Transfer Carrier Research Articles

Engineering yolk-double-shell Au@CN@ZnIn2S4 architecture with enhanced photocatalytic properties.

The efficient utilization of light and the prolonged lifetime of photo-induced charge carriers are essential elements that contribute to superior photocatalytic activity. Yolk-shell nanostructures with porous shells and mobile cores offer significant structural advantages in achieving these goals. However, designing yolk-shell multicomponent nanocomposites with diverse architectures remains a persistent challenge. The present study involves the utilization of zinc indium sulfide (ZnIn2S4) flakes, which are uniformly incorporated into the yolk-shell Au@CN structure. The inclusion of ZnIn2S4 flakes in carbon nitride (CN) significantly enhances the performance of the overall system, allowing for efficient and rapid charge transfer. The uniform distribution of ZnIn2S4 flakes throughout the yolk-shell matrix ensures the catalytic activity is maximized, resulting in superior performance compared to conventional systems. The designed photocatalyst has a hollow interior which strengthens light absorption, a thin shell that shortens the electron migration distance, tight adhesion between shells, which makes it easier to separate and transfer carriers, and a movable Au core with localized surface plasmon resonance (LSPR) which can facilitate additional charge carrier generation for CN and ZnIn2S4. The yolk-shell microsphere composite of Au@CN@ZnIn2S4 shows a TC photodegradation rate of 72% within 2h, which is more than double the photodegradation rate of hollow CN and ZnIn2S4. The present study's experimental demonstrations valuable insights into the rational design of sophisticated metal-semiconductors double yolk-shell nanocrystals, particularly those composed of metal sulfides cocatalyst, for superior photocatalytic applications.

The catalytic role of Cr(VI) in promoting the degradation of organic pollutants via TiO2/SnO2/BiVO4 photoelectrocatalysis: As an electron transfer carrier.

Regarding the coexistence of heavy metals and organic pollutants, many studies have achieved synergistic removal of Cr(VI) and organic pollutants under acidic conditions. However, the role of Cr(VI) in the removal of organic pollutants under neutral conditions may have been overlooked. Here, the catalytic effect of Cr(VI) in promoting the photoelectrocatalytic degradation of organic pollutants was investigated using a ternary system, which was a combination of photocatalysis, electrocatalysis and Cr(VI) catalysis. A fabricated TiO2/SnO2/BiVO4 composite was used as an anode for degradation experiments. We found that the degradation efficiency and final removal of rhodamine B (RhB), ofloxacin (OFL), and tetracycline (TC) were improved by increasing the Cr(VI) concentration within the range of 10-20mgL-1. And the addition of Cr(VI) sharply improved the removal of the three organic pollutants under the optimal conditions (from 65% to 96% for RhB, from 34% to 81% for OFL, and from 43% to 100% for TC). According to the results of different processing methods and quenching experiments, we proposed a new catalytic mechanism that, Cr(VI) promotes PEC degradation by acting as an electron transfer carrier between TiO2/SnO2/BiVO4 and O2.

Flow microbubble emission boiling (MEB) in open microchannels for durable and efficient heat dissipation

