Sun Illumination Conditions Research Articles

Integrating physical model and image simulations to correct topographic effects on surface reflectance

Integrating physical model and image simulations to correct topographic effects on surface reflectance

Microstrain effects of laser-ablated Au nanoparticles in enhancing CZTS-based 1 Sun photodetector devices.

Copper zinc tin sulfide (CZTS) thin films were synthesized on soda lime glass using pulsed laser deposition (PLD) at room temperature. Introducing gold nanoparticles (AuNPs) in a sandwich structure led to increased CZTS particle size and a shift in the localized surface plasmon resonance (LSPR) peak of the AuNPs, influenced by different laser energy levels. The absorption measurements revealed intriguing behavior across the visible and near-infrared (NIR) regions, making these films appealing for 1 Sun photodetectors. Furthermore, the presence of AuNPs in the sandwich structure reduced microstrain effects, measuring 1.94 × 10-3 compared to 3.38 × 10-3 in their absence. This reduction directly enhances carrier transport, which is particularly beneficial for accelerating the performance of photodetector devices. This effect of AuNPs also contributed to higher dielectric coefficients, further improving the photodetector performance. Under 1 Sun illumination conditions, this enhancement resulted in a rapid rising time of 95.4 ms, showcasing the potential for faster photodetection.

CsPbIBr2‐Based Bifacial Semitransparent Solar Cells for All‐Day Applications

Among all‐inorganic perovskites, CsPbIBr2 has become a potential candidate in semitransparent perovskite solar cells (ST‐PSCs) due to its excellent thermal stability and suitable bandgap. Herein, by optimizing the ambient temperature in an N2‐filled glovebox, the growth process of CsPbIBr2 crystals is regulated to avoid the generation of pinholes and improve the photoelectric conversion capacity of perovskite cells. When the ambient temperature is around 25 °C, the champion power conversion efficiency (PCE) of 10.82% with opaque n–i–p structure is achieved. Based on MoOx/Ag/MoOx (20/12/20 nm) multilayer top electrode, the ST‐PSC device achieves a maximum PCE of 7.06% at the fluorine‐doped tin oxide side under the simulated 1 sun illumination condition and a PCE of 23.96% at MoOx/Ag/MoOx electrode side under the intensity of 1000 lux (≈350 μW cm−2) provided by a white light‐emitting diode lamp, along with an average visible transmittance of 29.25%. The resulting perovskite solar cell is the first bifacial inorganic ST‐PSC that could be used under both sunlight and indoor light, which is an important step toward all‐day power generation of inorganic ST‐PSCs and building‐integrated photovoltaics.

PC61BM-based organic solar cells for indoor applications with a power conversion efficiency exceeding 20%

With the development of the Internet of Things (IoT), organic solar cells (OSCs) have shown great potential for efficiently converting indoor light into electricity as a self-suitable power source for IoT systems. Fullerene and its derivatives have been widely used as electron acceptors in indoor OSCs because of their spectral matches and avoidable photodimerization. In this study, the device performance of fullerene PC61BM-based OSCs blended with three different donor polymers was investigated under indoor lighting conditions. The devices demonstrated much higher power conversion efficiencies (PCEs) under dim light conditions than under 1 sun illumination condition. The best-performing PM6:PC61BM normal OSCs exhibited a maximum PCE of 7.94% under 1 sun illumination and 23.27% under a 3200 K light -emitting diode (LED) at 2000 lx. This study suggests the favorable applicability of fullerene-based OSCs for indoor applications and highlights the importance of good spectral matches and energy-level alignment for efficient indoor OSCs.

Surface engineering of Ba-doped TiO2 nanorods by Bi2O3 passivation and (NiFe)OOH Co-catalyst layers for efficient and stable solar water oxidation

