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With the transfer of the electrochemical CO

Stabilized power output at maximum power point (mpp) has been considered as one of the most reliable parameters as it provides a key performance indicator for perovskite solar cells (PSCs) revealing the operational stability of the photovoltaic device. Here, we show the effect of selective contact on the power output change under mpp tracking, which closely correlates with the charge recombination dynamics with a time scale of minutes. The normal n-i-p cell architecture comprising cp-TiO2/mp-TiO2/perovskite/spiro-MeOTAD (doped by either Li-TFSI or Zn-TFSI2) and the inverted p-i-n structure, NiOx/perovskite/PCBM, are examined to investigate the specific effect of the nature of the interface on operational stability. The normal structure with Li-TFSI shows a gradual performance decrease at mpp owing to the enhanced recombination at the interface between the perovskite and the spiro-MeOTAD, becoming the dominant recombination process, although the bulk-related recombination is suppressed. On the other hand, the inverted structure demonstrates an improved photocurrent at mpp due to the effectively suppressed recombination both in bulk and at the interface. Remarkably, the deteriorating performance of the normal structure with Li-TFSI at mpp is successfully avoided by replacing Li-TFSI with Zn-TFSI2, leading even to an increased power output with stable performance at mpp.

By applying the pulsed polarization technique, a thimble-type lambda probe can be used as a NOx sensor in the low ppm range. Due to the robustness of the sensor in harsh exhaust gas environments, this approach has many opportunities for application. The temperature operating range for best NO sensing properties is a crucial parameter. The sensor temperature changes with the ambient gas temperature, but can be stabilized actively by internal heating in a certain temperature range. This study evaluates in detail the temperature influence on NO sensitivity, so that an optimum operating point can be derived from these results using a dynamic measurement technique. Stepwise NO concentration changes between 0 and 12.5 ppm in synthetic exhausts demonstrate the potential of the concept.

WOS: 000448339100022 Li-TFSI is the most common p-dopant for the hole conductor spiro-MeOTAD in the normal structure (n-i-p) of perovskite solar cells (PSCs), which consistently yield the highest power conversion efficiency (PCE) albeit at the risk of lower long-term operational stability. Here we successfully replace conventional Li-TFSI with Zn-TFSI2, which not only acts as a highly effective p-dopant but also enhances considerably both the photovoltaic performance and long-term stability. The incorporation of Zn-TFSI2 as a dopant for spiro-MeOTAD leads to an increase by one order in the hole mobility compared to Li-TFSI from 3.78 x 10(-3) cm(2) V-1 s(-1) to 3.83 x 10(-2) cm(2) V-1 s(-1). Furthermore, the device with Zn-TFSI2 showed an 80 mV higher built-in voltage and a bigger recombination resistance than the one with Li-TFSI, which were responsible for the striking increase in both the open-circuit voltage and fill factor, leading to a stabilized PCE of 22.0% for the best cells. Remarkably, the device employing Zn-TFSI2 demonstrated superb photo-stability, showing even a 2% increase in the PCE after 600 h light soaking at the maximum power point (mpp) under full sun, while the PCE of the device with Li-TFSI decreased by 20% under the same conditions. Similarly, the device with Zn-TFSI2 showed better operational stability at 50 degrees C resulting in a 21% decrease in the PCE after 100 h aging at the mpp under full sun while the Li-TFSI based one showed a 55% decrease. Moreover, the Zn-TFSI2 based device was capable of effectively resisting humidity compared to the one based on Li-TFSI from shelf stability monitoring (R.H. 40%) in the dark. Coporate Research and Technology Siemens AG, Germany; GRAPHENE Flagship Core 2 project - European Commission H2020 Programme [785219]; TUBITAK - 2214-A International Doctoral Research Fellowship Programme; NRP 70 "Energy Turnaround" This work was supported by a grant from Coporate Research and Technology Siemens AG, Germany. H.-S. K thanks the financial support from the GRAPHENE Flagship Core 2 project supported by the European Commission H2020 Programme under contract 785219 is gratefully acknowledged. J.-Y. S thanks the financial support from the NRP 70 "Energy Turnaround". S. A. would like to thank TUBITAK - 2214-A International Doctoral Research Fellowship Programme, for supporting his research at EPFL.

