Electron Transfer Properties Research Articles

Revival of Insulating Polyethylenimine by Creatively Carbonizing with Perylene into Highly Crystallized Carbon Dots as the Cathode Interlayer for High-Performance Organic Solar Cells.

The development of new electron transporting layer (ETL) materials to improve the charge carrier extraction and collection ability between cathode and the active layer has been demonstrated to be an effective approach to enhance the photovoltaic performance of organic solar cells (OSCs). Herein, water-soluble carbon dots (CDs) as ETL material have been creatively synthesized by a vigorous chemical reaction between polyethylenimine (PEI) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) via a simple one-step hydrothermal method. Taking full advantage of the high electron transfer property of PTCDA and the work function (WF) reduction ability of PEI, CD gained high electron mobility due to its large π-conjugated area and reduced the WF of indium tin oxide (ITO) by 0.75 eV. As for the photovoltaic performance of devices, inverted OSCs based on CDs have achieved a high power conversion efficiency (PCE) of 17.35%, exhibiting no burn-in effect with no reduction in PCE after more than 4000 h of storage. The successful application of CDs in OPV has developed a new avenue for designing efficient ETL materials that benefits the photovoltaic performance of OSCs.

Simple method for making MWCNTs/Au-NPs-based biosensor electrodes

Multiwalled carbon nanotubes have great potential when applied as biosensors. Their properties, especially as electrodes with electrochemical characteristics, offer strong benefits for developing biosensors. This research has been able to integrate multiwalled carbon nanotubes (MWCNTs) with Au nanoparticles (Au-NPs) to obtain several new superior properties. Cysteaminium chloride is used to link MWCNTs and Au-NPs while binding to specific antibodies to make them more sensitive to some diseases or viruses. The data on the success of the bonding of MWCNTs/Au-NPs were tested using three characterizations, namely FTIR, SEM, and XRD. Based on the results of testing electrochemical properties using the CV and EIS tests, the capacitance value of 6,363 Fg−1 and the Rct value of 717,9 Ω, respectively. This demonstrates good adhesion and electron transfer properties from the electrolyte to the probe and electrode.

Quantum Chemical Analysis of Global and Local Electron Transfer Properties of Dihydroxy Benzenes for Accessing Their Antioxidant Activity with Experimental Shreds of Evidence

Quantum Chemical Analysis of Global and Local Electron Transfer Properties of Dihydroxy Benzenes for Accessing Their Antioxidant Activity with Experimental Shreds of Evidence

Investigation of the electron transfer properties between metal centers in binuclear and trinuclear cyanido-bridged mixed valence complexes with cis/trans-configuration.

To investigate the electron transfer properties between metal centers and their influencing factors in binuclear and trinuclear cyanido-bridged mixed valence complexes with cis/trans-configuration, binuclear cis-[Cp(dppe)Fe(μ-NC)Ru(5,5'-dmbpy)2(μ-CN)][PF6]n (cis-1[PF6]n, n = 1, 2) and trinuclear cis/trans-[Cp(dppe)Fe(μ-NC)Ru(5,5'-dmbpy)2(μ-CN)Fe(dppe)Cp][PF6]n (cis/trans-2[PF6]n, n = 2, 3, 4) (Cp = 1,3-cyclopentadiene, dppe = 1,2-bis(diphenylphosphino)ethane, 5,5'-dmbpy = 5,5'-dimethyl-2,2'-bipyridyl) cyanido-bridged complexes were synthesized and well characterized. The experimental results indicate that the presence of the other terminal fragment Cp(dppe)FeIII in cis-2[PF6]4 results in higher MMCT energy than that of cis-1[PF6]2. In addition, the trans-configuration is more conducive to electron transfer between metal centers than the cis-configuration in trinuclear cyanido-bridged mixed valence complexes. Moreover, these mixed valence complexes cis-1[PF6]2 and cis/trans-2[PF6]n (n = 3, 4) could be assigned to Class II systems according to Robin and Day.

