Improved Charge Transfer Properties Research Articles

Chemoresistive Gas Sensors Based on Electrospun 1D Nanostructures: Synergizing Morphology and Performance Optimization.

Gas sensors are essential for safety and quality of life, with broad applications in industry, healthcare, and environmental monitoring. As urbanization and industrial activities intensify, the need for advanced air quality monitoring becomes critical, driving the demand for more sensitive, selective, and reliable sensors. Recent advances in nanotechnology, particularly 1D nanostructures like nanofibers and nanowires, have garnered significant interest due to their high surface area and improved charge transfer properties. Electrospinning stands out as a promising technique for fabricating these nanomaterials, enabling precise control over their morphology and leading to sensors with exceptional attributes, including high sensitivity, rapid response, and excellent stability in harsh conditions. This review examines the current research on chemoresistive gas sensors based on 1D nanostructures produced by electrospinning. It focuses on how the morphology and composition of these nanomaterials influence key sensor characteristics-sensitivity, selectivity, and stability. The review highlights recent advancements in sensors incorporating metal oxides, carbon nanomaterials, and conducting polymers, along with their modifications to enhance performance. It also explores the use of fiber-based composite materials for detecting oxidizing, reducing, and volatile organic compounds. These composites leverage the properties of various materials to achieve high sensitivity and selectivity, allowing for the detection of a wide range of gases in diverse conditions. The review further addresses challenges in scaling up production and suggests future research directions to overcome technological limitations and improve sensor performance for both industrial and domestic air quality monitoring applications.

Synergistic effects of Co-Mn co-doping on the structural and optical properties of TiO2 nanospheres: Dual functions for DSSC photoanodes and degradation photocatalyst

Synthesizing direct solar irradiance-responsive nanomaterial capable of serving as an efficient photoanode for dye-sensitized solar cells (DSSCs) and active photocatalysts for organic pollutant elimination poses a formidable challenge. This study focused on the synthesis of cobalt and manganese co-doped titanium dioxide (TiO2) nanoparticles via sol-gel technique, enhancing their efficacy in both the DSSCs and methylene blue (MB) dye degradation. X-ray diffraction and Raman analysis confirm the existence of a tetragonal crystal structure with the anatase phase of TiO2, while XPS analysis verifies the successful integration of cobalt and manganese ions into the host lattices. BET analysis has confirmed that Co, Mn co-doped TiO2 exhibits a higher pore volume and specific surface area compared to the undoped TiO2 material. FESEM and HR-TEM reveals spherical shape morphology and EDS mapping confirms the purity of synthesized nanoparticles. Moreover, Co-Mn co-doped TiO2 nanoparticles exhibits a shift in the optical absorption edge towards the visible spectrum in UV-DRS analysis. PL analysis suggests a diminished electron-hole recombination within the doped and co-doped sample. Electrochemical impedance spectroscopy demonstrates improved charge transfer properties. DSSCs employing the co-doped TiO2 exhibit significantly enhanced power conversion efficiency (4.99 %) compared to bare TiO2 (2.03 %), cobalt-doped (2.61 %), and manganese-doped TiO2 (3.97 %). Additionally, it demonstrates exceptional photocatalytic activity, with 87.83 % (Co-Mn co-doped TiO2) degradation efficiency with a lesser time extent for the methylene blue dye degradation. These findings underscore the potential of Co-Mn co-doped TiO2 for addressing dual challenges in renewable energy (DSSC) and environmental remediation (Pollutant removal).

CuNi sulphidation maximizes MOR activity by expanding the accessibility of active sites!

Sulphidation of a CuNi alloy of Cu : Ni ratio 81 : 19 led to an exponential activity enhancement in the alkaline methanol oxidation reaction (MOR) by four fold due to an order of magnitude increase in the number of active Cu and Ni sites and improved charge transfer properties.