Microbubble emission boiling (MEB) has been reported to be an advanced heat transfer mechanism due to its significant heat dissipation capacity at high heat flux. Microchannel heat sinks are considered to be effective heat transfer carriers, but MEB is difficult to be triggered in conventional microchannels due to insufficient mainflow subcooling and restriction of narrow channel walls. In this work, we conducted flow MEB experiments in plain and lasered open microchannels with various inlet temperatures (Tinlet) and open gap height (Hg). The open configuration can provide adequate mainflow subcooling and extra flow area to trigger MEB. The results showed that MEB occurred in plain open microchannels as a transition flow pattern between bubbly flow and flow reversal at Tinlet ≤ 25 °C and Hg = 0.3 mm, with a significant temperature drop after a one-time flow reversal, providing abundant vapor composition as MEB evaporation cores; MEB did not happen at higher Tinlet and larger Hg (1 mm). However, in lasered open microchannels, MEB was triggered at the beginning of flow boiling at Tinlet ≤ 65 °C with Hg = 0.3 and 1 mm, without temperature drop or flow reversal. This demonstrated that the required inlet subcooling, heat flux and temperature gradient in vertical direction for MEB initiation were simultaneously reduced in lasered microchannels. The two-phase heat transfer coefficient (htp) of MEB was significantly increased (up to 77.8 %) compared to conventional bubbly flow, due to the faster bubble nucleation frequency and rapid impact from the subcooled mainflow to channel walls, and was further enhanced in lasered microchannels. The durability of MEB in plain microchannel was unsatisfactory, as the persistent flow reversal dominated the flow pattern after ∼3750 s at G = 300 ml/min, Tinlet = 25 °C, Hg = 0.3 mm and qeff ∼1450 kW/m2. However, in lasered microchannels, MEB ran steadily for 22500 s at the same working condition. This study provided an effective and accessible method to achieve durable MEB in microchannels with excellent heat dissipation capacity, offering valuable insights for further thermal management engineering applications.

In situ construction of oriented Au/PPy nanorod arrays-based aptasensor for fast and ultrasensitive determination of thrombin

The dynamic changes in coagulation function indicators provide important references for early warning, disease progression, and prognosis evaluation of clinical cardio-cerebrovascular disease (CCVD) patients. However, current assay methods, such as enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay and colorimetry, are time-consuming, require bulky equipment, tedious operations, and long analytical period, which are difficult in achieving an on-site and rapid detection. To address above issues, we proposed an ultrasensitive and fast-responded aptasensor for the detection of a typical coagulation function indicator (Thrombin, Tob) through constructing a unique oriented Au/polypyrrole (PPy) nanorod arrays. This architecture has provided both high electrocatalysis and abundant active sites as the signal transfer and DNA carrier. Meanwhile, through the specific DNA-binding representative design, we also designed a target-induced chain release strategy based on the competitive interaction between Tob and cDNA, which remarkably accelerated the Tob recognition process. This aptasensor enables to present an ultralow detection limit of 3 fg/mL and fast detection time of 20 min in real human serum samples, together with the favorable repeatability, stability and anti-interference ability for early warning and prognosis prediction of CCVD. It is promising that this aptasensor can be extended to analyze more disease markers through the change of different bases sequence of the applied DNA stands, which will provide an on-site and convenient technique and device for clinical disease diagnosis.

Enhancing perovskite solar cells performance through tailored design: pyridine-functionalized phenothiazine derivatives with modified end-capped acceptor moieties

Abstract Future energy resources are being developed using clean and renewable energies since these sources offer environmentally friendly and sustainable choices to traditional sources like fossil fuels. Among various renewable energy sources, solar energy is becoming increasingly efficient with advancements in organic photovoltaic systems. Organic semiconductor materials, which require high electron affinity and possess desirable optical and electronic properties, are crucial for these systems. Researchers are constantly trying to increase the role of photovoltaic materials in optoelectronic applications. With current energy demands, there is a shift from traditional solar cells to perovskite photovoltaic materials due to their significant contributions to renewable energy. Therefore, we have designed a new stream of donor- π -acceptor (D- π -A) type pyridine functionalized phenothiazine derivates-based donor materials, resulting in nine fabricated HTMs (PT1-PT9), by substituting the terminals with thiophene and acceptors moieties respectively to enhance the photovoltaic properties of perovskite solar cells (PSCs). All newly proposed materials were computationally examined to estimate their optoelectronics, geometrical, and photovoltaic properties using quantum chemical approach, and then compared to the reference. For organic hole-transporting materials, a heterocyclic phenothiazine core (PTZ) has been proven effective as it has feasible structure modifications, excellent electron-donating properties, and straightforward synthesis. The study of electronic parameters (density of state, frontier molecular orbitals, and electrostatic potential ESP), optical properties (light harvesting efficiency, absorption maxima, dipole moment, and first excitation energies) and charge transfer characteristics (electron–hole overlap, transition density matrix) of designed materials revealed that there is an increase in absorption range under the influence of terminal acceptor groups, with lowering the bandgap values compared to the reference. A density of state (DOS) graph and HOMO–LUMO schema are evidence of the electron-withdrawing effect of acceptor moieties. Transition density matrix (TDM) analysis proves reliable charger transfer in designed molecules. Reorganization energy values for designed molecules are lower than the reference making charge transfer carriers more efficient. Additionally, solvation-free energy values (−17.28 to −33.19 Kcalmol−1) and higher dipole moments suggest better surface-wetting and solubility properties. In general, the fabricated materials have exceptional charge mobilities with higher absorption and reduced band gap values that make them suitable and stable candidates for photovoltaic devices.