The rational design of heterostructures as an ideal photoelectrode system for H 2 and O 2 conversion in photoelectrochemical (PEC) system has been regarded as an essential key to boost PEC performance. In this work, to demonstrate the energetic photoanode cell, deposition of a thin layer of Bi 2 O 3 is utilized to hybridize with the 5 wt% Ba-doped TiO 2 nanorod heterostructure under the cascading band diagram, where Ba-doping can enhance the charge transport/separation rate in bulk phase, in terms of increasing the donor density, enhancing the bulk electronic conductivity, and increasing the band bending. Furthermore, with optimizing the thickness (∼15 nm) of Bi 2 O 3 , the (NiFe)OOH as a cocatalyst was adapted to improve the interfacial charge transfer rate in the PEC cell, reaching the high photocurrent density ( J ) of ∼4.1 mA/cm 2 at 1.23 V (vs. Reversible Hydrogen Electrode) and stability retention of 100%, even after 15 h at 1 M NaOH under 1 Sun illumination condition. The improvement mainly comes from the extended absorption of visible light from the thin Bi 2 O 3 layer, effective transfer/separation of photogenerated charge carriers, and acceleration of water oxidizing reaction, caused by the narrowed band gap and the favorable charge transfer under the cascading band alignment built by the heterojunction, as well as electrocatalyst, offering the timely consumption of photogenerated holes accumulated at the electrode surface. Schematic model representing the energetic charge separation, charge transfer/injection at the interface and surface of the (NiFe)OOH/Bi 2 O 3 /Ba (5%):TNR arrays. • Ba (5 wt%)-doped TiO 2 nanorods are synthesized via a hydrothermal route. • Bi 2 O 3 and (NiFe)OOH cocatalyst layers are adapted to achieve the high J of ∼4.1 mA/cm 2 at 1.23 V RHE . • Bi 2 O 3 layer induced to narrowing of band gap as well as the cascading band alignment built by the heterojunction.

Hierarchical micro/nano/porous structure PVDF/hydrophobic GO photothermal membrane with highly efficient anti-icing/de-icing performance

Frequent icing and frosting cause severe economic losses and, more seriously, may endanger life of human beings. Efficient strategies for anti-icing remain to be developed. Superhydrophobic surface is considered an effective anti-icing material. Nevertheless, it still has disadvantages of complicated operation steps and difficulty in large-scale preparation, and its freezing time is limited while ice will increase rapidly once its surface is frozen. Herein, hierarchical micro/nano/porous superhydrophobic coatings with photothermal property were prepared, which combined active and passive de-icing/anti-icing properties. Hydrophobic graphene oxide (GO) was introduced to PVDF substrate to facilitate formation of hierarchical micro/nano/porous structures. Therefore, superhydrophobicity and photothermal properties were both achieved. In addition, porous structures and folds on the inner wall provide more traps and longer trajectories for incident light, and thus the possibility of absorbing sunlight increased dramatically due to multiple reflections, therefore enhancing the solar-to-heat conversion efficiency. The superhydrophobic property endowed the membrane with excellent anti-icing performance, moreover, the freezing time of PVDF+GOF (10%) was 213 s and it was 14 times that of the untreated glass surface. What’s more, within 3 min, the temperature of PVDF+GOF(10%) coating can rise from 20 °C to 72 °C or from − 10–11 °C under 1 sun illumination condition. Hence, the photothermal superhydrophobic material can remain unfrozen for a long time in the low temperature and the fast, effective preparation method will expand practical application of superhydrophobic surfaces.

A super absorbent resin-based solar evaporator for high-efficient various water treatment

Currently, water treatment has been viewed as an important way to the growing shortage of fresh water. A solar vapor generation device demonstrated enormous potential for desalination, water purification and carbon emission reduction. Nevertheless, the high cost and scalability hurdles of solar evaporators fundamentally restrict the practicality of solar-driven water treatment. In this study, an industrialized sodium polyacrylate (PAANa) super absorbent resin together with commercial carbon nanotubes (CNTs) is used to construct a PAANa-based solar evaporator. Under synergistic effects of high photothermal conversion efficiency, larger actual evaporation area, and reasonable water distribution on the evaporation surface, PAANa-based solar evaporator achieves a high water evaporation rate of 7.47 kg m−2 h−1 under 1 sun illumination (1 kW m−2) and convective flow condition. Notably, many kinds of sewage including dye-containing sewage, seawater, oil-in-water emulsion, and real industrial sewage can be effectively purified by using PAANa-based solar evaporator. Moreover, in arid and water-deficient areas, the PAANa-based evaporator with a strong water extraction capacity can easily capture water from gravel crevices and simultaneously purify it for further use. Significantly, under natural sunlight irradiation, a large-area PAANa-based evaporator (about 415 cm2) provided a sewage treatment capacity of up to 11.93 kg m− 2 for a continuous 10 h. This study will offer a new possibility for the industrialization of cost-effective and scalable solar evaporators, which can be used to alleviate the global water resources shortages.

