Search results for "efficiency"
showing 10 items of 1430 documents
Electrochemical conversion of CO2 to formic acid using a Sn based electrode: A critical review on the state-of-the-art technologies and their potenti…
2021
Abstract The electrochemical conversion of carbon dioxide is considered one of the most promising strategies to convert waste-CO2 into value-added chemicals. This review focuses on the synthesis of formic acid/formate in aqueous electrolyte using Sn-based cathodes; this material is considered relatively cheap and shows promising results in terms of faradaic efficiency. In order to be suitable at an industrial scale, the process should present simultaneously high current densities, faradaic efficiencies close to 100%, high concentrations of formic acid and long-term stability. Analysing the main results reported in the literature, it was observed that to date further studies are necessary to…
Fullerene imposed high open-circuit voltage in efficient perovskite based solar cells
2016
Five different commercially available fullerenes are evaluated as hole blocking/electron transporting materials in p–i–n methylammonium lead iodide perovskite solar cells using a vacuum deposited perovskite absorber layer. A significant enhancement of the solar cell performance can be obtained by selecting a suitable fullerene derivative. Open-circuit voltages as high as 1.11 volts are obtained leading to a power conversion efficiency of 14.6%.
Enhanced power-conversion efficiency in organic solar cells incorporating copolymeric phase-separation modulators
2018
A new class of copolymers containing oligothiophene moieties with different lengths and fullerene units have been designed and prepared by an easy and inexpensive one-step synthetic approach. The incorporation of small quantities of these copolymers into bulk heterojunction (BHJ) solar cells with donor regioregular polythiophene (P3HT) and an acceptor fullerene derivate (PCBM) results in good control of the phase separation process without further affecting the BHJ optoelectronic properties. Indeed, under thermal annealing these copolymers allow the modulation of the growth of domains whose size depends on the length of the copolymer repetitive units. Domain size on the same length scale as…
High-pressure synthesis of CO and syngas from CO2 reduction using Ni-N-doped porous carbon electrocatalyst
2022
Abstract Electrochemical conversion of CO2 to CO or syngas (CO/H2 mixture) is considered one of the most promising approaches to valorise waste-CO2. To develop the process on industrial scale, it would be necessary to use selective and inexpensive electrodes and to obtain high productivities with low energy consumption. In this frame, Ni−NC catalysts are considered among the most interesting ones because of their relatively low cost, high faradaic efficiency in CO ( F E C O ), and high stability. However, up to now, quite low productivities were obtained as a result of low current densities achieved in aqueous electrolytes. In this work, we have evaluated the performances of a Ni−NC electro…
Phenothiazine dye featuring encapsulated insulated molecular wire as auxiliary donor for high photovoltage of dye-sensitized solar cells by suppressi…
2019
Abstract Two efficient dye-sensitized solar cells have been fabricated by two novel D–D–π–A phenothiazine-based organic dyes (PH2 and PH3) with an encapsulated insulated molecular wire (EIMW) as an auxiliary donor. The cell sensitized by PH2 with EIMW as an auxiliary donor shows a much higher photovoltage (Voc) relative to the reference dye PH1 without EIMW, because the former dye can inhibit dye aggregation and suppress the charge recombination effectively. The results show that the cell sensitized by PH2 with co-adsorption of chenodeoxycholic acid obtains a high power conversion efficiency, even higher than that of the cell based on N719. Thus, an effective way to increase the photovoltag…
First experimental results of a cryogenic stopping cell with short-lived, heavy uranium fragments produced at 1000 MeV/u
2013
A cryogenic stopping cell (CSC) has been commissioned with U-238 projectile fragments produced at 1000 MeV/u. The spatial isotopic separation in flight was performed with the FRS applying a monoenergetic degrader. For the first time, a stopping cell was operated with exotic nuclei at cryogenic temperatures (70 to 100K). A helium stopping gas density of up to 0.05mg/cm(3) was used, about two times higher than reached before for a stopping cell with RF ion repelling structures. An overall efficiency of up to 15%, a combined ion survival and extraction efficiency of about 50%, and extraction times of 24ms were achieved for heavy a-decaying uranium fragments. Mass spectrometry with a multiple-r…
Electrophoretically deposited α-Fe2O3 and TiO2 composite anchored on rGO with excellent cycle performance as anode for lithium ion batteries
2018
Abstract Two nanostructured oxides, α-Fe2O3 and TiO2 with a particle diameters 50 nm and 21 nm, were mixed with graphene oxide (GO). Composite thin films on a stainless steel substrate were obtained by electrophoretic deposition (EPD) procedure from water suspensions: α-Fe2O3/GO, TiO2/GO and α-Fe2O3/TiO2/GO. Subsequently reduction of as-prepared thin films was performed. Thicknesses of acquired films were evaluated in the range of 2–6 μm. Structure and morphology were investigated as well as electrochemical properties of all samples were studied. The results revealed that α-Fe2O3/TiO2/rGO (in this article denoted as FTGO) exhibited the specific discharge capacity of 790 mAh·g−1 after 150 cy…
Influence of the age of amorphous nonannealed As2S3 thin films on holographic properties
1998
The dependences of the maximal first order diffraction efficiency and the corresponding specific recording energy on the holographic grating period were studied. Grating period was varied from 0.40 to 70.0 μm. Both fresh and aged films were used. A large holographic recording efficiency decrease in the course of aging is found to take place. These changes are due to the effective film grain size increase caused by the relaxational structural changes and atmospheric oxygen exposure. Results are explained with the aid of stress fields induced by the evaporation and holographic recording. The obtained results can be used to optimize the hologram recording in amorphous chalcogenide films.
Two-color holographic-grating formation in amorphous As_2S_3 films
1998
A detailed experimental study of the holographic gratings recorded in nonannealed amorphous As2S3 films by 514.5-nm light in the presence of 632.8-nm readout light is carried out. A strong influence of a continuous 632.8-nm readout is found. The dependences of the maximal first-order diffraction efficiency and the corresponding specific recording energy on the holographic grating period were studied in a wide range of periods from 0.40 to 70.0 μm for 2-yr-old films. The obtained results are discussed in terms of photoinduced structural changes, relaxational structural changes, photoinduced anisotropy, and photoinduced recharging of the localized states in the bandgap. The photoinduced sulph…
External quantum efficiency measurements used to study the stability of differently deposited perovskite solar cells
2020
The instability exhibited by perovskite solar cells when exposed to the environment under illumination is one of the major obstacles for the entry of perovskite technology in the photovoltaic market. In this work, we use the external quantum efficiency (EQE) technique to study the photoinduced degradation of two types of solar cells having CH3NH3PbI3 as an absorber layer: one deposited by spin coating with an n-i-p architecture and the other deposited by evaporation with an inverted p-i-n structure. We also study the effect of different encapsulants to protect the cells against atmospheric agents. We find that EQE provides information regarding the areas of the cell most susceptible to degr…