Improved visible light-driven photocatalytic degradation of methylene blue and methyl red by boron-doped carbon quantum dots.

The synthesis of fluorescent carbon quantum dots (CQDs) and their applications have attracted great attention due to their excellent properties. Especially, the unique visible-light absorption and photo-induced electron transfer properties make CQDs available in photocatalytic degradation of organic dye pollutants in water resources. Herein, we synthesized nondoped CQDs and boron-doped CQDs (B-CQDs) by hydrothermal method and compared their photocatalytic degradation activity of methylene blue (MB) and methyl red (MR) dyes under visible light irradiation. The characterization outcomes showed that the optical and structural properties can be easily improved by doping with hetero-atom, thereby photocatalytic performance. As expected, the photodegradation performance of both organic dyes in model solutions by B-CQDs was higher than that of CQDs. MB and MR dyes were photodegraded over 95% by B-CQDs in 90 and 120 min visible light irradiation, respectively. Eventually, the results revealed that nondoped CQDs and B-CQDs are excellent candidates for the degradation of organic dyes because of their high photocatalytic performance under visible light illumination.

Transient potentiometry based d-serine sensor using engineered d-amino acid oxidase showing quasi-direct electron transfer property

d-Serine biosensing has been extensively reported based on enzyme sensors using flavin adenine dinucleotide (FAD) -dependent d-amino acid oxidase (DAAOx), based on the monitoring of hydrogen peroxide generated by the enzymatic reaction, which is affected by dissolved oxygen concentration in the measurement environment in in vivo use. Here we report a novel sensing principle for d-serine, transient potentiometry based d-serine sensor using engineered DAAOx showing quasi-direct electron transfer (DET) property. DAAOx Gly52Val mutant, revealed to possess dye-mediated dehydrogenase activity using artificial synthetic electron acceptors, while its oxidase activity was negligible. The enzyme was immobilized on electrode and was modified with amine-reactive phenazine ethosulfate, resulted an enzyme electrode showing quasi-DET type response. Although OCP based monitoring took more than several minutes to obtain steady state OCP value, the time dependent OCP change monitoring, transient potentiometry, provided rapid and sensitive sensor signals. While dOCP/dt based monitoring was suitable for sensing with longer than 5 s time resolution with d-serine concentration range between 0.5 mM and 5 mM, dOCP/d t based monitoring is suitable for d-serine monitoring with much shorter time resolution (less than 1 s) with high sensitivity with wider dynamic range (20 μM–30 mM). The maximum dOCP/d t was −39.2 ± 2.0 mV/s1/2, the Km(app) was 1.9 mM, and the lower limit of detection was 20 μM. In addition, d-serine monitoring was also possible in the artificial cerebrospinal fluid. The transient potentiometry based sensing reported in this study will be further utilized to realize miniaturized, continuous, real-time, in vivo sensor for d-serine monitoring.

Pre-post redox electron transfer regioselectivity at the alanine modified nano graphene electrode interface

Alanine (AL) has been used as a electrode modifier to alter the carbon paste interface for sensing applications. Unfortunately, still, electron transfer (ET) properties of AL modified graphene (GR) interface are not known. Density Functional Theory (DFT) based GR interface will help to know the molecular view of interface. In the current article AL modified GR interface modeled using DFT-based frontier molecular orbital (FMO) theory and analytical Fukui functions. At the AL modified GR interface, the N atom of AL acts like an additional electron donor site, and a carboxylic acid, methyl, and amine group act like a reduction center.

