Dual-Ion Co-intercalation Mechanism on a Na2V6O16·3H2O Cathode with a Commercial-Level Mass Loading for Aqueous Zinc-Ion Batteries with High Areal Capacity.

A proton (H+) and zinc ion (Zn2+) co-insertion model is put forward in this study to elucidate the capacity origin of an aqueous zinc ion battery (ZIB) based on a heavily loaded (∼15 mg cm-2) cathode, which consists of Na2V6O16·3H2O (NVO) embedded particularly in the macropores of activated carbon cloth (ACC), coupled with a highly stable Zn/In anode. The confinement effect of these porous channels not only prevents the detachment of NVO from ACC but also well mitigates its volume change resulting from H+ and Zn2+ co-intercalation, which collectively render the stability of NVO/ACC markedly enhanced. Moreover, the bicontinuous structure of NVO/ACC, as a result of the self-interlacing of intrapore NVO, which is first engineered into the nanobelts, and their interlocking with the carbon fibers of ACC, simultaneously giving rise to a solid and a holey framework, is favorable to the electron and ion transport throughout the entire electrode. The synergistic effect of such facile charge transfer kinetics and the high packing density of NVO in the cathode endows ZIBs with not only a good rate performance but also an exceptional areal capacity amounting to 4.6 mAh cm-2, far surpassing those reported for additional vanadium-based counterparts reported in the literature.

Highly Efficient Recovery of H2 from Industrial Waste by Sunlight-Driven Photoelectrocatalysis over a ZnS/Bi2S3/ZnO Photoelectrode.

Hydrogen (H2) fuel production from hazardous contaminants is not only of economic importance but also of significance for the environment and health. Hydrogen production is exemplified in this work by using bismuth sulfide (Bi2S3) sandwiched in between zinc sulfide (ZnS) and zinc oxide (ZnO) as dual-heterojunction photoelectrode to photoelectrochemically extract H2 from sulfide- and sulfite-containing wastewater, which is emitted in enormous quantities from the petrochemical industries. The H2 evolution rate over the ZnS/Bi2S3/ZnO photoelectrode under solar illumination amounts to 112.8 µmol cm-2 h-1, of which the photocurrent density in the meantime reaches 10.7 mA cm-2, by far exceeding those reported for additional Bi2S3-based counterparts in the literature. Such superior performance is ascribed on one hand to the broadband sunlight-harvesting ability of Bi2S3 that gives rise to respectable photoexcited electron-hole pairs. These photogenerated charge carriers are subsequently rectified by the built-in electric field at the ZnS/Bi2S3 and Bi2S3/ZnO heterojunctions to flow in the opposite directions to well circumvent the recombination losses and, most importantly, in turn contribute substantially to the H2 evolution reaction.

Defective Indium Tin Oxide Forms an Ohmic Back Contact to an n-Type Cu2O Photoanode to Accelerate Charge-Transfer Kinetics for Enhanced Low-Bias Photoelectrochemical Water Splitting.

In significant contrast to the tremendous research efforts mostly geared to addressing the severe hole accumulation at the back contact of a p-type Cu2O photocathode with a fluorine-doped tin oxide (FTO) substrate, sluggish electron transfer from an n-type Cu2O photoanode to a tin-doped indium oxide (ITO) substrate has been largely overlooked. To tackle this issue that has been reported to largely limit the photoelectrochemical performance of n-type Cu2O photoanodes at a low bias, the present contribution puts forward a strategy to introduce oxygen vacancies into the ITO substrate via an unprecedented yet facile electrochemical approach. Such defect engineering turns out to decrease the work function of the ITO substrate, which in turn approaches the conduction band extremum of n-Cu2O to highly efficiently extract the photoexcited electrons therein. Moreover, the dendritic growth of n-Cu2O is, in the meantime, interfered by the oxygen vacancy manifested as pinholes distributed over the ITO substrate, which is thereby crystallized into several small grains with augmented surface roughness that is in favor of the injection of the photoexcited hole into the electrolyte. Such facile interfacial charge-transfer kinetics leads to a significant cathodic shift amounting to 200 mV of the onset potential to 0 VAg/AgCl, whereat the n-Cu2O photoanode deposited on the defective ITO substrate delivers the maximum photocurrent density reaching 2 mA cm-2 and, more significantly, its applied bias photon-to-current efficiency (ABPE) reaches 1.1%, which is among the highest performance reported to date for a variety of state-of-the-art metal oxide-based photoanodes in the literature.