Effect of SnO2 incorporation on the photoelectrochemical properties of α-Fe2O3–SnO2 nanocomposites prepared by hydrothermal method

In this work, we report the effect of tin oxide (SnO 2 ) incorporation on the photoelectrochemical (PEC) water oxidation activity of hematite-tin oxide (α-Fe 2 O 3 –SnO 2 ) nanocomposites prepared by hydrothermal method. During synthesis of α-Fe 2 O 3 –SnO 2 , the proportions of SnO 2 in the composites were varied from 5 wt% to 50 wt%. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. XRD results showed diffraction signals from both α-Fe 2 O 3 and SnO 2 in the composite structure. The surface morphology and size features of α-Fe 2 O 3 altered drastically with addition of SnO 2 . TEM analysis revealed that small-sized SnO 2 were coated on the surface of α-Fe 2 O 3 , forming heterogeneous grain boundary interfaces. The α-Fe 2 O 3 –SnO 2 nanocomposites were tested as photoanode for PEC water oxidation under standard 1 Sun illumination condition in 1 M NaOH. Among the various compositions, α-Fe 2 O 3 –SnO 2 (50 wt%) displayed promising water splitting photocurrent density of 0.32 mAcm −2 at 1.4 V versus RHE, which is a 5-fold higher as compared to the photocurrent density of pure α-Fe 2 O 3 (0.06 mAcm −2 ). This enhancement in photocurrent density can be attributed to the reduced electron-hole recombination as a result of better charge separation at local heterojunction between α-Fe 2 O 3 and SnO 2 in the composite. • α-Fe 2 O 3 –SnO 2 nanocomposites are prepared with a simple hydrothermal method. • SnO 2 incorporation promotes the water oxidation photoactivity of hematite. • The desirable composite electrode adds to electron-holes separation and transport.

Low-Cost and Efficient Nickel Nitroprusside/Graphene Nanohybrid Electrocatalysts as Counter Electrodes for Dye-Sensitized Solar Cells.

Novel nickel nitroprusside (NNP) nanoparticles with incorporated graphene nanoplatelets (NNP/GnP) were used for the first time as a low-cost and effective counter electrode (CE) for dye-sensitized solar cells (DSSCs). NNP was synthesized at a low-temperature (25 °C) solution process with suitable purity and crystallinity with a size range from 5 to 10 nm, as confirmed by different spectroscopic and microscopic analyses. The incorporation of an optimized amount of GnP (0.2 wt%) into the NNP significantly improved the electrocatalytic behavior for the redox reaction of iodide (I−)/tri-iodide (I3−) by decreasing the charge-transfer resistance at the CE/electrolyte interface, lower than the NNP- and GnP-CEs, and comparable to the Pt-CE. The NNP/GnP nanohybrid CE when applied in DSSC exhibited a PCE of 6.13% (under one sun illumination conditions) with the Jsc, Voc, and FF of 14.22 mA/cm2, 0.628 V, and 68.68%, respectively, while the PCE of the reference Pt-CE-based DSSC was 6.37% (Jsc = 14.47 mA/cm2, Voc = 0.635 V, and FF = 69.20%). The low cost of the NNP/GnP hybrid CE with comparable photovoltaic performance to Pt-CE can be potentially exploited as a suitable replacement of Pt-CE in DSSCs.

Process optimization of dip-coated MWCNTs thin-films: Counter electrode in dye sensitized solar cells

Present research article emphasizes the first report on a simple and cost-effective ‘dip and dry’ coating method to coat MWCNTs at room temperature as a counter electrode towards dye sensitized solar cells (DSSCs) with ZnO/Eosin-Y as a photoanode. Process optimization through the number of dips (10, 15, 18, and 20) have been performed and compared to standard platinum (Pt) as counter electrode with iodide-triiodide as a liquid electrolyte. Photovoltaic performance through current density-voltage characteristic under standard 1 Sun illumination condition (AM 1.5G, 100 ​mW/cm 2 ) and external quantum efficiency have been well supported which are correlated through structural, surface morphological, and electrochemical studies. Interestingly, DSSCs device with 18 cycles of MWCNTs yields half of the power conversion efficiency than that of Pt device. • Simple and low-cost ‘dip and dry’ method well controlled via number of dips to coat MWCNTs thin-films to serve as a CE. • MWCNTs thin-films CE are possible replacement of costly platinum (Pt) for DSSCs. • ZnO as a semiconductor material, Eosin-Y as sensitizer, and I - /I 3 - as an electrolyte with Pt coated FTO to assemble DSSCs. • DSSCs device with an optimum coating of MWCNTs yields half of the power conversion efficiency than that of Pt device. • Investigation and analysis of structural, surface morphology, electrochemical, in correlation with solar cell performance.