Understanding the role of porous particle characteristics and water state distribution at multi-scale variation on cellulase hydrolysis of lignocellulosic biomass

Porous particle characteristics of lignocellulosic biomass and the water state distribution surrounding particles determine enzyme/solute transfer, while inherently affecting the liquefaction and hydrolysis reactions. For submillimeter biomass particles (<500 μm), deep eutectic solvent pretreatment tended to create additional macropores (∼4%, pore volume of 4.3 mL/g) and micropores (∼3%, pore area of 2.26 m2/g) at the extragranular and cell wall scales, simultaneously with reducing particle size by 15%. The pretreated biomass exhibited preferential rapid liquefaction over sugar production, leading to a ∼70% reduction in particle size only after 3 h hydrolysis. This further increased particle porosity (∼85% after 12 h hydrolysis) with the transition from large surface-pores to interior micropores. The increases in the tissue/cell-scale pore size and intraparticle area had greater significance for improving hydrolysis performance than particle size reduction. Additionally, particle liquefaction released constrained water in capillary pores and enhanced slurry fluidity; capillary water and free water became main transfer carriers during the hydrolysis. Free water activity was positively related to sugar production (r = 0.80–0.85), and integrating it with particle component and porosity allowed for accurate prediction of hydrolysis yields (R2 = 0.98–0.99). Inspired by particle liquefaction, a short-time feeding strategy was proposed to reconstruct high-solid hydrolysis.

Phosphorus heteroatom doped BiOCl as efficient catalyst for photo-piezocatalytic degradation of organic pollutant and unveiling the mechanism: Experiment and DFT calculation

A novel phosphorus heteroatom doped bismuth oxychloride (P-BiOCl) catalyst was synthesized and the photo-piezocatalytic degradation of rhodamine B dye performances were explored under the ultrasound vibration and light illumination. The P-BiOCl exhibited excellent photo-piezocatalytic degradation activity, such as an ultra-high reaction kinetic rate constant of 0.3961 min−1, efficient degradation efficiency (94.7 % within 8 min) and excellent stability compared to solely piezocatalysis and photocatalysis. More impressively, these outstanding performances of P-BiOCl exceeded pure BiOCl and most other catalytic materials systems. The relevant experimental and density functional theory (DFT) calculation results were exhibited to clarify enhanced photo-piezocatalytic mechanism. The introduction of P heteroatom could reduce the bandgap of BiOCl, modulate electronic structure and charge redistribution, provide novel electron channel to promote electron transfer and restrain charge carriers recombination. Additionally, P-doped could also enhance the adsorption of oxygen and water molecules, promote intrinsic catalytic activity, leading to the increased production of active free radicals ·O2– and ·OH, thus significantly boosting the efficiency of organic pollutant degradation. This work provides a comprehensive understanding of heteroatom doping enhancing photo-piezocatalytic activity and presents a potential new strategy for designing highly efficient catalysts for wastewater treatment.