Benchmarked capacitive performance of a 330 µm-thick NaxV2O5/CC monolithic electrode via synergism of a hierarchical pore structure and ultrahigh-mass-loading.

To address the longstanding issue of conventional supercapacitors, viz. their energy and power deliveries are largely attenuated by the poor packing density of particularly the active electrodes, an ultracompact yet porous monolithic electrode is put forward in the present study. Particularly, it is built on electroactive α'-NaxV2O5 with the areal mass loading amounting to 33.24 mg cm-2 densely packed into a 330-µm-thick carbon cloth and more importantly, with a hierarchical meso-/nano-pore structure in favor of the ion transport throughout this 330 µm-thick α'-NaxV2O5/CC heavy electrode. In such context, a series of superior performances including the areal, gravimetric and volumetric capacitances reaching 12.47 F cm-2, 375.2 F g-1 and 377.93 F cm-3, and the energy and power densities amounting to 1.38 mW h cm-2 and 34.1 mW cm-2 are successfully delivered by this compact monolith at the electrode- and device-level, respectively, altogether outperforming significantly those of additional modern and promising electrodes and energy storage devices reported in the literature.

Ultrafast Carrier Transport through an Advanced Thick Electrode with a High Areal Capacity for Aqueous Lithium-Ion Batteries.

Thick electrode design holds great promise to render the aqueous lithium ion battery more cost effective by boosting the packing density of the electroactive materials to enhance the energy delivery at the device level. However, a thick electrode faces the concomitant challenge of the sluggish transport of electrons and, importantly, the Li ions. To address this issue, numerous 3 D shortcuts that include a conductive percolation network and well-interconnected mesoporous channels were established in the 330 µm thick V2 O5 ⋅H2 O/CC monolithic electrode developed here. In this way, electron transfer and ion transport were favored, which accounts for the outstanding charge-storage capacity that exceeded 2 mA h cm-2 and the exceptional energy and power densities of 1.38 mW h cm-2 and 34.1 mW cm-2 , respectively, measured at the electrode and the device scale within a short subhour timeframe. Such a remarkable high rate performance is better than that of electrodes reported previously for commercial lithium-ion microbatteries, advanced aqueous batteries, and state-of-the-art supercapacitors designed for high-power applications.

Enhancing the quasi-theoretical photocurrent density of ZnO nanorods via a lukewarm hydrothermal method.

A ∼10-µm-long one-dimensional (1D) ZnO nanorod array (NRA) vertically oriented on a fluorine-doped tin oxide (FTO) coated glass substrate is successfully fabricated via a lukewarm hydrothermal method. The reflection of light from the rough surface of this ultralong ZnO NRA, resulting from the variation in the characteristic length of individual ZnO NRs in a tapered geometry, is largely suppressed. This in turn favors the ZnO NRA as a photoelectrode effectively harnessing UV-light for solar water splitting, as evidently manifested in the quasi-theoretical photocurrent density that reached ∼0.9 mA cm-2 at 1VAg/AgCl. A further contribution to such an outstanding performance stems from additional photocurrent generation by the ZnO NRA upon visible light illumination. This is attributed to a variety of native defects and the surface hydroxyl groups present in the ZnO NRA, giving rise to the mid-gap states that mediate the associated electronic transitions. Moreover, those lattice imperfections further boost the carrier concentration of the ZnO NRA to facilitate the carrier transport which in turn enhances the photoelectrochemical activity.

Higher NAFLD fibrosis score is associated with impaired eGFR.

