The development of affordable and compact noninvasive point-of-care (POC) dopamine biosensors for the next generation is currently a major and challenging problem. In this context, a highly ...sensitive, selective, and low-cost sensing probe is developed by a simple one-step laser-scribing process of plastic waste. A flexible POC device is developed as a prototype and shows a highly specific response to dopamine in the real sample (urine) as low as 100 pmol/L in a broad linear range of 10−10–10−4 mol/L. The 3D topological feature, carrier kinetics, and surface chemistry are found to improve with the formation of high-density metal-embedded graphene-foam composite driven by laser irradiation on the plastic-waste surface. The development of various kinds of flexible and tunable biosensors by plastic waste is now possible thanks to the success of this simple, but effective, laser-scribing technique, which is capable of modifying the matrix’s electronic and chemical composition.
Engineering of novel functional nanocomposite as like as the metallic nanocrystals supported non-stoichiometric perovskite nanomaterial in controlled parameters (size, shape and ratio of chemical ...characteristics) is a challengeable task. In this context, we present a facile route to fabricate and study its physicochemical property at real time mode in this report. Nanoscale pure Pb crystals surfaced on non-stoichiometric A-site deficient Pb
TiO
nanoparticle were fabricated when a precursor lead titanate (PbTiO
) nanoparticle was exposed to an electron beam irradiation (EBI) in a transmission electron microscope (TEM) at ambient temperature. In the state of the art, the chemical states and electronic structure of non-irradiated and irradiated PbTiO
were studied by X-ray photoelectron spectroscopy (XPS). Electron bombardment resulted in a new visible feature at low binding energy in the Pb 4f core level, while Ti 2p and O 1s line shape showed slight changes. The Fermi level of the corresponding materials was determined to be 1.65 ± 0.1 eV and 2.05 ± 0.1 eV above the valence band maximum, respectively. The normal, weakly p-type PTO exhibits peculiar n-type feature after EBI process (The Fermi level moves near to the conduction band). A feasible mechanism is proposed involving the electron-stimulated local bond-breaking phenomenon in PbTiO
.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Charged domain walls (CDWs) show great potentials to mediate the properties of ferroelectrics. Direct mapping of these domain walls at an atomic scale is of critical importance for understanding the ...domain wall dominated properties. Here, based on aberration‐corrected scanning transmission electron microscopy, tail‐to‐tail CDWs at 71°, 109°, and 180° domains in BiFeO3 thin films have been identified. 2D mappings demonstrate 1D structural modulations with alternate lattice expansions and clockwise/counterclockwise lattice rotations at these CDWs. Such behaviors of CDWs reveal a remarkable contrast to the uncharged domain walls and imply delicate interactions between bound charges and structural compensations of domain wall. These results are expected to provide new information on domain wall structures and shed some light on the understanding of domain wall properties in ferroelectrics.
Atomic level 1D structural modulations are demonstrated at the negatively charged domain walls in BiFeO3 thin films using aberration‐corrected scanning transmission electron microscopy. All the 109º, 180º, and 71º charged domain walls of (100) type reveal similar 1D modulations in terms of alternate lattice expansions and clockwise/counterclockwise lattice rotations. The results will be helpful for understanding the structure and property of domain walls in ferroelectrics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This work investigates a series of BiVO4 with different (010) and (110) facets ratio. The crystal structure, morphology, and photophysical properties of BiVO4 samples were all characterized by XRD, ...FE-SEM, TEM, XPS, PL, UV–vis and BET techniques. Photocatalytic performances of BiVO4 samples with different (010) and (110) facets ratio were evaluated by the O2 evolution and decolorization of thymolblue under the simulated sunlight irradiation. It showed that a positive relationship exists between the photocatalytic activities (O2 evolution) and the (010) facet ratio. The plate-like msBiVO4 exhibited exceptional O2 evolution ability approximately 4 times greater than bipyramid msBiVO4 under the simulated sunlight. The photocatalytic performances of plate-like msBiVO4 mainly originates from the weak-binding effect of (010) facet for photo-generated carrier compared with (110)-dominant msBiVO4. The built-in of inner electric fields directed from (110) facet to (010) facet, further enhancing the transfers of photo-generated electron–hole pairs by the action of potential energy difference. The entirely exposed (110) facet of msBiVO4 in this study provides us with an opportunity to explore the key factor for its photocatalysis.