Efficient hydrogen transfer carriers: hydrogenation mechanism of dibenzyltoluene catalyzed by Mg-based metal hydride

Efficient hydrogen transfer carriers: hydrogenation mechanism of dibenzyltoluene catalyzed by Mg-based metal hydride

Enhancing the performance of paraffin's phase change material through a hybrid scheme utilizing sand core matrix

Smart waste management and valorisation is presented in the current investigation. Iron is collected from mining wastewater stream and augmented with sand as a supporting material to produce sand core. The sand core pellets encapsulated in paraffin’s to enhance its feasibility as phase change material (PCM). Sand core was characterized using X-ray diffraction and Scanning Electron Microscope (SEM) augmented with energy dispersive X-ray spectrum analysis. Experimental test is achieved by mixing sand core/iron and paraffin that is signified as an encapsulated phase change material. The encapsulated sand core-PCM is embedded in varies mass weights of percentages of 0.5, 1.0, 1.5 and 2.0% and labeled as 0.5%-sand core-PCM, 1.0%-sand core-PCM, 1.5%-sand core-PCM and 2.0%-sand core-PCM. The encapsulated sand core-PCM is embedded into a heat exchanger of the vertical type model that is connected with a flat plate solar collector. Such collector is heating the heat transfer carrier, which is exposed to the heat exchanger for melting the PCM. The experimental work is conducted across the solar noon where the solar intensity in the region is reached to 1162 W/m2 at the time of conducting experiments. Water is applied and supposed as the working heat transfer fluid transporter and pumped into the system at the rate of 0.0014 kg per second. The experimental result revealed that the heat gained recorded an enhancement from 7 to 48 kJ/min when the 1.5%-sand core-PCM system is applied. Thus, the results showed the system is a good candidate by increasing the system efficiency with 92% as a potential solution of solar energy storage at the off-time periods.

Metagenomic analysis reveals enhanced sludge dewaterability through acidified sludge inoculation: Regulation of Fe (II) oxidation electron transport pathway

The bioleaching utilizing indigenous microbial inoculation can continuously improve the dewaterability of sludge. In this study, metagenomic analysis was innovative employed to identify the key microorganisms and functional genes that affect the dewatering performance of sludge in the bioleaching conditioning process. The results demonstrated that long-term repeated inoculation of acidified sludge resulted in increased abundance of many functional genes associated with the transport of carbohydrate and amino acid. Additionally, genes encoding key iron transport proteins (such as afuA, fhuC, and fhuD) and genes related to electron transfer carriers in ferrous iron oxidation process (such as rus and cyc2) were significantly enriched, thereby promoting the improvement of sludge dewatering performance through enhanced iron oxidation. Notably, Acidithiobacillus, Betaproteobacteria, and Hyphomicrobium were the major sources of functional genes. This study reveals the microscopic mechanisms underlying the improvement of sludge dewaterability through bioleaching based on mixed culture from a novel perspective of gene metabolism.

Deciphering the Interplay of Structure and Charge Carrier Dynamics in Reduced-Dimensional Perovskites

Reduced-dimensional perovskites (RDPs) have advanced the development of perovskite solar cells (PSCs) due to their tunable energy landscape, structure, and orientation. Thus, we aim for an increase in the understanding of structure-photophysical properties of Dion-Jacobson (DJ) and Ruddlesden-Popper (RP) RDPs with different dimensionalities. Our findings reveal that RP RDPs with lower dimensionality exhibits a dominant n=2 phase, preferential out-of-plane orientation, and longer charge carrier lifetime compared with DJ RDPs, as evidenced by X-ray scattering technique and transient absorption spectroscopy. In addition, we unveil the film growth of respective RDPs by in-situ X-ray scattering, showing the stoichiometry-determined phase growth. The formation of lower-n phases in RP RDPs with higher dimensionality is thermodynamically favored, while those phases are likely in the form of “intermediate phase”, which bridge the 3d-like and lower-n phases in DJ RDPs. DJ RDPs with higher dimensionality demonstrate comparable phase purity, giving rise to more sufficient energy transfer and longer charge carrier lifetime. As such, DJ-based PSCs (n=4) demonstrate better device stability under ISOS-I-L conditions compared to RP-based PSCs. Leveraging these structural and photophysical insights, our work paves the way for dictating the utilization of RDPs in 3D PSCs and the fabrication of quasi-2D solar cells.