BACKGROUND/PURPOSE: Chronic kidney disease (CKD) has become a worldwide health problem, leading to high morbidity and mortality, and non-alcoholic fatty liver disease (NAFLD) is considered a risk factor for CKD. The aim of this study was to explore the relationship between NAFLD fibrosis score (NFS) and the estimated glomerular filtration rate (eGFR), and identify possible risk factors related to the NFS among Taiwanese subjects. METHODS: Subjects were enrolled from the database of the Department of Preventive Medicine of Kaohsiung Municipal Hsiao-Kang Hospital. The eGFR was calculated according to the Taiwanese Modification of Diet in Renal Disease (TMDRD) equation, and the NFS was employed to evaluate the fibrotic level. RESULTS: In total, 11,376 subjects were enrolled in this study, with a mean age of 52.0 ± 6.81 years, including 4529 (39.8%) males. A fasting sugar level ≥100 mg/dL (OR = 1.70, 95% CI = 1.52-1.87) and an abnormal waist circumference (OR = 1.81, 95% CI = 1.65-1.99) were significant factors associated with NFS (p < 0.05). Trends of a decreasing TMDRD score and an increasing NFS with increasing age were noted (p < 0.05). The NFS was significantly negatively correlated with the TMDRD score (standard coefficients: -0.067, p < 0.001). CONCLUSION: A higher NFS is associated with an impaired eGFR in Taiwanese subjects. Controlling risk factors, especially fasting sugar level and waist circumference, may be useful in preventing NFS deterioration, which is negatively correlated with the eGFR.

Defect-Cluster-Boosted Solar Photoelectrochemical Water Splitting by n-Cu2 O Thin Films Prepared Through Anisotropic Crystal Growth.

Anisotropic growth of Cu2 O crystals deposited on an indium-doped tin oxide-coated glass substrate through facile electrodeposition and low-temperature calcination results in favorable solar photoelectrochemical water splitting. XRD, TEM, and SEM reveal that appreciable oxygen vacancies are populated in the Cu2 O crystals with a highly branched dendritic thin film morphology, which are further substituted by Cu atoms to form Cu antisite defects exclusively along the [111] direction. The post-thermal treatment presumably accelerates such migration of the lattice imperfections, favoring the exposure of the catalytically active (111) facets. The Cu2 O thin film derived in this way shows n-type conduction with a donor concentration in the order of 1017  cm-3 and a flat-band potential of -1.19 V vs. Ag/AgCl, which is also confirmed by Mott-Schottky analysis. The material is employed as a photoanode and delivers a photocurrent density of 2.2 mA cm-2 at a potential of 0.3 V vs. Ag/AgCl, surpassing reported values more than twofold. Such superiority mostly originates from the synergism of the selective facet exposure within the Cu2 O crystals, which have decent crystallinity, as shown by Raman and photoluminescence spectroscopy, and a favorable bandgap of 2.1 eV, as confirmed by UV/Vis spectroscopy. The n-type Cu2 O thin film reported herein holds excellent promise for solar-related applications.

Novel p-n heterojunction copper phosphide/cuprous oxide photocathode for solar hydrogen production.

A Copper phosphide (Cu3P) micro-rod (MR) array, with coverage by an n-Cu2O thin layer by electrodeposition as a photocathode, has been directly fabricated on copper foil via simple electro-oxidation and phosphidation for photoelectrochemical (PEC) hydrogen production. The morphology, structure, and composition of the Cu3P/Cu2O heterostructure are systematically analyzed using a scanning electron microscope (SEM), X-ray diffraction and X-ray photoelectron spectra. The PEC measurements corroborate that the p-Cu3P/n-Cu2O heterostructural photocathode illustrates efficient charge separation and low charge transfer resistance to achieve the highest photocurrent of 430 µA cm-2 that is greater than other transition metal phosphide materials. In addition, a detailed energy diagram of the p-Cu3P/n-Cu2O heterostructure was investigated using Mott-Schottky analysis. Our study paves the way to explore phosphide-based materials in a new class for solar energy applications.

Branched silver nanowires on fluorine-doped tin oxide glass for simultaneous amperometric detection of H2O2 and of 4-aminothiophenol by SERS.