Neodymium (3+)‐Coordinated Black Phosphorus Quantum Dots with Retrievable NIR/X‐Ray Optoelectronic Switching Effect for Anti‐Glioblastoma

Heteroatom interaction of atomically thin nanomaterials enables the improvement of electronic transfer, band structure, and optical properties. Black phosphorus quantum dots (BP QDs) are considered to be candidate diagnostic and/or therapeutic agents due to their innate biocompatibility and exceptional photochemical effects. However, BP QDs are not competitive regarding second near-infrared (NIR-II) window medical diagnosis and X-ray induced phototherapy. Here, an Nd3+ ion coordinated BP QD (BPNd) is synthesized with the aim to sufficiently improve its performances in NIR-II fluorescence imaging and X-ray induced photodynamic therapy, benefitting from the retrievable NIR/X-ray optoelectronic switching effects between BP QD and Nd3+ ion. Given its ultrasmall size and efficient cargo loading capacity, BPNd can easily cross the blood-brain barrier to precisely monitor the growth of glioblastoma through intracranial NIR-II fluorescence imaging and impede its progression by specific X-ray induced, synergistic photodynamic chemotherapy.

Effective enhancement of electron migration and photocatalytic performance of nitrogen-rich carbon nitride by constructing fungal carbon dot/molybdenum disulfide cocatalytic system

To find a cocatalyst that can replace noble metals, fungal carbon dot (CD) modified molybdenum disulfide (MoS2) cocatalyst system was designed. The composites were prepared by hydrothermal and calcination methods with different ratios of CDs, MoS2 and nitrogen-rich carbon nitride (p-C3N5). p-C3N5 has excellent electronic properties, and MoS2 modified by CDs (D-MoS2) can significantly enhance the photocatalytic performance of p-C3N5 by improving the photogenerated electron migration efficiency. The experiments showed that the developed CDs/MoS2/C3N5 composites exhibited excellent performance in both photocatalytic hydrogen (H2) evolution and methylene blue (MB) degradation, with CMSCN5 (D-MoS2 with 5% mass fraction) showing the best photocatalytic activity. The corresponding H2 evolution rate of CMSCN5 was 444 μmol g-1h−1 and 1.45 times higher than that of unmodified p-C3N5, by 120 min, the removal rate of MB was up to 93.51%. The 5 cycle tests showed that CMSCN5 had great stability. The high charge mobility and high density of H2 evolution active sites of MoS2 nanosheets, together with the electron storage and transfer properties of CDs can obviously improve electron migration and reduce the photogenerated carrier recombination on the p-C3N5 surface. The design and preparation of such composites offer broad prospects for the development of photocatalytic systems with noble metal-free cocatalysts.

Photolithographic 3D microarray electrode-based high-performance non-enzymatic H2O2 sensor

In recent years, electrochemical biosensors have been widely used in health care, and, due to the increasing demand for their use, new sensing performance requirements have been proposed. Widening detection range and speeding up response rate while improving the sensitivity of these sensors is a major current challenge. In this study, a high-performance three-dimensional (3D) non-enzymatic hydrogen peroxide biosensor was fabricated based on a simple photolithographic process. Neatly arranged cylindrical microarrays (MA) with clear edges were fabricated using SU-8 photoresist. Subsequently, a gold thin film was sputtered onto the MA to form a 3D Au/microarray electrode (Au/MAE). Additionally, we investigated the optimal size of the MA (aspect ratio = 2, diameter = 30 µm) required to obtain an Au/MAE with the best electron transfer properties. Based on these results, a 3D CuNPs/Au/MAE sensor was constructed via the electrochemical in-situ reduction of copper nanoparticles (CuNPs). Due to its increased specific surface area and contact sites, this 3D sensor with high stability and good selectivity for detecting hydrogen peroxide exhibited higher sensitivity and wider range of detection than 2D CuNPs/AuE sensor. Consequently, the design of 3D microarray structure provides a new strategy for the fabrication of high-performance sensors that can be used in clinical applications.