•The (110)-dominant and (010)-dominant msBiVO4 samples have been successfully synthesized.•The space charge layer width has positive correlation with the percentage of (010)/((110)+(010)) for msBiVO4.•The electric potential difference between (010) and (110) of msBiVO4 is important for efficient carrier separation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fabrication of a highly efficient all solution/substrate processable neurotransmitter sensor by one-step molecular engineering of a 2D-carbon material and the science behind its action.
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•All solution/substrate processable biosensor is developed.•A new form of 3D-crumpled porous-sheet structure is prepared.•3D-crumpled porous-sheet structure act as the molecule capturer-transducer.•Epinephrine is detectable in real samples at 20 pM with rapid readout (2.2 s).•The biosensor has high durability (97%/60 days) and stability (95%/25 cycles).
Designing next-generation affordable compact point-of-care (POC) epinephrine biosensors is a significant and challenging issue at the moment. In this context, all solution/substrate processable sensing material is developed by a simple one-step molecular engineering of 2D-reduced graphene oxide (rGO). As a proof-of-concept, a flexible POC device is fabricated which demonstrates a distinct and selective response to epinephrine down to 13/20 pM in the buffer/real sample solution in a wide linear range of 10-10-10-4 M with rapid readout (2.2 s). Systematic experimental and density functional theoretical (DFT) studies are conducted to uncover the underlying reason for the sensor's remarkable performance. It is found that the precise link between the immobilized molecule p-aminobenzoic acid (PAB) and the 2D-rGO basal plane results in a beneficial change in the 2D-topological feature, charge mobility and interlayer chemistry. Besides, the sensing material functions as biomolecule selector, capturer and transducer via strong H-bond interaction and π-π electron coupling/resonance effect, which leads to enhanced sensitivity and specificity. The achievement of this simple yet efficient molecular engineering technique, which can successfully alter the electronic and chemical arrangement of the 2D matrix, opens up a new avenue for the development of various types of flexible and tunable biosensors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•A novel BiVO4 phase junction was fabricated by one-step hydrothermal route.•The tzBiVO4 component in tzBiVO4/msBiVO4 showed high oxidation ability.•Z-scheme and type-II band ...alignment features were proposed in tzBiVO4/msBiVO4.•Electronic structure and their related photocatalytic nature were found.
Bismuth vanadate (BiVO4) has been one of the most extensively investigated materials in photocatalytic fields owing to its low cost and high performance. Despite much available evidences about its band alignment and photogenerated carrier migration, a convincing explanation of how photogenerated carrier migration occurs in its polymorph phase junction as well as its exact electronic structure has remained elusive. Herein, we designed a high-quality hierarchical tzBiVO4/msBiVO4 phase junction to elucidate the photogenerated carrier migration process and its correlated band alignment. Via the X-ray photoelectron spectroscopy (XPS) and the density functional theory (DFT) calculations, we unveil that a particular band alignment containing Z-scheme and type-II features exists between tzBiVO4 and msBiVO4, where the tzBiVO4 component in tzBiVO4/msBiVO4 showing a higher collecting and oxidizing ability of the photogenerated holes at the designed interface. Importantly, this study offers a new understanding of the BiVO4 atomistic nature of bonding, electronic structure and their related photocatalytic nature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the quest for designing affordable diagnostic devices with high performance, precisely functionalized carbon-based materials with high accuracy and selectivity are required. Every material has its ...own unique ability to interact with the analyte, and its performance can be enhanced by probing the interaction mechanism. Herein, p-aminophenol (PAP)-functionalized reduced graphene oxide (rGO) nanoscale material is developed by a one-step synthetic route as an all-organic-based sensor. As the PAP molecules are precisely covalently interacted with the rGO at the basal plane and form a wrinkled-paper-like structure, the functionalized material exhibits an outstanding sensing ability (7.5 nM neurotransmitter dopamine (DA) at a wide linear range, 0.01–100 μM) with fast electrical transduction (<3 s) and good recyclability (∼10 cycles) in a real sample. Combining various analytical and density functional theory (DFT) calculation methods, physicochemical properties and the interaction mechanism of analyte–materials transduction are discussed exclusively. Besides, the potential application of the well-dispersed rGO-PAP gravure ink in flexible-printed electronics fields is explored. This study not only provides new insights into the surface/interface chemistry and working principle of this unique anchoring of PAP on rGO but also offers a new pathway for developing other forms of metal-free/organic functionalized biosensors with high efficiency.