The direct electro-reduction of CO2 to functional molecules like ethene is a highly desirable variant of CO2 utilization. The formation of, for example, ethene from CO2 is a multistep electrochemical process going through various intermediates. As these intermediates are organic species, the CO2 reducing electro-catalyst has to be competent for a variety of organic functional group transformations to yield the final product. In this work, the activity of an in situ-grown nano-structured copper catalyst towards a variety of organic functional group conversions was studied. The model reagents were selected from the product spectrum of actual CO2 reduction reaction (CO2RR) experiments and from proposals in the literature. The CO2 bulk electrolysis benchmark was conducted at 170 mAcm−2 current density with up to 43% Faradaic Efficiency (FE) for ethene and 23% FE for ethanol simultaneously. To assure relevance for application-oriented conditions, the reactivity screening was conducted at elevated current densities and, thus, overpotentials. The found reactivity pattern was then also transferred to the CO reduction reaction (CORR) under benchmark conditions yielding additional insights. The results suggest that at high current density/high overpotential conditions, also other ethene formation pathways apart from acetaldehyde reduction such as CH2 dimerization are present. A new suggestion for a high current density mechanism will be presented, which is in agreement with the experimental observations and the found activity pattern of copper cathodes toward organic functional group conversion.

To detect NO in the low ppm range in exhaust gases is of high interest due to the ever tighter emission and immission regulations. Applying the pulsed polarization technique, Pt|YSZ sensors like the classical thimble type lambda probes for automotive applications or planar sensor elements (Pt electrodes on both sides of YSZ) show very good sensitivities toward NO. To further improve the sensor with respect to simplicity and robustness for exhaust gas applications, a one-sided design is preferred, especially to implement a heater on the reverse side of the sensor element. For that purpose, a design that bases on platinum interdigital electrodes is investigated. Again, by using this polarization technique very strong signals towards NO in the lowest ppm range have been achieved.

The toxicity of chromium ions was investigated using mammalian cell cultures on impedance sensors as well as physiological in vitro sensor systems. The performance of commercially available systems like the 2500 Analyzing System (Bionas), xCELLigence (Roche) and Cytosensor Microphysiometer (Molecular Devices) was compared with a novel CMOS-based impedance-to-frequency converter device. Cell-based sensor systems are shown to be powerful tools to detect Cr(VI) pollutions within several hours in the range of multinational drinking water regulations. The ability to distinguish between toxic Cr(VI) and non-toxic Cr(III) species is one advantage of these integral sensor systems. Impedance only devices are not sufficient for the fast detection of toxic chromium species as rapid cellular changes occur only in the respiration system and the cell physiology. © 2013 Elsevier B.V. ispartof: Sensors and Actuators B, Chemical vol:182 pages:58-65 status: published

Pollution of drinking water sources represents a continuously emerging problem in global environmental protection. Novel techniques for real-time monitoring of water quality, capable of the detection of unanticipated toxic and bioactive substances, are urgently needed. In this study, the applicability of a cell-based sensor system using selected eukaryotic cell lines for the detection of aquatic pollutants is shown. Readout parameters of the cells were the acidification (metabolism), oxygen consumption (respiration) and impedance (morphology) of the cells. A variety of potential cytotoxic classes of substances (heavy metals, pharmaceuticals, neurotoxins, waste water) was tested with monolayers of L6 cells (rat myoblasts). The cytotoxicity or cellular effects induced by inorganic ions (Ni(2+) and Cu(2+)) can be detected with the metabolic parameters acidification and respiration down to 0.5 mg/L, whereas the detection limit for other substances like nicotine and acetaminophen are rather high, in the range of 0.1 mg/L and 100 mg/L. In a close to application model a real waste water sample shows detectable signals, indicating the existence of cytotoxic substances. The results support the paradigm change from single substance detection to the monitoring of overall toxicity.