Tailoring the solar cell efficiency of Y-series based non-fullerene acceptors through end cap modification

Y-series-based non-fullerene acceptors (NFAs) have achieved significant deliberation by chemists and physicists because the promising optical and photochemical properties associated with high-performance OSCs can be further tuned through end-capped modification. In this work, such modifications of Y-series benzothiadiazole-based NFAs were accomplished theoretically to propose new acceptors for photovoltaic cells (PVCs). The recently synthesized Y-series non-fullerene acceptor m-BTP-PhC6 was taken as a reference acceptor. We designed five new acceptors (BTP1-BTP5) through the structural modification at both ends of acceptor groups and evaluated their performance by applying DFT and TD-DFT. The newly engineered molecules exhibited a narrower bandgap (Eg) than the reference (R) resulting in better intramolecular charge transfer (ICT). Further, the designed acceptors expressed the maximum absorption in the region of 600–800 nm revealing a redshift in their absorption spectrum. Low excitation energy and low exciton binding energy were noted for designed acceptors confirming them as better candidates for high PCE of solar cells. Low reorganizational energy for the mobility of holes and electrons was also observed for the designed molecules, indicating improved charge transfer properties. The newly tailored acceptor BTP4 was found to be the promising candidate among all acceptors because of lower bandgap, lower exciton binding energy, reorganizational energy, and redshift of the absorption spectrum. The complex analysis of BTP4 with donor polymer PTB7-Th and PM6 was executed at the same DFT level. Furthermore, FMOs studies showed relatively rich electron density in the acceptor groups of LUMO as compared to the reference molecule. The overall theoretical results of this study showed that the designed acceptors played a productive and effective role in uplifting the efficiency of fullerene-free energy devices.

Conservation of Nickel Ion Single‐Active Site Character in a Bottom‐Up Constructed π‐Conjugated Molecular Network

AbstractOn‐surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building‐blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On‐surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π‐extended two‐dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single‐active site character of their single‐molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom‐up constructed covalent nanomeshes.

Conservation of Nickel Ion Single-Active Site Character in a Bottom-Up Constructed π-Conjugated Molecular Network.

On-surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building-blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On-surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π-extended two-dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single-active site character of their single-molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom-up constructed covalent nanomeshes.

Oxygen Vacancy-Mediated Z-Scheme Charge Transfer in a 2D/1D B-Doped g-C3N4/rGO/TiO2 Heterojunction Visible Light-Driven Photocatalyst for Simultaneous/Efficient Oxygen Reduction Reaction and Alcohol Oxidation.

Hydrogen peroxide (H2O2) is a powerful oxidant that directly or indirectly oxidizes many organic and inorganic contaminants. The photocatalytic generation of H2O2 is achieved by using a semiconductor photocatalyst in the presence of alcohol as a proton source. Herein, we have synthesized oxygen vacancy (Ov)-mediated TiO2/B-doped g-C3N4/rGO (TBCN@rGO) ternary heterostructures by a simple hydrothermal technique. Several characterization techniques were employed to explore the existence of oxygen vacancies in the crystal structure and investigate their impact on the optoelectronic properties of the catalyst. Oxygen vacancies offered additional sites for adsorbing molecular oxygen, activating alcohols, and facilitating electron migration from TBCN@rGO to the surface-adsorbed O2. The defect creation (oxygen vacancy) and Z-scheme mechanistic pathways create a suitable platform for generating H2O2 by two-electron reduction processes. The optimized catalyst showed the highest photocatalytic H2O2 evolution rate of 172 μmol/h, which is 1.9 and 2.5 times greater than that of TBCN and BCN, respectively. The photocatalytic oxidation of various lignocellulose-derived alcohols (such as furfural alcohol and vanillyl alcohol) and benzyl alcohol was also achieved. Photocatalytic activity data, physicochemical and optoelectronic features, and trapping experiments were conducted to elucidate the structure-activity relationships. The TBCN@rGO acts as a multifunctional Z-scheme photocatalyst having an oxygen vacancy, modulates surface acidity-basicity required for the adsorption and activation of the reactant molecules, and displays excellent photocatalytic performance due to the formation of a large number of active surface sites, increased electrical conductivity, improved charge transfer properties, outstanding photostability, and reusability. The present study establishes a unique strategy for improving H2O2 generation and alcohol oxidation activity and also provides insights into the significance of a surface vacancy in the semiconductor photocatalyst.