SPECIFIC FEATURES OF STRUCTURES IN THE INNER COMA OF COMET C/2017 T2 (PANSTARRS) AS OBSERVED WITH THE OMT-800 TELESCOPE OF THE ODESSA OBSERVATORY TELESCOPE NETWORK

Observations of the comet werecarried out using the OMT-800 telescope (the primarymirror diameter D = 80 cm; the focal length F =214 cm) of the Odessa Observatory telescope networkfrom January to June 2020. Image processing was per-formed through standard methods using subtraction ofdark and flat field frames. The resulting frames wereemployed to analyse the morphology of the cometaryinner coma using digital filters. Isophotes of the comaand images of its structures appearing as fans and jetswere obtained. The presence of a strong fan, whichdistorts the coma’s standard appearance and makesit elongated perpendicularly to the Sun-comet line, isobserved over the period from January to April. Lateron, a weak jet that hardly affects the coma’s standardshape appears to replace the fan. The jet reaches itspeak intensity near perihelion and then gets fainterrapidly. Such behaviour of the coma structures isindicative of the presence of two active areas on thecometary nucleus surface, for which the matter outflowis governed by the Sun illumination conditions. Oneof these areas, being more active, is responsible for theappearance of a strong fan. The other area, which isfar less active, generates a jet that manifests itself nearperihelion. The peak dust production of the comet120–150 days before perihelion is due to the presenceof an active fan in the inner coma.

Solar Selective Absorbers for High-efficiency Photothermal Conversion via Core–Shell Nanocone Structured Surface

Nanostructured surface, a promising photon management strategy, enables to enhance photon-to-heat conversion efficiency by manipulating spectral radiative properties ranging from solar spectrum (0.3–2.5 μm) to mid-infrared spectrum (2.5–20 μm). Here, a core–shell nanocone structured surface made of silica core and tungsten shell as a solar selective absorber is introduced. The photothermal conversion efficiency (PTCE) is calculated in consideration of solar spectrum absorption and mid-infrared emission. It is obvious that high solar spectrum absorption and low mid-infrared emission are beneficial for high PTCE. The influence of structural parameters on the PTCE is studied, and then the absorption enhancement mechanism is elucidated in detail. Meanwhile, the influences of incident angle, polarized state, and lattice arrangement are also presented. The calculated results exhibit that our optimized solar absorber possesses the total solar absorption of 97.3% and total thermal emission of 7.6%, resulting in a maximum PTCE of 91.4% under one sun illumination conditions at normal incidence. Moreover, our solar selective absorber is independent to the incident angle and polarization state. The excellent photothermal conversion performance with wide-angle and polarization-insensitive properties for the solar selective absorber can serve as a good candidate for various solar thermal applications including seawater desalination, steam generation, thermophotovoltaic, and photocatalysis.

Microvessel‐Assisted Environmental Thermal Energy Extraction Enabling 24‐Hour Continuous Interfacial Vapor Generation

Interfacial solar evaporators have great potential for clean water production; however, their evaporation performance relies greatly on the solar illumination condition, which is restricted by daily sunshine time and climates. Here, a wood-based vapor generator in pyramid structure is fabricated to achieve efficient water evaporation under dark condition (0 kW m-2 ) through efficient extraction of environmental thermal energy. The microvessels of wood provide fast water transportation whereas the tailored pyramid surface structure enables efficient evaporative cooling for extracting energy from the environment. The method enables fast water evaporation without the need of solar heat input. We demonstrate a vapor generation rate of up to 2.15 kg m-2 h-1 under dark condition (0 kW m-2 ), which is even 1.4 times faster than the theoretical limit of conventional solar thermal evaporators working under 1 sun (1 kW m-2 ) illumination condition. During the 24-h continuous evaporation test, the evaporator presented a daily vapor generation rate of up to 50.8 kg m-2 day-1 and 60.7 kg m-2 day-1 on cloudy and sunny day, respectively, offering a novel approach for the development of 24-h full-time water evaporators for seawater desalination and wastewater treatment.