This study introduces a two-step method for the deposition of branched silver nanowires (AgNWs) on fluorine-doped tin oxide (FTO) glass. This material serves as both an active surface-enhanced Raman-scattering (SERS) substrate and as an enzyme-free electrochemical sensor for H2O2. This dual functionality is systematically studied. The AgNWs as the main trunk were first deposited on FTO by spray-coating. Silver branches were then electrochemically produced on the preformed NWs. Scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectrometry were employed to characterize morphology, composition and microstructure. SERS experiments show that the branched AgNW/FTO substrate exhibits excellent performance in detecting 4-aminothiophenol at an ultra-low concentration of 0.1 fM. Simultaneously, this material displays an excellent electrocatalytic response to H2O2 reduction at a concentration as low as 1 µM. The sensor has a rapid response and two linear analytical ranges that extend from 0.25 to 300 µM, and from 0.3 to 2.6 mM of H2O2, respectively. The ultrahigh sensitivity and satisfactory reproducibility highlights the merit of this hierarchical AgNW dendritic structure for sensing applications. Graphical abstract Branched silver nanowires can serve as both an active surface-enhanced Raman scattering substrate and as an electrochemical sensor for H2O2. This dual functionality is systematically investigated.

Au@Nb@H x K1-xNbO3 nanopeapods with near-infrared active plasmonic hot-electron injection for water splitting.

Full-spectrum utilization of diffusive solar energy by a photocatalyst for environmental remediation and fuel generation has long been pursued. In contrast to tremendous efforts in the UV-to-VIS light regime of the solar spectrum, the NIR and IR areas have been barely addressed although they represent about 50% of the solar flux. Here we put forward a biomimetic photocatalyst blueprint that emulates the growth pattern of a natural plant-a peapod-to address this issue. This design is exemplified via unidirectionally seeding core-shell Au@Nb nanoparticles in the cavity of semiconducting H x K1-xNbO3 nanoscrolls. The biomimicry of this nanopeapod (NPP) configuration promotes near-field plasmon-plasmon coupling between bimetallic Au@Nb nanoantennas (the peas), endowing the UV-active H x K1-xNbO3 semiconductor (the pods) with strong VIS and NIR light harvesting abilities. Moreover, the characteristic 3D metal-semiconductor junction of the Au@Nb@H x K1-xNbO3 NPPs favors the transfer of plasmonic hot carriers to trigger dye photodegradation and water photoelectrolysis as proofs-of-concept. Such broadband solar spectral response renders the Au@Nb@H x K1-xNbO3 NPPs highly promising for widespread photoactive devices.

Synthesis of Cu2O nanoparticle films at room temperature for solar water splitting.

A Cu2O nanoparticle film using ZnO nanorods as a sacrificial scaffold was fabricated near 23°C, for applications in photoelectrochemical (PEC) water splitting. Three chemical solutions were utilized to convert ZnO nanorods to a Cu2O nanoparticle film - solutions of CuCl2 and NaOH, NaBH4 and NaOH, respectively. The structural evolution from ZnO through Cu(OH)2 and metallic Cu to Cu2O phase was analyzed at each stage with X-ray diffraction and X-ray absorption spectra. The energy bandgap was deduced from IPCE; the concentration of carriers and flat-band of a Cu2O nanoparticle film were obtained from a Mott-Schottky plot. Significantly, the Cu2O nanoparticle film exhibited a useful PEC response to water oxidation. This nanostructure synthesized with no energy requirement can not only illustrate a great prospect for solar generation of hydrogen but also offer a blueprint for the future design of photocatalysts.

Thermally activated Cu/Cu2S/ZnO nanoarchitectures with surface-plasmon-enhanced Raman scattering.