Non-volatile magnon transport in a single domain multiferroic

Antiferromagnets have attracted significant attention in the field of magnonics, as promising candidates for ultralow-energy carriers for information transfer for future computing. The role of crystalline orientation distribution on magnon transport has received very little attention. In multiferroics such as BiFeO3 the coupling between antiferromagnetic and polar order imposes yet another boundary condition on spin transport. Thus, understanding the fundamentals of spin transport in such systems requires a single domain, a single crystal. We show that through Lanthanum (La) substitution, a single ferroelectric domain can be engineered with a stable, single-variant spin cycloid, controllable by an electric field. The spin transport in such a single domain displays a strong anisotropy, arising from the underlying spin cycloid lattice. Our work shows a pathway to understanding the fundamental origins of magnon transport in such a single domain multiferroic.

Photoluminescence properties of two-dimensional semiconductor heterointerfaces.

Two-dimensional metal-sulfur compounds have attracted much attention due to their novel physical properties, such as layered structure, ultrathin physical dimensions, and continuously tunable bandgap. The vertical stacking of different 2D semiconductors enables the heterojunction to retain the excellent properties of its constituent materials and has physical properties such as interlayer energy transfer and interlayer carrier transfer. In this paper, we utilize the carrier interlayer transfer properties of p-n heterojunctions and form heterojunctions using p-type Te and PdSe2 prepared with n-type monolayer WS2 using the microzone transfer technique. We found that the PL spectrum of monolayer WS2 is purer after heterojunction formation. The photoluminescence peaks representing exciton recombination are sharper, while the peaks represented by trions almost disappear. These phenomena indicate that we can utilize p-n junctions to capture the PL spectra of excitons in WS2, which is important for the further study of the optical properties of 2D metal-sulfur compounds.

N-doped hollow nanofibers loaded with RuCoNi ternary alloy as an efficient catalyst for hydrogen evolution reaction

Alloying noble metals with abundant transition metals is an effective strategy for preparing cost-effective electrocatalysts for efficient hydrogen evolution reaction. In this study, hollow carbon nanofibers loaded with RuCoNi ternary alloy nanofiber catalysts (RuCoNi/CNFs) were synthesized by coaxial electrostatic spinning and a high-temperature carbonization approach. The interconnected three-dimensional hollow nanofibers, uniformly loaded with RuCoNi alloy nanoparticles, provided a large specific surface area and a hierarchical porous structure to enhance the interaction between the electrolyte and the active sites. Additionally, the hollow structure facilitated active sites exposure, charge transport, and gas diffusion, resulting in excellent HER activity of RuCoNi/CNFs. The overpotential required to achieve a current density of 10 mA cm−2 under alkaline conditions was only 47 mV, outperforming the homemade Pt/C catalyst (54 mV). Moreover, the carbon structure acted as a conductive carrier for efficient electron transfer, protecting the alloy nanoparticles from aggregation and corrosion. The RuCoNi/CNFs demonstrated remarkable stability and durability, maintaining consistent performance even after 100 hours of continuous operation. Importantly, the catalyst also exhibited favorable HER activity (186 mV@100 mA cm−2) at high current density, highlighting its potential for practical applications in large-scale industry.

Simultaneous Emerging Contaminant Removal and H2O2 Generation Through Electron Transfer Carrier Effect of Bi─O─Ce Bond Bridge Without External Energy Consumption.

Conventional advanced oxidation processes (AOPs) require significant external energy consumption to eliminate emerging contaminants (ECs) with stable structures. Herein, a catalyst consisting of nanocube BiCeO particles (BCO-NCs) prepared by an impregnation-hydrothermal process is reported for the first time, which is used for removing ECs without light/electricity or any other external energy input in water and simultaneous in situ generation of H2O2. A series of characterizations and experiments reveal that dual reaction centers (DRC) which are similar to the valence band/conducting band structure are formed on the surface of BCO-NCs. Under natural conditions without any external energy consumption, the BCO-NCs self-purification system can remove more than 80% of ECs within 30min, and complete removal of ECs within 30min in the presence of abundant electron acceptors, the corresponding second-order kinetic constant is increased to 3.62 times. It is found that O2 can capture electrons from ECs through the Bi─O─Ce bond bridge during the reaction process, leading to the in situ production of H2O2. This work will be a key advance in reducing energy consumption for deep wastewater treatment and generating important chemical raw materials.