Modeling and Analysis of an Echo Laser Pulse Waveform for the Orientation Determination of Space Debris

Orientation information of space debris is required to improve the orbital prediction accuracy for mitigation or elimination of a significant threat to not only human space activities but also operational satellites. Obtaining orientation information is currently achievable by applying photometry, adaptive optics (AO) and satellite laser ranging (SLR) technologies. In this study, a new method is proposed based on an echo laser pulse waveform (ELPW) for the orientation determination of space debris; its feasibility was also investigated by numerical simulations. Unlike the photometry and AO technologies available just under the sun-illumination condition and the SLR technology applicable only for cooperative targets, the ELPW is achievable by using a high power laser regardless of the above measurement constraints. A mathematical model is derived to generate the ELPW, and the beam broadening and spreading due to the atmospheric turbulence is taken into account. The Gaussian decomposition based on a genetic algorithm was employed to the ELPWs in order to analyze the orientation features. It is demonstrated from the numerical simulations that the ELPWs have distinctive shapes characterizing the orientation of space debris and therefore our approach was capable of providing orientation information.

Understanding the Performance of Organic Photovoltaics under Indoor and Outdoor Conditions: Effects of Chlorination of Donor Polymers.

Understanding the effects of the chemical structures of donor polymers on the photovoltaic properties of their corresponding organic photovoltaic (OPV) devices under various light-intensity conditions is important for improving the performance of these devices. We synthesized a series of copolymers based on poly[(2,6-(4,8-bis(5-(2-thioethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-TS) and studied the effects of chlorine substitution of its thiophene-substituted benzodithiophene (BDT-Th) unit on its photovoltaic properties. Chlorination of the polymer resulted in a bulk heterojunction (BHJ) morphology optimized for efficient charge transport with suppressed leakage current and an increased open-circuit voltage of the OPV device; this optimization led to a remarkable enhancement of the OPV device's power conversion efficiency (PCE) not only under the condition of 1 sun illumination but also under a low light intensity mimicking indoor light; the PCE increased from 8.7% for PBDB-TS to ∼13% for the chlorinated polymers, PBDB-TS-3Cl, and PBDB-TS-4Cl under the 1 sun illumination condition and from 5.3% for PBDB-TS to 21.7% for PBDB-TS-4Cl under 500 lx fluorescence illuminance. Interestingly, although the OPV PCEs under 1 sun illumination were independent of the position of chlorine substitution onto the polymer, PBDB-TS-4Cl exhibited better performance under simulated indoor light than its derivative PBDB-TS-3Cl. Our results demonstrate that efficient light absorption and charge-carrier generation play key roles in achieving high OPV efficiency under low-light-intensity conditions.

Synthesis of transparent Zr-doped ZnFe2O4 nanocorals photoanode and its surface modification via Al2O3/Co–Pi for efficient solar water splitting

Abstract The Zr-doped ZnFe2O4 (Zr-ZFO) nanocorals photoanode have been synthesized from Zr-doped FeOOH (Zr–FeOOH) nanocorals on fluorine-doped tin oxide (FTO) substrate followed by Al2O3/Co–Pi surface modification for effective PEC water splitting. The hydrothermal method was adopted for the synthesis of in situ Zr doping in FeOOH, while Zr-ZFO nanocorals was fashioned by subsequent additional procedures, such as Zn(NO3)2 precursor dropping, first quenching, etching and second quenching. The Al2O3 layer decreases the over-potential of the Zr-ZFO photoanode‖electrolyte interface as well as lowers the charge transfer resistance which aids to increase in the photocurrent density from 0.24 mA/cm2 to 0.36 mA/cm2 at 1.23 V vs. RHE under 1 sun illumination condition. The subsequent loading of cobalt phosphate (Co–Pi) as a co-catalyst leads to an improved photocurrent density of 0.49 mA/cm2 at 1.23 V vs. RHE. These synergistic effects of Zr doping and surface modification led to remarkable improvement in photocurrent density from 0.19 mA/cm2 (at 1.4 V vs. RHE) for conventional ZFO nanorods to 0.65 mA/cm2 for the Zr-ZFO/Al2O3/CoPi photoanode. A systematic investigation into the effect of Zr doping and Al2O3/Co–Pi overlayer reveals the reduction of two distinct recombination processes (bulk and surface) in ZFO photoanode.

Impedance spectroscopy of perovskite/contact interface: Beneficial chemical reactivity effect.

Understanding chemical reactivity of lead halide perovskite materials with contacts is crucial to improve the stability of these optoelectronic devices. The study of the physical and chemical interactions at the interfacial region is still one of the most challenging tasks in this field. We investigate a configuration based on the direct contact of gold (Au) with highly crystalline methylammonium lead bromide perovskite (MAPbBr3), in comparison with the presence of an organic interlayer. The metal contact clearly shows the double layer capacitance that can be monitored by Impedance Spectroscopy (IS). Measurements in the dark reveal the frequencies where a reduction in charge accumulation occurs, related to ionic reactivity with the external contacts. Under light, this chemical reaction is favored and the newly formed contact improves the performance of the solar cell. The IS results show that reactivity proceeds at timescales longer than 100 s, reducing the recombination kinetics under 1 sun illumination conditions, increasing the photovoltage and photocurrent that can be extracted. This work presents IS as a nondestructive in operando tool to monitor the kinetics of the ionic double layer formation and the reactivity of methylammonium bromide perovskite material with contacts decoupling as well this information from other resistive and capacitive contributions.