Hierarchical Cu/Cu2S/ZnO nanoarchitectures were fabricated via an electroplated ZnO nanorod array in the first step, followed by the growth of Cu2S nanostructures for the application of surface-enhanced Raman scattering (SERS) detection. The Cu/Cu2S nanostructures as grown were thermally treated at 150-300°C under a nitrogen atmosphere to improve the crystalline quality, and, unexpectedly, to induce plasmonic Cu nanoshells on the surface of Cu2S. With 4-aminothiophenol (4-ATP) as probing molecules, SERS experiments showed that the thermally treated Cu/Cu2S/ZnO nanostructures exhibit excellent detection performance, so that they can serve as active and cost-effective SERS substrates for ultrasensitive detection. The enhancement is attributed to the coupling between Cu2S and plasmonic Cu, as confirmed by electromagnetic field simulations. This novel hierarchical substrate shows satisfactory reproducibility and a linear dependence of intensity on analyte concentration, revealing an advantage of this method for easily scaled production.

Graphene oxide as the passivation layer for Cu(x)O photocatalyst on a plasmonic Au film and the corresponding photoluminescence study.

The contribution of graphene oxide (GO) on photocatalytic effects of Cu(x)O on plasmonic Au is investigated. It is found that the H(2) evolution rate from pure water is enhanced 1.4 fold using the visible-active Cu(x)O/GO photocatalyst, as compared with Cu(x)O without GO. In addition, the intensity of photoluminescence of Cu(x)O/GO can be enhanced as much as 2.85 fold as compared with Cu(x)O without GO. The enhancement is due to the negative fixed charge in GO, which can passivate the surface of Cu(x)O and suppress recombination of minority electrons at the surface. The results from optical characterization in this study can help to prove the proposed mechanism of passivation.

Novel ZnO/Fe2O3 Core-Shell Nanowires for Photoelectrochemical Water Splitting.

A facile and simple fabrication of Fe2O3 as a shell layer on the surface of ZnO nanowires (NW) as a core-shell nanoelectrode is applied for the photoelectrochemical (PEC) splitting of water. An ZnO NW array of core diameter ∼80 nm was grown on a fluorine-doped tin-oxide (FTO) substrate with a hydrothermal method; subsequent deposition and annealing achieved a shell structure of the Fe2O3 layer of thickness a few nm. Fe2O3 in the α phase and ZnO in the wurtzite phase were identified as the structures of the shell and core, respectively, through analysis with X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The ZnO/Fe2O3 core-shell NW showed an excellent PEC response to the oxidation of water, and also benefited from a negative shift of onset potential because of an n/n heterojunction structure. A detailed energy diagram of the ZnO/Fe2O3 core-shell NW was investigated with a Mott-Schottky analysis. This novel core-shell nanostructure can hence not only exhibit a great potential for the solar generation of hydrogen, but also offer a blueprint for the future design of photocatalysts.

Cobalt-phosphate-assisted photoelectrochemical water oxidation by arrays of molybdenum-doped zinc oxide nanorods.

We report the first demonstration of cobalt phosphate (Co-Pi)-assisted molybdenum-doped zinc oxide nanorods (Zn(1-x)Mo(x)O NRs) as visible-light-sensitive photofunctional electrodes to fundamentally improve the performance of ZnO NRs for photoelectrochemical (PEC) water splitting. A maximum photoconversion efficiency as high as 1.05% was achieved, at a photocurrent density of 1.4 mA cm(-2). More importantly, in addition to achieve the maximum incident photon to current conversion efficiency (IPCE) value of 86%, it could be noted that the IPCE of Zn(1-x)Mo(x)O photoanodes under monochromatic illumination (450 nm) is up to 12%. Our PEC performances are comparable to those of many oxide-based photoanodes in recent reports. The improvement in photoactivity of PEC water splitting may be attributed to the enhanced visible-light absorption, increased charge-carrier densities, and improved interfacial charge-transfer kinetics due to the combined effect of molybdenum incorporation and Co-Pi modification, contributing to photocatalysis. The new design of constructing highly photoactive Co-Pi-assisted Zn(1-x)Mo(x)O photoanodes enriches knowledge on doping and advances the development of high-efficiency photoelectrodes in the solar-hydrogen field.

Silver-decorated hierarchical cuprous oxide micro/nanospheres as highly effective surface-enhanced Raman scattering substrates.

