conditions because of the changes in surface O2 adsorption properties of the heterojunction material at different oxygen partial pressure and existence of mixed phases in TiO2 nanorods. The superior gas sensor performance of the material under atmospheric pressure conditions point towards their potential for real-time applications.

Silicate sol–gel matrix stabilized ZnO–Ag nanocomposites materials and their environmental remediation applications

A facile preparation method was employed to decorate the zinc oxide nanoparticles by aminosilicate sol-gel supported silver nanoparticles (TPDT/(ZnO-Ag) NCMs). The nanocomposite photocatalyst materials were characterized by UV–vis absorption spectra, DRS, XRD, SEM and EDX techniques. The absorption spectral studies showed that the Ag nanoparticles (Ag NPs) were deposited on the ZnO nanoparticles (ZnO NPs) (represented as TPDT/(ZnO-Ag) NCMs) and the NCMs are highly stable. The photocatalytic oxidation and reduction reactions at the TPDT/(ZnO-Ag) NCMs photocatalysts were evaluated by using the toxic methylene blue (MB) dye and hexavalent chromium (Cr(VI)), respectively under visible light irradiation. The photocatalytic activity of the NCMs showed that the MB dye was completely decolorized at TPDT/(ZnO-Ag) 0.1 NCMs photocatalyst when compared to the controlled photocatalyst materials. The photocatalytic reduction of highly toxic Cr(VI) to less toxic Cr(III) was studied at the photocatalyst TPDT/(ZnO-Ag) 0.5 NCMs in the presence of hole scavengers such as oxalic acid. The Ag NPs deposited on the ZnO NPs and dispersed in silicate sol-gel matrix (TPDT/(ZnO-Ag) NCMs) improved the photocatalytic activity of the ZnO NPs photocatalyst with effective interfacial electron transfer processes at the ZnO by minimizing the charge recombination process when compared to the bare ZnO NPs. The TPDT/(ZnO-Ag) NCMs showed promising environmental remediation and water purification processes through the synergistic photocatalytic activity by advanced oxidation-reduction processes.

Impact of Local Electric Fields on Charge-Transfer Processes at the TiO2/Dye/Electrolyte Interface

Photoinduced electron-transfer processes at the TiO2/dye/electrolyte interface are vital for various emerging technologies. Here, the impact of the local electric field at this interface on the charge-transfer processes was investigated in two aspects: (a) charge recombination between the electrons accumulated within TiO2 and the photoxidized dye and (b) regeneration of the dyes by the cobalt bipyridyl redox mediators. The amplitude of the local electric field was changed by use of different cations in the electrolytic environment, in the order ECa2+ > EMg2+ > ENa+ > ELi+ characterized by the transient absorption spectroscopy. For the charge recombination process, the kinetic time constant showed a remarkable linear correlation with the relative electric field strength, while for the regeneration process, no evident dependence was observed. These results collectively suggest the spatial confinement of the effects of the local electric field on the interfacial electron-transfer processes.

Bimetallic Nanocomposites of Palladium (100) and Ruthenium for Electrooxidation of Ammonia

Symmmetrically oriented Pd (100) and its bimetallic Pd (100)Ru electrocatalysts were chemically synthesized and their conductive properties employed in the electrochemical oxidation of ammonia. Electrochemical data based on EIS, SWV and CV revealed that the Pt/Pd (100)Ru electrode showed a better conductivity and higher catalytic response towards the electrooxidation of ammonia compared to Pt/Pd (100) electrode. This was demonstrated by the EIS results where Pt/Pd (100)Ru gave a charge transfer resistance (Rct) of 48.64 Ω, high exchange current and lower time constant (5.2738 x 10-1A and 3.2802 x 10-7 s /rad) values while the Pt/Pd (100) had values of 173.2 Ω, 1.4811 x 10-1A and 4.8321 10-7 s /rad. The drastic drop in Rct highlights the superiority of the Pt/Pd (100)Ru over the Pt/Pd (100) and confirms that facile interfacial electron transfer processes occur on the Pt/Pd (100)Ru electrode during the electrocatalytic ammonia oxidation. Investigations through voltammetry revealed that the Pt/Pd (100)Ru had a higher peak current density and a shift in potential to more negative values at ≈ -0.2 V and ≈ -0.4 V. The EASA value of Pt/Pd (100)Ru was found to be 119.24 cm2 whereas Pt/Pd (100) had value of 75.07 cm2. The high electrochemically active surface area of Pd (100)Ru at 119.24 cm2 compared to the 75.07 cm2 for Pd (100) strengthened this observation in performance between the two catalysts for ammonia electrooxidation.