Highly Efficient Semitransparent Perovskite Solar Cells for Four Terminal Perovskite-Silicon Tandems.

Tandem solar cells (SCs) based on perovskite and silicon represent an exciting possibility for a breakthrough in photovoltaics, enhancing SC power conversion efficiency (PCE) beyond the single-junction limit while keeping the production cost low. A critical aspect to push the tandem PCE close to its theoretical limit is the development of high-performing semitransparent perovskite top cells, which also allow suitable near-infrared transmission. Here, we have developed highly efficient semitransparent perovskite SCs (PSCs) based on both mesoporous and planar architectures, employing Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3 and FA0.87Cs0.13PbI2Br perovskites with band gaps of 1.58 and 1.72 eV, respectively, which achieved PCEs well above 17 and 14% by detailed control of the deposition methods, thickness, and optical transparency of the interlayers and the semitransparent electrode. By combining our champion 1.58 eV PSCs (PCE of 17.7%) with an industrial-relevant low-cost n-type Si SCs, a four-terminal (4T) tandem efficiency of 25.5% has been achieved. Moreover, for the first time, 4T tandem SCs' performances have been measured in the low light intensity regime, achieving a PCE of 26.6%, corresponding to revealing a relative improvement above 9% compared to the standard 1 sun illumination condition. These results are very promising for their implementation under field-operating conditions.

Elucidation of the structural and charge separation properties of titanium-doped hematite films deposited by electrospray method for photoelectrochemical water oxidation

Elemental doping is considered to be an effective strategy to improve the photoelectrochemical (PEC) activity of hematite (α-Fe2O3) as a photoanode for water splitting, but the precise function (s) of the dopant remains unclear. In this study, we report on the structural and charge separation properties of titanium-doped hematite (Ti doped Fe2O3) films prepared by a simple electrospray technique for PEC water oxidation. The effect of Ti doping on the structure, morphology, light absorption, and electrical and photoelectrochemical properties was investigated on α-Fe2O3 films. SEM images revealed a reduction in particle sizes for 2% Ti doped α-Fe2O3, while an increase in particle size was observed for higher Ti content. XRD confirmed the presence of α-Fe2O3 without any impurity or other phases. From XPS spectra, the incorporation of Ti was confirmed in the form of Ti4+ as predominant species while no impurities from the substrate were detected. When the Ti doped Fe2O3 (2% Ti) film was used as a photoanode in a PEC cell, it delivered the best performance with a maximum photocurrent density of 1.09 mA cm−2 (at 1.8 V vs. RHE and under standard 1 sun illumination conditions (AM 1.5 G, 100 mW cm−2)), which is 2 times higher than that of the un-doped α-Fe2O3 (0.51 mA cm−2). The photoelectrode also showed a superior incident photon to current efficiency (IPCE) as compared to an un-doped α-Fe2O3. This enhancement in performance was attributed to the better charge separation and transport properties of α-Fe2O3 due to Ti doping, as revealed by an electrochemical impedance spectroscopy (EIS) analysis.

On The Estimation of Temporal Changes of Snow Water Equivalent by Spaceborne Sar Interferometry: A New Application for the Sentinel-1 Mission

Abstract In this work we present a methodology for the mapping of Snow Water Equivalent (SWE) temporal variations based on the Synthetic Aperture Radar (SAR) Interferometry technique and Sentinel-1 data. The shift in the interferometric phase caused by the refraction of the microwave signal penetrating the snow layer is isolated and exploited to generate maps of temporal variation of SWE from coherent SAR interferograms. The main advantage of the proposed methodology with respect to those based on the inversion of microwave SAR backscattering models is its simplicity and the reduced number of required in-situ SWE measurements. The maps, updated up to every 6 days, can attain a spatial resolution up to 20 m with sub-centimetre ΔSWE measurement accuracy in any weather and sun illumination condition. We present results obtained using the proposed methodology over a study area in Finland. These results are compared with in-situ measurements of ΔSWE, showing a reasonable match with a mean accuracy of about 6 mm.