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IJS, KILJ, NUK, PNG, UL, UM
One of the current key issues in the photocatalysis is to obtain the band alignment of coupled semiconductor experimentally, which is the most significant aspect for understanding the efficient ...photocatalytic activity precisely. In this article, a BiVO4/BiOI{001} heterojunction was detected by the transmission electron microscopy (TEM). The results of electrochemical impedance spectroscopy (EIS) reveal that a higher efficiency of charge immigration across the electrode/electrolyte interface for the BiVO4/BiOI{001}. In addition, the electron lifetime was investigated by the Bode phase plots, which are responsible for the observed photocatalytic behaviors. As a result, the photocatalytic activities for rhodamine B (RhB) degradation and iodine ion oxidation are remarkably increased compared to the individual BiVO4 and BiOI{001}. In fact, a direct band alignment in the BiVO4/BiOI{001} does not give well a logical interpreting on its photocatalytic behavior. However, through the valence-band offset formula, we demonstrated the exact band alignment of corresponding components in the BiVO4/BiOI{001}. This band alignment was further confirmed by the PL spectra, which CM2 with photo-oxidation (Mn2+) is red shift and CM2 with photo-reduction (Ag+) is blue shift compared with CM2.
•BiVO4/BiOI{001} heterojunction were prepared via a facile in situ chemical transformation approach.•The prolonged electrons lifetime of BiVO4/BiOI{001} is responsible for the observed photocatalytic behaviors.•We obtain experimentally the band alignment of BiVO4/BiOI{001} through the valence-band offset.•This band alignment was evidenced by the PL spectra (BiVO4/BiOI{001}.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•BiOI/β-Bi2O3 obtains excellent photocatalytic hydrogen evolution ability.•We unveil the transition dipole moment in BiOI/β-Bi2O3 heterojunction.•Photogenerated electrons are confined ...in β-Bi2O3 component of BiOI/β-Bi2O3.•BiOI/β-Bi2O3 can provide proper ΔGH* in hydrogen evolution process.•BiOI/β-Bi2O3/H2O interface can lead to a proper electric double layer structure.
In the realm of photocatalysis, understanding the interface issues (solid/solid and solid/liquid) inherent in heterojunction at the atomic level is the ultimate for engineering an efficient photocatalyst. Herein, an electrophoretic deposition technique is adopted to synthesize BiOI/β-Bi2O3 heterojunction, exhibiting superior photocatalytic activity and stability in H2 evolution (91.5 μmol g–1 h−1) and H2O2 production (11.3 mg L–1 h−1). Combined with the experimental and computational results, a lower free energy of hydrogen evolution reaction (252.4 meV) has been observed contrast to BiOI and β-Bi2O3 samples. A carrier transfer process of like S-scheme heterojunction is proposed based on density of states (DOS) and carrier distribution calculations. The theoretical calculations illustrate the transition dipole moment, migration and accumulation of carrier in BiOI/β-Bi2O3 heterojunction. Subsequent ab initio molecular dynamics (AIMD) results of solid/liquid interface systems (BiOI/β-Bi2O3/H2O and β-Bi2O3/H2O) unravel the interface H2O (solvent) behaviors. The local aggregation of photo-generated electrons in BiOI/β-Bi2O3/H2O leads to a large potential drop, high proton migration rate and the steady electric double layer (EDL) structure compared to the β-Bi2O3/H2O, which facilitates the occurrence of photocatalytic reactions in solution. In addition to offering new insights into the hydrogen evolution and proton transfer in the EDL model and the association between the heterojunction effect and EDL structure, this work also introduces a novel design strategy for Bi-based heterojunctions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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