Typically, carbon nanotube field effect transistors (CNFETs) based sensors exhibit substantial gate hysteresis and therefore, prior to measurements, require electrical initialization to erase electrical history of their threshold voltage (Vth(t)). Particularly, for CNFET gas sensors, which respond with small Vth shifts to analyte concentration changes, electrical initialization is necessary for reliable sensor operation. Here, we propose and demonstrate electrical initialization of CNFETs for sensing applications by applying triangular ambipolar pulse (TAP) sequences to the gate electrode., Procedia Engineering, 5, Eurosensor XXIV Conference

A laser spectroscopic oxygen sensor aiming at combustion optimization is developed. The sensor allows for self-monitored operation and has a response time of 300 ms. The accuracy for the oxygen concentration is better than ±0.2 vol%. The laser optical sensor is inherently calibration-free and does not age compared to the conventional ZrO2 probes. The spectroscopic oxygen sensor is based on a diffuse reflective geometry, which minimizes possible optical interference and also alignment problems caused by the thermal cycles of the furnace and an efficient evaluation algorithm that allows for long-term stable operation.

A miniaturized optical carbon-monoxide sensor based on tunable diode laser spectroscopy is presented and tested for various applications. It utilizes recently developed Vertical-Cavity Surface-Emitting Lasers (VCSELs) emitting at 2.3 μm as light source and the photodetector housing as integrated gas reference cell. Together with a wide/narrow spectral scan algorithm for wavelength stabilization, a compact, self-monitored and microcontroller-based sensor is realized. In contrast to conventional line-locking, the full wavelength scale of the spectral scans is inherently calibrated. The achieved sensing resolution (1 sigma) is 3 ppm for 1 second averaging.

We investigate the possibility of applying rectangular voltage pulses to the gate electrode of carbon nanotube field effect transistors (CNFETs) for NO2 detection. CNFET gate characteristics measured using pulsed gate voltages show a reduction of hysteresis by about 20% compared to measurements with linearly swept gate voltages. Moreover, an enhancement of the measurement range is observed in the pulsed regime. The characterized CNFET devices are based on individual single-walled carbon nanotubes (SWNTs), which act as the sensing elements.

Simultaneous Hall and conductivity measurements were performed in situ between 650° and 1050°C on n-type semiconducting BaSnO3ceramics. The variation of the Hall mobility and the Hall carrier density as a function of oxygen partial pressure between 102 and 105 Pa and of temperature was investigated. At temperatures below 900°C the conductivity exhibits a dependence on temperature and oxygen partial pressure which is mainly determined by variations of the Hall mobility. Above 900°C most of the significant dependence is due to a variation in carrier density. Furthermore, a simple defect model assuming doubly ionized oxygen vacancies and acceptor impurities is discussed for BaSnO3.

The gas sensitivity of Ga2O3 thin-film n-type conductors was investigated at temperatures of 500–1000°C. Palladium dispersions whose particle sizes are dependent on the preceding annealing processes were deposited by a wet-chemical technique onto Ga2O3 thin-film ceramics. The palladium clusters and their temperature-dependent growth were detected using scanning electron microscopy micrographs and X-ray photoemission spectroscopy measurements. The effect of the palladium dispersions on the gas-sensitive behavior of the Ga2O3 ceramics was investigated in various O2/H2 mixtures in the N2 carrier gas at 700°C. The conductivity of the ceramics treated in this way was dependent on the O2 partial pressure, as well as on the H2 partial pressure of the surrounding gas atmosphere. The ceramic conductivity can be described as a function of the O2:H2 ratio, in accordance with the relation σ(pO2/pH2/)−1/3.