The γ-radiated g-C3N4 additive for highly conductive electron transport layer in polymer solar cells

The electron transport layer (ETL) plays a pivotal role in polymer solar cell (PSC) for improving the efficiency. TiO2 is widely used as ETL, but it has low electron mobility and poor conductivity. Here, we demonstrated the incorporation of the novel γ-radiated g-C3N4 additive into the TiO2-based ETL polymer solar cell. The γ-radiated g-C3N4 tunes the surface morphology of the ETL into smoother and denser film relatively than the reference film. The γ-radiated g-C3N4 modified ETL also shows improved charge transfer properties. As a result, the device with modified ETL containing γ-radiated g-C3N4 additives shows a double enhancement of PCE with respect to the reference device.

Facile synthesis and efficient photoelectrochemical reaction of WO3/WS2 core@shell nanorods utilizing WO3∙0.33H2O phase

One-dimensional (1D) WO3/two-dimensional (2D) WS2 heterojunction nanostructures are of great interest in various photoelectrochemical (PEC) and electrochemical applications. In this study, we introduced a simple and effective route to synthesize 2D WS2 shell layer on WO3 nanorods by utilizing WO3∙0.33H2O phase. The formation of WO3∙0.33H2O nanorods was critically affected by hydrothermal reaction temperature. The WO3∙0.33H2O phase was preferentially transformed into hexagonal WO3 and 2D WS2 through oxidation and sulfurization at 450 °C, respectively. The 2D WS2 shell layer was more favorably formed on WO3 nanorods, which were synthesized at 180 °C and possessed a significant amount of WO3∙0.33H2O phase (referred to as W-180), than on WO3 nanorods with predominant monoclinic WO3 phase, which were synthesized at 200 °C (referred to as W-200). Thus, the WO3/WS2 core@shell nanorods from W-180 exhibited significantly enhanced PEC performance because of the improved charge transfer properties attributed to the advantageous heterojunction effect of 1D WO3/2D WS2. The new synthesis route from WO3∙0.33H2O phase to 2D WS2 can be applied to synthesize various WO3/2D WS2 heterojunction nanostructures, such as thin films, nanoparticles, and nanorods.

Improved Photoelectrochemical Performance of MoS2 through Morphology-Controlled Chemical Vapor Deposition Growth on Graphene.

The morphology of MoS2 nanostructures was manipulated from thin films to vertically aligned few-layer nanosheets on graphene, in a controllable and practical manner, using metalorganic chemical vapor deposition. The effects of graphene layer and MoS2 morphology on photoelectrochemical (PEC) performance were systematically studied on the basis of electronic structure and transitions, carrier dynamic behavior, and PEC measurements. The heterojunction quality of the graphene/vertical few-layer MoS2 nanosheets was ensured by low-temperature growth at 250−300 °C, resulting in significantly improved charge transfer properties. As a result, the PEC photocurrent density and photoconversion efficiency of the few-layer MoS2 nanosheets significantly increased upon the insertion of a graphene layer. Among the graphene/MoS2 samples, the few-layer MoS2 nanosheet samples exhibited shorter carrier lifetimes and smaller charge transfer resistances than the thin film samples, suggesting that vertically aligned nanosheets provide highly conductive edges as an efficient pathway for photo-generated carriers and have better electronic contact with graphene. In addition, the height of vertical MoS2 nanosheets on graphene should be controlled within the carrier diffusion length (~200 nm) to achieve the optimal PEC performance. These results can be utilized effectively to exploit the full potential of two-dimensional MoS2 for various PEC applications.

Stretchable, Fully Polymeric Electrode Arrays for Peripheral Nerve Stimulation.

There is a critical need to transition research level flexible polymer bioelectronics toward the clinic by demonstrating both reliability in fabrication and stable device performance. Conductive elastomers (CEs) are composites of conductive polymers in elastomeric matrices that provide both flexibility and enhanced electrochemical properties compared to conventional metallic electrodes. This work focuses on the development of nerve cuff devices and the assessment of the device functionality at each development stage, from CE material to fully polymeric electrode arrays. Two device types are fabricated by laser machining of a thick and thin CE sheet variant on an insulative polydimethylsiloxane substrate and lamination into tubing to produce pre‐curled cuffs. Device performance and stability following sterilization and mechanical loading are compared to a state‐of‐the‐art stretchable metallic nerve cuff. The CE cuffs are found to be electrically and mechanically stable with improved charge transfer properties compared to the commercial cuff. All devices are applied to an ex vivo whole sciatic nerve and shown to be functional, with the CE cuffs demonstrating superior charge transfer and electrochemical safety in the biological environment.