A facile and simple route to manufacture active surface-enhanced Raman scattering (SERS) substrate based on Ag-decorated Cu2O micro/nanospheres on Cu foil was systematically investigated. Hierarchical Cu2O micro/nanostructure transfers from CuO nanosheets and Cu(OH)2 nanowires by means of thermally reducing the oxides from Cu2+ to Cu1+ at temperature of 500 °Cunder nitrogen atmosphere. The subsequent decoration of Ag on Cu2O nanostructural substrate was carried out by means of thermal evaporator deposition. Using 4-aminothiophenol (4-ATP) as probing molecules, the SERS experiments showed that the Ag-decorated Cu2O micro/nanospheres exhibit excellent detecting performance, which could be used as effective SERS substrate for ultrasensitive detection. Additionally, these novel hierarchical SERS substrates showed good reproducibility and a linear dependence between analyte concentrations and intensities, revealing the advantage of this method for easily scale-up production.

Photoelectrochemical activity on Ga-polar and N-polar GaN surfaces for energy conversion.

Hydrogen generation through direct photoelectrolysis of water was studied using photoelectrochemical cells made of different facets of free-standing polar GaN system. To build the fundamental understanding at the differences of surface photochemistry afforded by the GaN {0001}and {000-1}polar surfaces, we correlated the relationship between the surface structure and photoelectrochemical performance on the different polar facets. The photoelectrochemical measurements clearly revealed that the Ga-polar surface had a more negative onset potential relative to the N-polar surface due to the much negative flat-band potential. At more positive applied voltages, however, the N-polar surface yielded much higher photocurrent with conversion efficiency of 0.61% compared to that of 0.55% by using the Ga-polar surface. The reason could be attributed to the variation in the band structure of the different polar facets via Mott-Schottky analyses. Based on this work, understanding the facet effect on photoelectrochemical activity can provide a blueprint for the design of materials in solar hydrogen applications.

Novel iron oxyhydroxide lepidocrocite nanosheet as ultrahigh power density anode material for asymmetric supercapacitors.

A simple one-step electroplating route is proposed for the synthesis of novel iron oxyhydroxide lepidocrocite (γ-FeOOH) nanosheet anodes with distinct layered channels, and the microstructural influence on the pseudocapacitive performance of the obtained γ-FeOOH nanosheets is investigated via in situ X-ray absorption spectroscopy (XAS) and electrochemical measurement. The in situ XAS results regarding charge storage mechanisms of electrodeposited γ-FeOOH nanosheets show that a Li(+) can reversibly insert/desert into/from the 2D channels between the [FeO6 ] octahedral subunits depending on the applied potential. This process charge compensates the Fe(2+) /Fe(3+) redox transition upon charging-discharging and thus contributes to an ideal pseudocapacitive behavior of the γ-FeOOH electrode. Electrochemical results indicate that the γ-FeOOH nanosheet shows the outstanding pseudocapacitive performance, which achieves the extraordinary power density of 9000 W kg(-1) with good rate performance. Most importantly, the asymmetric supercapacitors with excellent electrochemical performance are further realized by using 2D MnO2 and γ-FeOOH nanosheets as cathode and anode materials, respectively. The obtained device can be cycled reversibly at a maximum cell voltage of 1.85 V in a mild aqueous electrolyte, further delivering a maximum power density of 16 000 W kg(-1) at an energy density of 37.4 Wh kg(-1).

Surface Plasmon assisted Cu(x)O photocatalyst for pure water splitting.

In this paper, Cu(x)O photocatalyst on plasmonic nanoporous Au film is proposed to enhancing the H(2) evolution rate of pure water splitting. The nanoporous Au film can simultaneously provide surface-enhanced absorption and built-in potential. The reflection spectrum shows that the surface plasmon (SP) assisted absorption wavelength of the Cu(x)O on the nanoporous Au film can be modified by changing the annealing temperature. It is found that the enhancement of the H(2) evolution rate highly depends on the SP-assisted absorption. As the annealing temperature is 220 ° C, the H(2) evolution rate is 58 µmol hr(-1) under the condition that the device area is 0.25 cm(2).