Conventional thimble type lambda sensors show strong response on NOx by evaluation of the open circuit discharge characteristics after defined polarizations with alternating signs. The sensor signal is dependent on oxygen or water concentration but the influence on discharge characteristics is consistent with Nernstian behavior. This confirms the feasibility of a pulsed mode operated lambda probe as a NOx sensor for exhaust gas measurements. To find the underlying mechanism of this polarization technique, the current during the voltage pulse is evaluated in a simulated combustion exhaust gas with varying oxygen and moisture levels. By increasing the oxygen or water content in the exhaust the polarization current decreases at both polarization directions. Platinum oxidation during voltage pulses is assumed to be responsible for this effect.

Switching from fossil based to renewable power generation requires the installation of large overcapacities of wind and solar due to their intermittency. Storage or conversion possibilities are essential due the volatility of electricity. Economic feasibility is difficult when considering the low fossil energy carrier prices and the physical efficiency limitations of the processes. Therefore, we choose to focus on high volume chemical feedstock such as Ethylene or CO, where the chemical value exceeds by far its pure heating value. Electrocatalyts facilitate the conversion of CO2 to valuable base chemical feedstocks – for selectivity improvements substantial advances in electrode design are required. Depending on the electro catalytic system, CO2 can be electrochemically reduced to carbon monoxide (CO), methane (CH4), ethylene (C2H4) and various other hydrocarbons even in aqueous media. CO could be obtained with faradic efficiencies over 90% at current densities exceeding the industrial necessary level of 100 mA/cm² with a total energy efficiency approaching 50%. Ethylene is more challenging due the highly complex reduction process involving 12 electrons and 8 protons. Faradic efficiencies up to 57% for ethylene at current densities above 150 mA/cm² could be obtained using in-situ-deposited nano-structured copper based electrocatalysts. In many experiments we observed a large gap in the sum of the current efficiencies of gaseous products to 100% FE. It is well known, that the electro-reduction of CO2 also yields liquid products. This gap could be fully closed by detailed analysis of the electrolyte revealing a strongly pronounced formation of ethanol (> 20% FE) accompanied by wide range of C1-C3 alcohols, carboxylates and ketones in yields up to ~ 5%. To the best of our knowledge, the here reported faradaic efficiencies for ethanol above 20% in a current density regime above 150mA/cm2 have been unpresent in the literature so far. In addition time resolved parallel analysis of the gaseous and liquid product distribution revealed striking relationships between different species i.e. the parallel formation of ethylene and ethanol. Figure 1

In this study, a cell-based gas biosensor is presented used for the detection and investigation of gaseous organic compounds in air. The response of living human nasal cells (RPMI 2650) and human lung cells (A549) towards the direct exposure of gaseous substances for 10 min is monitored with a multi-parametric sensor system. Changes in the cellular impedance, oxygen consumption rate and acidification rate can be recorded after the exposure and represent the cytotoxicity of the present gas. The sensor is able to notify the presence of acetone in aqueous solution (2%) but in notably lower concentrations in the gas phase (100-333 ppm) within 30-60 min after the end of the gas exposure. Cell viability is not affected by a sequential exposure to humidified synthetic air (60% r.h.) with a flow rate of 300 ml/min and therefore offers the possibility for a continuous air monitoring. In addition, exposure to synthetic air has no influence on the signals of consecutive acetone exposure. The system might be used in the future for the monitoring of ambient air in work spaces. ispartof: Biosensors & Bioelectronics vol:40 issue:1 pages:393-400 ispartof: location:Cancun: MEXICO status: published

In this study, a cell-based gas biosensor is presented, which can be used for the detection of gaseous organic compounds in ambient air. The response of living human nasal cells (RPMI 2650) towards the direct exposure of gaseous substances is monitored with a multi-parametric sensor system using an exposure time of 10-15 minutes. Changes in the cellular impedance, oxygen consumption rate and acidification rate are recorded immediately after the exposure and represent the metabolic cell reaction to the gas presented. The system is able to notify the presence of acetone in aqueous solution (~2%) but also - in significantly lower concentrations - in the gas phase (~200 ppm) within 30 minutes. The concentration-dependent decrease of cellular impedance is caused by the lipophilicity of this solvent, which causes hydrophobic interactions within the protein structure of the cell. The system might be used in the future for the monitoring of ambient air in work spaces as well as for the characterization of medical gases and aerosols.