Synthesis of conductive polyaniline-carbon nanofiber nanocomposite with chenille like morphology for photocatalytic coatings applications

Pristine carbon nanofibers (CNF) have been dispersed with a non-ionic surfactant, Triton X-100 and then acid oxidized (in H2SO4: HNO3, acid ratio 3:1). This ensures a consistent dispersion with attachments of water soluble functional groups (−COOH and OSO3H). Subsequently polyaniline (PANICNF) based nanocomposites, were prepared at low temperature (0–5) ˚C via in-situ polymerization approach. Triton X-100 facilitates the dispersion of bundled CNF, thereby assisting PANI molecules to uniformly coat the edge and surface sites of CNF. This gives rise to a unique core-shell structure with chenille like appearance (PANI@CNF), implying emeraldine PANICNF nanocomposite forms an interpenetrating network. A bandgap of∼1.37 eV as compared to PANI (3.17 eV) calculated using UV–vis Tauc plot curve fit shows that this unique morphology proves to be a boon for the photocatalytic coating formulation. Spectroscopic study also show that the obtained quinoid to benzenoid ring peak ratio for PANI is 1:0.992 and for PANI/CNF is 1:0.996 which is almost equal to one and is thus highly conductive. CNF prompts enhanced polaron movement from valence to conduction band in PANI/CNF while also acting as the acceptor layer to the quinoid rings in PANI which is the donor layer. A linear ohmic graph for PANI/CNF coatings was obtained using I–V (current-voltage) characteristic curves. Thus PANI/CNF nanocomposite coatings possessing a unique fuzzy fabric (chenille) like core-shell morphology has a tunable band gap, enhanced surface area and improved charge transfer properties and are potentially active photovoltaic coatings for environmentally exposed surfaces.

Controllable low-temperature growth and enhanced photoelectrochemical water splitting of vertical SnS2 nanosheets on graphene

Two-dimensional (2D) SnS2 nanosheets vertically grown on graphene electrodes have still not been demonstrated despite their considerable research interest and potential for photoelectrochemical (PEC) applications. Herein, the controllable growth and enhanced PEC water-splitting performance of vertically aligned 2D SnS2 nanosheets on graphene are reported. The heterojunction quality of the graphene/2D SnS2 nanosheets was ensured by low-temperature growth at 230 °C using metalorganic chemical vapor deposition, resulting in significantly improved charge transfer properties. The PEC photocurrent density and photoconversion efficiency significantly increased upon insertion of a graphene layer. In addition, the 2D SnS2 nanosheet microscopic structure dependency of the PEC performance was systematically studied. The best PEC reactivity of the 2D SnS2 nanosheets was achieved at a height of ∼0.85 µm, corresponding to nearly the limit of the carrier diffusion length, and a thickness of ∼70 nm to balance the low interfacial contact resistance with an effective photogenerated carrier dynamics. These results, including the low-temperature vertical growth of 2D SnS2 on graphene, can effectively be utilized to exploit the full potential of 2D SnS2 for various PEC applications.

Improvement of dye-sensitized solar cell performance through introducing TiO2 in acetylene carbon black-graphite composite electrode

In this work, we have investigated the performance of acetylene carbon black/graphite (AB/G) composite counter electrodes (CEs) by incorporating TiO2 as a binder in dye-sensitized solar cells (DSSCs). We obtained five types of composite CE films at different weight ratios of 0:1, 1:3, 1:1, 3:1 and 1:0 by adding a constant amount of TiO2 to a mixture of AB/G. The performance of the composite electrodes was assessed by using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, electrochemical impedance spectroscopies and photocurrent density–voltage characteristics. The results have shown enhanced DSSC efficiency due to improved charge transfer properties of the CE when adding TiO2. TiO2 enhances the binding of the electrode to the substrate. AB/G/TiO2 composites show superior overall results compared to AB/TiO2 and G/TiO2. Since AB has high catalytic activity and surface area, as the AB content of the composite is increased, the electrochemical properties of the CEs are improved. The DSSC with AB:G (3:1) exhibited the maximum power conversion efficiency (PCE) of 5.9% with the highest fill factor (FF) of 0.55, which are comparable to those DSSCs employing platinum CEs with PCE of 6.2% and FF of 0.67.