Charge transfer-resistance in nitrogen-doped/undoped graphene: Its influence on the electro-catalytic reduction of H2O2

Nitrogen doped (N-Gr) and undoped (TRGO) graphene were chemically synthesized and characterized by TEM, STEM-EDX and XPS. The electrochemical reduction of H2O2 was investigated with bare glassy carbon (GC) electrode and with GC modified with each graphene sample. The active area of TRGO/GC and N-Gr/GC modified electrodes were found to be 0.75 and 0.295cm2, respectively. Both were considerably larger than that of bare GC (0.07cm2). We carefully looked at the kinetic of interfacial electron transfer process and found that the charge-transfer resistance (Rct) of TRGO/GC electrode (7.83×106 Ω) was significantly lower than that of N-Gr/GC electrode (4.81×107 Ω) or bare GC (1.74×109 Ω). Interestingly, although TRGO/GC electrode had the largest active area and the smallest charge transfer resistance, it did not promote the H2O2 electrochemical reduction. In contrast, N-Gr/GC modified electrode exhibited an enhanced electro-catalytic activity towards H2O2 reduction, which was related to the presence of heterogeneous atoms into the sp2 carbon network.

New benzothiadiazole-based dyes incorporating dithieno[3,2-b:2′,3′-d]pyrrole (DTP) π-linker for dye-sensitized solar cells with different electrolytes

Abstract Benzothiadiazole (BTZ)-based dyes incorporating dithieno[3,2- b :2′,3′- d ]pyrrole (DTP) π-linker has been synthesized for fabricating efficient dye-sensitized solar cells (DSSCs). A reference dye with ethylenedioxythiophene (EDOT) π-linker has also been prepared. The introduction of DTP broadens absorption, provides a more planar skeleton, and reduces HOMO and LUMO energy gap. IMVS and EIS measurements are used to investigate interfacial electron transfer processes of device. Dyes incorporating DTP exhibit more effective inhibition of charge recombination and more conducive to electron injection than the reference dye with EDOT. Therefore, much higher efficiency is obtained in device fabricated by DTP-based dyes, and the best performance achieves a power conversion efficiency of 8.14% by using Co-phen based electrolyte. In contrast, device based on the reference dye reaches 5.22% at most. IPCE characterizations and the effect of Co-bpy and I − /I 3 − redox couple are also discussed. The DTP moiety is a good candidate for the design of BTZ-based sensitizers used in DSSCs.

Ternary nanohybrid of reduced graphene oxide-nafion@silver nanoparticles for boosting the sensor performance in non-enzymatic amperometric detection of hydrogen peroxide

A sensitive and novel electrochemical sensor was developed for the detection of hydrogen peroxide (H2O2) using a reduced graphene oxide-nafion@silver6 (rGO-Nf@Ag6) nanohybrid modified glassy carbon electrode (GC/rGO-Nf@Ag6). The GC/rGO-Nf@Ag6 electrode exhibited an excellent electrochemical sensing ability for determining H2O2 with high sensitivity and selectivity. The detection limit of the electrochemical sensor using the GC/rGO-Nf@Ag6 electrode for H2O2 determination was calculated to be 5.35×10−7M with sensitivity of 0.4508µAµM−1. The coupling between rGO-Nf with silver nanoparticles (AgNPs) significantly boosted the electroanalytical performance by providing more active area for analyte interaction, thereby allowing more rapid interfacial electron transfer process. The interfering effect on the current response of H2O2 was studied and the results revealed that the sensor electrode exhibited an excellent immunity from most common interferents. The proposed non-enzymatic electrochemical sensor was used for determining H2O2 in apple juice, and the sensor electrode provided satisfactory results with reliable recovery values. These studies revealed that the novel GC/rGO-Nf@Ag6 sensor electrode could be a potential candidate for the detection of H2O2.

Electronic Processes within Quantum Dot-Molecule Complexes.

The subject of this review is the colloidal quantum dot (QD) and specifically the interaction of the QD with proximate molecules. It covers various functions of these molecules, including (i) ligands for the QDs, coupled electronically or vibrationally to localized surface states or to the delocalized states of the QD core, (ii) energy or electron donors or acceptors for the QDs, and (iii) structural components of QD assemblies that dictate QD-QD or QD-molecule interactions. Research on interactions of ligands with colloidal QDs has revealed that ligands determine not only the excited state dynamics of the QD but also, in some cases, its ground state electronic structure. Specifically, the article discusses (i) measurement of the electronic structure of colloidal QDs and the influence of their surface chemistry, in particular, dipolar ligands and exciton-delocalizing ligands, on their electronic energies; (ii) the role of molecules in interfacial electron and energy transfer processes involving QDs, including electron-to-vibrational energy transfer and the use of the ligand shell of a QD as a semipermeable membrane that gates its redox activity; and (iii) a particular application of colloidal QDs, photoredox catalysis, which exploits the combination of the electronic structure of the QD core and the chemistry at its surface to use the energy of the QD excited state to drive chemical reactions.