Simultaneous Hall and conductivity measurements have been performed on sputtered polycrystalline thin films and on bulk ceramic specimens of nearly stoichiometric CeO[sub 2] in the temperature range between 900 and 1,040 C. The measurements have been performed in air using low-frequency alternating current. In the case of the bulk ceramic specimens, an upper limit for the carrier mobility of [le] 0.2 cm[sup 2]/(V[center dot]s) has been obtained, which is in accordance with data from the literature for bulk samples. The conductivity of the thin films is in accordance with data from the literature for bulk ceramics. The carrier density derived from the Hall measurements increases with increasing temperature, whereas the Hall mobility decreases with increasing temperature. These values differ from literature data for bulk ceramic specimens. The difference may be due to the small grain diameters in the 1-[mu]m-thick thin films.

Zusammenfassung Diese dynamische Messmethode mit wechselseitiger Polarisation der Elektroden und Auswertung der Entladekurven bietet den grosen Vorteil, dass an einfachen Sensorelementen Stickoxide in kleinem Konzentrationsbereich detektiert werden konnen. Bei dieser Spannungs-Puls-Methode ist die Form und Lage der Selbstentladekurve charakteristisch fur die Gaskonzentration. Da bei allen Anwendungen der Wassergehalt eine grose Rolle spielt, wurde in dieser Studie dieser Einfluss genauer betrachtet.

The topography of resistive Ga2O3 metal oxide sensing devices was examined and characterized with an atomic force microscope (AFM). The sensing devices do not have to be destroyed for characterization and stay fully functional. Deposition of nobel metal dispersions, for example, palladium (Pd), onto the sensor surface improves its properties by adding catalytic activity. The distribution of the Pd clusters was investigated.

We demonstrate an ultralow sample volume optical carbon monoxide sensor with detection sensitivity of 180 parts in 10(9) (1σ at 1 Hz). The utilization of a 2.3 μm surface-emitting laser directly coupled to a 3 m hollow capillary fiber as the gas cell is proven to be a compact, sensitive, and cost-efficient gas sensing concept. By mechanical vibration of the fiber, an absorbance resolution of 10(-5) is achieved, which is comparable to single-reflective (double-pass) cells. An improvement of sensitivity over the conventional single-reflective cell is thus approximately linearly scaled with the enhancement of the optical path length, which is usually more than 1 order of magnitude.

An ammonia exhaust gas sensor for harsh environments enables to control the NH3 emission downstream an SCR (selective catalytic reduction) catalyst, which is used to reduce the NOx emissions of diesel engines and industrial plants. A novel mixed potential NH3 exhaust gas sensor for selective NH3 detection showed in synthetic exhaust a very good correlation between sensor voltage and NH3 concentration with a marginal NOx cross interference. First tests in real exhaust gas to proof the applicability showed promising results.

The oxidation reaction equilibrium constant and the holes mobility in p-type-semiconducting SrTiO3 single crystals were determined directly by simultaneous Hall and conductivity measurements between 500° and 1000°C. This information and the SrTiO3 defect model were used to interpret the electrical measurements taken on this substance which represents a model substance for semiconducting perovskites. Measurements with varying oxygen partial pressures showed that shifts of the crystal defect equilibrium give rise to changes in the carrier concentration with unchanged carrier mobility.