Surface passivation of zinc ferrite nanorod photoanodes by spray-deposited silicon oxide layer for enhanced solar water splitting

Abstract ZnFe2O4 nanorods (NR's) were prepared by a chemical conversion method from β-FeOOH NRs grown on FTO substrates. To activate their photoactivity of ZnFe2O4 NRs for solar water splitting, the surface passivation was achieved with SiO2 layer via facile and effective spray pyrolysis method. The presence of SiO2 layer enhances the photocurrent density of the Pristine ZnFe2O4 from 143 µA/cm2 to 212 µA/cm2 at 1.23 VRHE for 0.25 mM Si–ZnFe2O4, representing two time increment in the photocurrent density. The influences of amount of Si precursor (Tetraethyl orthosilicate) solutions on the physical properties and the passivation effect of SiO2/ZnFe2O4 interfaces were investigated. This improved photoresponse of the Si-treated ZnFe2O4 NRs was attributed to the excellent charge transfer electrode/electrolyte interface. The effectively improved charge transfer properties of the Si-treated ZnFe2O4 NRs were demonstrated by the electrochemical impedance spectroscopy (EIS), Mott–Schottky (MS) and intensity-modulated photocurrent spectroscopy (IMPS) analyses.

Efficient indoor p-i-n hybrid perovskite solar cells using low temperature solution processed NiO as hole extraction layers

Hybrid perovskites have received tremendous attention due to their exceptional photovoltaic and optoelectronic properties. Among the two widely used perovskite solar cell device architectures of n-i-p and p-i-n, the latter is interesting in terms of its simplicity of fabrication and lower energy input. However this structure mostly uses PEDOT:PSS as a hole transporting layer which can accelerate the perovskite solar cell degradation. Hence the development of stable, inorganic hole extraction layers (HEL), without compromising the simplicity of device fabrication is crucial in this fast-growing photovoltaic field. Here we demonstrate a low temperature (~100 °C) solution - processed and ultrathin (~6 nm) NiO nanoparticle thin films as an efficient HEL for CH3NH3PbI3 based perovskite solar cells. We measure a power conversion efficiency (PCE) of 13.3% on rigid glass substrates and 8.5% on flexible substrates. A comparison with PEDOT:PSS based MAPbI3 solar cells (PCE ~ 7.9%) shows that NiO based solar cells have higher short circuit current density and improved open circuit voltage (1.03 V). Apart from the photovoltaic performance under 1 Sun, the efficient hole extraction property of NiO is demonstrated for indoor lighting as well with a PCE of 23.0% for NiO based CH3NH3PbI2.9Cl0.1p-i-n solar cells under compact fluorescent lighting. Compared to the perovskite solar cells fabricated on PEDOT:PSS HEL, better shelf-life stability is observed for perovskite solar cells fabricated on NiO HEL. Detailed microstructural and photophysical investigations imply uniform morphology, lower recombination losses, and improved charge transfer properties for CH3NH3PbI3 grown on NiO HEL.

Morphological and photophysical study in hybrid ternary organic nanoparticles blends

The electron donor-acceptor based hybrid ternary nanostructures remains a frontier area of research in designing novel light harvesting devices. Here we report the morphological and photophysical study in Intra-triad and Inter-triad nanoparticles by using electron donating donor-acceptor-donor (D-A-D) type Diketopyrrolopyrrole (DPP) molecule which imparts the advantages of both polymers and small molecules and non fullerene electron acceptor, Naphthalene diimide (NDI) and fullerene based acceptor, Phenyl-C61-butyric acid methyl ester (PCBM). Both these nanostructures were fabricated by modified mini-emulsion technique. The Intra-triad nanostructure contains DPP, NDI and PCBM molecules inside the same matrix and in case of Inter-triad nanostructure, individual nanoparticles are attached together by electrostatic force. The morphological optimizations in hybrid nanostructures are performed with the help of AFM studies. We have further studied the structure mediated charge transfer phenomena and lifetime decay profiles by time resolved photoluminescence and steady state spectroscopy measurements. Due to the favorable energy levels, DPP molecules have been employed here as donor molecule for cascade energy transfer in ternary heterotriad geometric system. We have further studied the structure mediated charge transfer phenomena and lifetime decay profiles by time resolved photoluminescence and steady state spectroscopy measurements. Due to the favorable energy levels, DPP molecules have been employed here as donor molecule for cascade energy transfer in ternary heterotriad geometric system. The steady state and time resolved spectroscopy reveal interesting photophysics about the ternary heterostructures. The Intra-triad system has shown improved charge transfer properties compared to Inter-triad system and could be a futuristic material for opto-electronic applications.