Photoinduced electron transfer properties of 4-phenyl-Pyridine-N-Oxide and its coordination compound

Photoinduced electron transfer (PET) with the formation of stable radicals plays an importance role in many areas. However, the discovery of new photoresponsive moieties is still a challenge. In this work, pyridine N-oxide group itself was demonstrated to possess photoinduced electron transfer (PET) property for the first time. The radical of 4-phenyl-pyridine-N-oxide (ppno), generated by PET from oxygen atom to 4-phenyl-pyridine part, remained stable in dark in air at least for two weeks. [ZnCl2(ppno)2], one ppno-based novel crystalline coordination compound, has two electron donors, chlorine and oxygen atoms. In particular, experimental and theoretical calculation results showed that oxygen atoms in [ZnCl2(ppno)2] have dual actions. Firstly, oxygen atom as electron-withdrawing group increased the electron accepting ability of 4-phenyl-pyridine. Then, oxygen atoms themselves are rich in electrons and can act as electron donors. This is exactly why the performance of PET and radical yield and stability of [ZnCl2(ppno)2] much better than ppno. Thus, pyridine N-oxide group as an effective photoresponsive functional motif, whether by interspersion or by coordination, could construct various novel photoresponsive materials.

Peptide sequence-driven direct electron transfer properties and binding behaviors of gold-binding peptide-fused glucose dehydrogenase on electrode

SummaryOriented enzyme immobilization on electrodes is crucial for interfacial electrical coupling of direct electron transfer (DET)-based enzyme-electrode systems. As inorganic-binding peptides are introduced as molecular binders and enzyme-orienting agents, inorganic-binding peptide-fused enzymes should be designed and constructed to achieve efficient DET. In this study, it is aimed to compare the effects of various gold-binding peptides (GBPs) fused to enzymes on electrocatalytic activity, bioactivity, and material-binding behaviors. Here, GBPs with identical gold-binding properties but different amino acid sequences were fused to the FAD-dependent glucose dehydrogenase gamma-alpha complex (GDHγα) to generate four GDHγα variants. The structural, biochemical, mechanical, and bioelectrochemical properties of these GDHγα variants immobilized on electrode were determined by their fused GBPs. Our results confirmed that the GBP type is vital in the design, construction, and optimization of GBP-fused enzyme-modified electrodes for facile interfacial DET and practical DET-based enzyme-electrode systems.

Does Location of BF2-Chelated Dipyrromethene (BODIPY) Ring Functionalization Affect Spectral and Electron Transfer Properties? Studies on α-, β-, and Meso-Functionalized BODIPY-Derived Donor–Acceptor Dyads and Triads

Does Location of BF₂-Chelated Dipyrromethene (BODIPY) Ring Functionalization Affect Spectral and Electron Transfer Properties? Studies on α-, β-, and Meso-Functionalized BODIPY-Derived Donor–Acceptor Dyads and Triads

Conductive Geopolymers as Low-Cost Electrode Materials for Microbial Fuel Cells.

Geopolymer (GP) inorganic binders have a superior acid resistance compared to conventional cement (e.g., Portland cement, PC) binders, have better microbial compatibility, and are suitable for introducing electrically conductive additives to improve electron and ion transfer properties. In this study, GP–graphite (GPG) composites and PC–graphite (PCG) composites with a graphite content of 1–10 vol % were prepared and characterized. The electrical conductivity percolation threshold of the GPG and PCG composites was around 7 and 8 vol %, respectively. GPG and PCG composites with a graphite content of 8 to 10 vol % were selected as anode electrodes for the electrochemical analysis in two-chamber polarized microbial fuel cells (MFCs). Graphite electrodes were used as the positive control reference material. Geobacter sulfurreducens was used as a biofilm-forming and electroactive model organism for MFC experiments. Compared to the conventional graphite anodes, the anode-respiring biofilms resulted in equal current production on GPG composite anodes, whereas the PCG composites showed a very poor performance. The largest mean value of the measured current densities of a GPG composite used as anodes in MFCs was 380.4 μA cm–2 with a standard deviation of 129.5 μA cm–2. Overall, the best results were obtained with electrodes having a relatively low Ohmic resistance, that is, GPG composites and graphite. The very first approach employing sustainable GPs as a low-cost electrode binder material in an MFC showed promising results with the potential to greatly reduce the production costs of MFCs, which would also increase the feasibility of MFC large-scale applications.