Highly enhanced Quantum dot light-emitting diode performance by controlling energy resonance in inorganic insertion layers

Quantum-dot light-emitting diodes (QLED) have become a research trend in the field of new displays due to their low cost, wide color gamut, narrow bandwidth, and characteristics that enable production through the solution-gel method. However, the electrical performance of QLED is consistently constrained by energy losses and imbalanced charge carrier injection. This motivates our focus on exciton recombination and energy losses within the quantum-dot layer to enhance the electrical efficiency of QLED. In this work, we introduce a method using a CdZnS quantum dot (B-QD) interlayer to modulate energy transfer and charge carrier transport in QLED devices employing CdSe quantum dot (G-QD) as the emissive layer. By strategically incorporating a B-QD layer between the G-QD and HTL/ETL, we facilitate energy transfer due to the overlap between the excitation wavelength of B-QD and the absorption wavelength of G-QDs. This leads to enhanced energy injection in QLED devices, resulting in a high current efficiency of 39.54 Cd/A and a peak brightness of 522,272 cd/m2 for efficient QLED. The corresponding external quantum efficiency (EQE) is greatly improved from 5.62 % to 9.4 %. Our work provides a straightforward and effective approach to modulate exciton recombination and energy injection and further can be applicable to other photo-electronics devices.

Label free quantitative proteomic profiling of serum samples of intellectually disabled young patients revealed dysregulation of complement coagulation and cholesterol cascade systems.

Intellectual disability is a heterogeneous disorder, diagnosed using intelligence quotient (IQ) score criteria. Currently, no specific clinical test is available to diagnose the disease and its subgroups due to inadequate understanding of the pathophysiology. Therefore, current study was designed to explore the molecular mechanisms involved in disease perturbation, and to identify potential biomarkers for disease diagnosis and prognosis. A total of 250 participants were enrolled in this study, including 200 intellectually disabled (ID) subjects from the subgroups (mild, moderate, and severe) with age and gender matched healthy controls (n = 50). Initially, IQ testing score and biochemical profile of each subject was generated, followed by label-free quantitative proteomics of subgroups of IQ and healthy control group through nano-LC/MS- mass spectrometry. A total of 310 proteins were identified, among them198 proteins were common among all groups. Statistical analysis (ANOVA) of the subgroups of ID showed 142 differentially expressed proteins, in comparison to healthy control group. From these, 120 proteins were found to be common among all subgroups. The remaining 22 proteins were categorized as exclusive proteins found only in disease subgroups. Furthermore, the hierarchical cluster analysis (HCL) of common significant proteins was also performed, followed by PANTHER protein classification and GO functional enrichment analysis. Results provides that the datasets of differentially expressed proteins, belong to the categories of immune / defense proteins, transfer carrier proteins, apolipoproteins, complement proteins, protease inhibitors, hemoglobin proteins etc., they are known to involvein immune system, and complement and coagulation pathway cascade and cholesterol metabolism pathway. Exclusively expressed 22 proteins were found to be disease stage specific and strong PPI network specifically those that have significant role in platelets activation and degranulation, such as Filamin A (FLNA). Furthermore, to validate the mass spectrometric findings, four highly significant proteins (APOA4, SAP, FLNA, and SERPING) were quantified by ELISA in all the study subjects. AUROC analysis showed a significant association of APOA4 (0.830), FLNA (0.958), SAP (0.754) and SERPING (0.600) with the disease. Apolipoprotein A4 (APOA4) has a significant role in cholesterol transport, and in modulation of glucose and lipid metabolism in the CNS. Similarly, FLNA has a crucial role in the nervous system, especially in the functioning of synaptic network. Therefore, both APOA4, and FLNA proteins represent good potential for candidate biomarkers for the diagnosis and prognosis of the intellectual disability. Overall, serum proteome of ID patients provides valuable information of proteins/pathways that are altered during ID progression.