In situ growth of orthorhombic Sb2WO6 hierarchical structures on reduced graphene oxide (RGO) sheets via solvothermal approach for superior and substantially improved visible-light driven photocatalytic activity

We report the solvothermal synthesis of reduced graphene oxide (RGO)-hierarchical orthorhombic Sb2WO6 structures with improved electron transfer and reduced charge recombination for visible light driven photocatalysis. The composites were fabricated via a facile solvothermal route by in situ growth of Sb2WO6 hierarchical structures on GO sheets. GO sheets were reduced to RGO during the course of reaction. The optimal ratio for optimum synergetic effect of RGO–Sb2WO6 composite was found to be 9 wt% of RGO. It was found that this type of synthetic approach helps to develop an efficient interfacial contact between Sb2WO6 hierarchical structures and RGO sheets which helps to improve the photocatalytic efficiency by reducing the electron–hole recombination. The pure and composite samples were characterized by XRD, SEM, TEM, FTIR, Raman, BET, DRS and PL analysis techniques. The improved charge transfer properties were proved by photoluminescence (PL) analysis. The photocatalytic performance of the as prepared composites was evaluated by the degradation of non-azo dye Rhodamine B (RhB) and visible light inactive phenol. The improved photocatalytic performance was attributed to the effective charge transfer and hence reduced charge recombination between Sb2WO6 and RGO achieved from the strong interaction between RGO and Sb2WO6. The synthesised composite was also found to be highly stable in cyclic experiments.

Se-doped CuO NPs/H2O2/UV as a highly efficient and sustainable photo-Fenton catalytic system for enhanced degradation of 4-bromophenol

Abstract Brominated aromatic compounds including bromophenols are hazardous and are being fast recognized as priority pollutants. We present here a novel photo-Fenton based degradation system using selenium doped copper oxide nanoparticles (Se-doped CuO NPs)/H2O2/UV, which facilitated 99.5% degradation of 4-bromophenol in 90 min at a rate of 0.057 min−1. The Se-doped CuO NPs are prepared by precipitation method, and their structural, morphological and optical properties are characterized. The selenium doping is chosen owing to its favorable photo-absorption property and its doping in CuO NPs improved charge transfer properties and resulted in enhanced in-situ generation of hydroxyl radicals. The selenium doping also restricted the growth of CuO crystals, due to which the surface area of the nanoparticles increased and led to higher rate of photochemical reaction. The degradation profile is measured by high performance liquid chromatography method. The photo-Fenton process is initiated by extraneous H2O2 and the reaction is sustained by the in-situ generation of hydroxyl radicals, as demonstrated from the ROS scavenger studies. The de-bromination, formation of 4-benozoquinone as an intermediate degradation product and production of anionic species in residual solution after degradation due to cleavage of the molecular structure of 4-bromophenol are the key events confirmed by ion chromatography and gas chromatography coupled with mass spectrometry studies. The robustness of the Se-doped CuO NPs as catalyst has been confirmed from the re-usability studies for seven cycles.

A thin CdSe shell boosts the electron transfer from CdTe quantum dots to methylene blue.

CdTe core and CdTe/CdSe core/shell quantum dots (QD) are investigated with steady state and time-resolved spectroscopic methods. The coating of the CdTe core with a 0.7 nm thick CdSe shell shifts the lowest exciton absorption band to the red by more than 70 nm making the CdTe/CdSe QD an interesting candidate for application in solar energy conversion. Femtosecond transient absorption measurements are applied to study the photoinduced electron transfer (ET) to the molecular acceptor methylene blue (MB). ET times after single excitation of the QD are determined for different MB : QD ratios. The ET reaction is significantly faster in the case of the MB-CdTe/CdSe QD complexes, indicative of an altered charge distribution in the photoexcited heterostructure with a higher electron density in the CdSe shell. As a result of the efficient absorption of incoming light and the faster ET reaction, the amount of reduced MB in the time resolved experiments is higher for CdTe/CdSe QD compared to CdTe QD.