We present a miniaturized particle sensor collecting scattered light in two solid angle intervals by Fresnel ring lenses. The particle size is determined from the ratio of both scattering amplitudes (intensity ratio) in addition to a linear diversity combining technique, generating a 3D particle size matrix that reduces the ambiguity by the index of refraction on the particle size identification. A signal-to-noise ratio of 30.3 was achieved for 147 nm sized polystyrene latex particles. Measurements of polydisperse particle size distribution show good agreement with the results by a scanning mobility particle sizer.

The authors describe a newly developed motor concept which allows a bidirectional piezoelectric ultrasonic motor to be operated with only a single voltage feed and thus only one power amplifier. The motor concept is based on the superposition of a longitudinal and a flexural oscillation of a rod-shaped resonator. In a way analogous to the generation of a Lissajous figure, this superposition produces a rotary movement of the resonator end by means of which a rotor is directly driven. By selecting the relative phase of the electrical stimulations of both modes, the speed can be continuously varied in both directions. The motor can be driven in both right and left directions with speeds of 0 to 300 r/min, and a freewheeling state can be set up by means of a suitable phase between the oscillation modes. In the off state, the motor blocks the motion. >

We present a measurement approach to obtain increased differentiation of exhaust gas components and stabilized signal behavior using a standard zirconia-based potentiometric lambda probe. The self-discharge characteristic after different voltage pulses applied to the sensor is used as a measured parameter which depends on gas type and concentration. The detection of NO in the lower ppm range is demonstrated. In addition, this approach allows to improve the response and selectivity to NO significantly compared to other investigated gases as NO2, NH3, H2 and a mixture of hydrocarbons. Therefore, this technique seems to be capable to enable NO sensing in exhaust gas with improved selectivity using standard lambda probes.

An ultrasonic piezoelectric motor concept is presented that is based on the transformation of the longitudinal oscillations of a rod-shaped resonator into continuous motion by arranging the resonator diagonally to a drum. The efficiency of the motor was enhanced by increasing the amplitude of motion at the point of motion transfer by tapering the resonator. To optimize the resonator design, the validity of the predictions derived from the one-dimensional analytical theory for longitudinal ultrasonic resonators was tested with respect to this application by means of finite-element calculations. The one-dimensional calculation turned out to be hardly applicable at all to real resonators. The finite-element calculations showed that maximum final amplitude is attained when the resonator tapers as steeply as possible, no preference being shown for any special mathematical form of cross-sectional reduction. Efficiencies of 35% and torques of 25 N-cm were attained at 150 r/min. >

Technological Roadmap Technical Appendix Part 4 - Sustainable Carbon Capture and SUNRISE Key Enablers

Consolidated Vision of the SUNRISE initative:The vision of SUNRISE is to enable the production of renewable fuels, chemicals and materials on a global scale using abundant molecules as feedstocks (e.g., H2O, CO2, N2) and sunlight as the primary energy source.

Technological Roadmap Technical Appendix Part 2 - Sustainable Ammonia Production

Roadmap document for theSUNRISE action, itaims at promoting a large-scale research initiative toprovide short and long-term solutionsto enable the transition to a circular economypowered by sunlightthrough the sustainable production of fuels and chemicals. SUNRISE’s main objective is to facilitate a carbon-neutral society by using abundantly available molecules – carbon dioxide, water and nitrogen – to replace fossil-based raw materials for the production of a broad range of chemicals and fuels. This way, our initiative targets a sustainable CO2 cycle, where the concentration in the atmosphere is decreased and then maintained at a level compatible with climate stability, committing to the sustainable use of natural resources and land.

Technological Roadmap Technical Appendix Part 4 - Sustainable Carbon Capture and SUNRISE Key Enablers

Technological Roadmap Technical Appendix Part 1 - Sustainable Hydrogen Production

Technological Roadmap Technical Appendix Part 3 - Sustainable carbon-based chemicals and (jet)fuels