Effect of traditional solvent on thermal decomposition mechanism of lignin: A density functional theory study

In order to understand the effect of traditional solvents on lignin pyrolysis, the decarbonylation and decarboxylation reactions of various phenylic lignin model compounds were theoretically investigated using DFT methods at M06-2×/6–31++G(d,p) level. The calculation results show that activation energy of the decarbonylation and decarboxylation reactions of lignin model compounds can be reduced when H2O/CH3OH existed. There are two types of reaction for the H2O/CH3OH during the pyrolysis. For first type, the synergistic reaction of lignin with H2O/CH3OH as hydrogen transfer carrier. The energy barriers of the main elemental reaction steps during this type of pyrolysis are about 285.0–300.0 kJ/mol (H2O) and 275.0–290.0 kJ/mol (CH3OH) (decarbonylation), 170.0–210.0 kJ/mol and 155.0–200.0 kJ/mol (decarboxylation). For another type, the synergistic reaction of lignin with H2O/CH3OH as hydrogen source. The energy barriers of the main elemental reaction steps during this type of pyrolysis are about 260.0–278.0 kJ/mol and 240.0–260.0 kJ/mol, 303.0–312.0 kJ/mol and 291.0–297.0 kJ/mol. Furthermore, the reaction temperature has the most significant impact on decomposition reaction of lignin in a methanol medium, suggesting that the reaction in the methanol medium is better than that in the water environment.

Rapid Determination of the Optimum Thickness of Doped TiO2 Nanotubes Layer by Local Photoelectrochemistry and Operando Properties Extraction by Data Modeling.

In this work, the optimal thickness of TiO2, M‐doped, N‐doped, and (M:N) codoped TiO2 (with M = Nb or Ta) nanotubes (NTs) for photoelectrochemical (PEC) water splitting is determined, in one step through local photoelectrochemical analysis of electrodes with variable thickness of the photoactive material. A simple anodization method allows the growth, on a single electrode, of aligned doped TiO2 nanotubes whose length gradually changes from 0 to 15 μm. The external quantum efficiency (EQE) as a function of the NTs film thickness is measured using a small beam of UV or visible light to scan the surface and locally trigger the oxygen evolution reaction (OER). The results provide the optimal NT layer thickness for each type of doped TiO2‐NTs and demonstrate that if the (M:N) codoped TiO2‐NTs have the best activity in the visible region, the optimal layer thickness is reduced compared to TiO2 or M:doped TiO2‐NTs. Additionally, by fitting the data with a model that incorporates charge carrier transfer and light absorption mechanisms in the film, it becomes possible to evaluate in operando the interfacial charge transfer, absorption coefficient or majority carrier mean path which are important properties of semiconducting (SC) materials for PEC applications.This article is protected by copyright. All rights reserved.

Taurine-Functionalized Carbon Nanotubes as Electrode Catalysts for Improvement in the Performance of Vanadium Redox Flow Battery

The vanadium redox flow battery (VRFB) is a highly favorable tool for storing renewable energy, and the catalytic activity of electrode materials is crucial for its development. Taurine-functionalized carbon nanotubes (CNTs) were prepared with the aim of augmenting the redox process of vanadium ions and enhancing the efficiency of the VRFB. Sulfonated CNTs were synthesized through a simple modification process in a taurine solution and used as electrocatalysts for redox reactions involving VO2+/VO2+ and V2+/V3+. The SO3H-CNTs modified at 60 °C for 2 h exhibit the best electrocatalytic activity, showing higher redox peak current values compared to pristine carboxylated CNTs (COOH-CNTs). Sulfonic acid groups added to the surface of CNTs increase active sites for redox reactions and act as carriers for mass transfer and bridges for charge transfer, accelerating the rate of the electrode reactions. A battery consisting of SO3H-CNTs as catalysts demonstrates the outstanding charge–discharge performance at a current density of 300 mA∙cm−2. This configuration displays voltage and energy efficiencies of 81.46% and 78.83%, respectively, representing enhancements of 6.15% and 6.12% compared to that equipped with conventional graphite felts (75.31%, 72.71%). This study illustrates that taurine-functionalized carbon nanotubes serve as an efficient and promising catalyst for both the anode and cathode, leading to the improved performance of the VRFB.