Electrochemical characterization of mutant forms of rubredoxin B from Mycobacterium tuberculosis

Electron transfer in metalloproteins is a driving force for many biological processes and widely distributed in nature. Rubredoxin B (RubB) from Mycobacterium tuberculosis is a first example among [1Fe-0S] proteins that support catalytic activity of terminal sterol-monooxygenases enabling its application in metabolic engineering. To explore the tolerance of RubB to the specific amino acid changes we evaluated the effect of surface mutations on its electrochemical properties. Based on the RubB fold we also designed the mutant with a putative additional site for protein-protein interactions to further evaluate electron transfer and electrochemical properties. The investigation of redox properties of mutant variants of RubB was done using screen-printed graphite electrodes (SPEs) modified with stable dispersion of multi-walled carbon nanotubes (MWCNTs). The redox potentials (midpoint potentials, E0Ꞌ) of mutants did not significantly differ from the wild type protein and vary in the range of −264 to −231 mV vs. Ag/AgCl electrode. However, all mutations affect electron transfer rate between the protein and electrode. Notably, the modulation of the protein-protein interactions was observed for the insertion mutant suggesting the possibility of tailoring of rubredoxin for the selected redox-partner. Overall, RubB is tolerant to the significant modifications in its structure enabling rational engineering of novel redox proteins.

Application of Functionalized Graphene Oxide Based Biosensors for Health Monitoring: Simple Graphene Derivatives to 3D Printed Platforms.

Biosensors hold great potential for revolutionizing personalized medicine and environmental monitoring. Their construction is the key factor which depends on either manufacturing techniques or robust sensing materials to improve efficacy of the device. Functional graphene is an attractive choice for transducing material due to its various advantages in interfacing with biorecognition elements. Graphene and its derivatives such as graphene oxide (GO) are thus being used extensively for biosensors for monitoring of diseases. In addition, graphene can be patterned to a variety of structures and is incorporated into biosensor devices such as microfluidic devices and electrochemical and plasmonic sensors. Among biosensing materials, GO is gaining much attention due to its easy synthesis process and patternable features, high functionality, and high electron transfer properties with a large surface area leading to sensitive point-of-use applications. Considering demand and recent challenges, this perspective review is an attempt to describe state-of-the-art biosensors based on functional graphene. Special emphasis is given to elucidating the mechanism of sensing while discussing different applications. Further, we describe the future prospects of functional GO-based biosensors for health care and environmental monitoring with a focus on additive manufacturing such as 3D printing.

Insights on the role of supporting electrospun carbon nanofibers with binary metallic carbides for enhancing their capacitive deionization performance

Recent development in desalination technology can be progressed in terms of fabricated nanomaterials and operating parameters, as one among energy-storing systems including fuel cells, capacitors, batteries, and so on. Regarding the examined nanomaterials, embedded CoCr7C3 nanoparticles onto carbon nanofibers (CoCr7C3@CNFs) were prepared using a facile electrospinning technique. Characterization techniques, such as XRD, FESEM, TEM, HRTEM, STEM, and EDX, were served to define the crystallinity, morphology and chemical composition of the synthesized nanofibers. XRD chart demonstrated the formation of Cr7C3 species along with deposited metallic cobalt in this nanomaterial. The morphological study revealed the uniform distribution of metallic cobalt and Cr7C3 nanoparticles onto the fibrous CNFs structure. The electrochemical performance of CoCr7C3@CNFs was studied in 1.0 M NaCl solution at 5 mV s−1 to record a specific capacitance of 250 F g−1. Electrochemical impedance spectroscopy measurements indicated better electron transfer properties after introducing CoCr7C3 to the CNFs structure. Furthermore, its outstanding electrosorption capacity of 20.40 mg g−1 might encourage the preparation of additional nanocomposites for future capacitive deionization (CDI) technology.

Synthesis and daylight photocatalytic properties of graphene/self-doped tin oxide/silver ternary nanocomposite on fabric surface

Visible light activity is a key point to improve the efficiency and practical application of photocatalytic process by using daylight irradiation. This work describes a novel method to produce an efficient rGO-Sn2+doped-SnO2-Ag ternary nanocomposite on polyethylene terephthalate (PET) fabric via the in-situ low-temperature redox reactions method. The structural characteristics of the produced nanocomposites were studied via UV–vis, XRD, Raman, FTIR, XPS, PL, FESEM and EDX techniques. The observed results indicated that a well-controlled SnO2 nanostructure with different morphologies (nanoparticles, nanosheets, and nanorods) was synthesized on the fabric surface. The photocatalytic activity was evaluated by the degradation of methylene blue (MB) under daylight irradiation. In particular, the photocatalytic properties of Sn2+:SnO2 enhances in presence of rGO and Ag under daylight as shown in optical bandgaps measurement and dye photodegradation. Among the samples, the photocatalytic activity of sample with 10% Ag is most satisfactory as it has great optical and electron transfer properties on nanocomposites. The results of the research could facilitate the production of an efficient and stable visible photocatalyst nanostructure.

Photoinduced Generation of Metastable Sulfur Vacancies Enhancing the Intrinsic Hydrogen Evolution Behavior of Semiconductors

Hydrogen evolution over pristine semiconductors is desirable but seldom realized in powdered photocatalysis. It requires the catalyst surface simultaneously possessing efficient electron transfer and rapid H2 production properties. The current semiconductor photocatalysts have to depend on additional cocatalysts to achieve the H2 evolution process. Herein, theoretical and experimental results demonstrate that metastable sulfur vacancy could significantly enhance the intrinsic H2 evolution behavior of semiconductors. The hydrogen adsorption free energy (ΔGH) of CdS could be optimized to ΔGH = 0.01 eV, much lower than that over thermodynamically stable vacancies (ΔGH = 0.31 eV). The experiment is conducted based on kinds of supported CdS nanoparticles prepared with the anion‐exchange method. A series of in situ characterizations disclose that a metastable sulfur vacancy forms under photoexcitation and is stable during the reaction. These metastable sulfur vacancies cause the formation of intermediate states between the valence band and the conduction band that increase transportation and utilization of photogenerated electrons. The conceptual finding of the critical role of the metastable vacancy in enhancing H2 evolution would bring new thinking on the design of semiconductor photocatalysts to be less dependent on cocatalysts.

Theoretical study on pentiptycene molecular brake: photoinduced isomerization and photoinduced electron transfer.

The isomerization of the double bond plays an important role in the braking and de-braking of the light-controlled molecular brake. Therefore, the pentiptycene-type (Pp-type) light-controlled molecular brake system ((E)- and (Z)-4'-pentiptycyl vinyl-[1,1'-biphenyl]-4-carbonitrile) containing the C = C double bond was theoretically studied. Combining the 6-31G(d) basis set, the ωB97XD functional with dispersion correction was applied to implement the (E)-configuration and (Z)-configuration initial optimization. Next, using the 6-311G(d,p) basis set, the relaxed potential energy surface scans of the rotation angle were operated, and then the optimization calculations of the transition states at the extremum high points. Analyzing the stagnation points and the rotational transition states on the potential energy profiles, the rotation mechanism and basic energy parameters of the molecular brake were obtained. Then, the DFT computations at ground states and the TD-DFT computations of vertical excitation energy were put into practice at the accuracy of the def-TZVP basis set for the two configurations, and using the natural transition orbital (NTO) analyses combining the excitation energies and absorption spectra, the electronic transition characteristics and electron transfer properties of light-controlled molecular brake were studied. Afterwards, in order to investigate the photoinduced isomerization reaction, the C = C double bond was scanned on the relaxed potential energy surface, and the intermediates of the isomerization reaction were searched and analyzed; thus, the braking mechanism of the light-controlled molecular brake was proposed.