Highly efficient solution processed nanorice structured NiS counter electrode for quantum dot sensitized solar cells

Propyl paraben removal using Cu2O/ZnO-NPs photocatalyst elaborated via green method

The aim of the present work is to investigate the photocatalytic degradation of propyl paraben (propyl para-hydroxybenzoate, PrP) using Cu2O-ZnO-NPs photocatalyst followed by the identification of the oxidation by-products. The Cu2O-ZnO-NPs material, synthesized using a green chemistry approach, was used as a photocatalyst for the removal of PrP. The nanoparticles were characterized by XRD, XRF, diffuse reflectance spectroscopy, ATG/DTG, FTIR, SEM-EDX, BET and FRX techniques. The XRD results showed that Cu2O-ZnO-NPs have a nanometer size of 24.13 nm. The DR-UV analysis showed that Cu2O-ZnO-NPs has an Eg of 2.35 eV which corresponds to the absorption of visible light. The SEM-EDX analysis showed that the ZnO has a hexagonal structure while the CuO has a monoclinic structure. The effect of variables such as propyl paraben concentration (PrP), hydrogen peroxide concentration (H2O2), catalyst dose, and the reaction temperature on the pseudo-first order reaction rate constant (kapp) of the reaction was evaluated. It was found that the degradation of PrP was governed by hydroxyl radical °OH attack and the pathways consisted of a cascade of reactions. The optimum photocatalytic degradation was obtained with an initial catalyst dose of 50 mg, pH 7, and PrP concentration of 10 mg/L. When the photocatalyst was irradiated, a significant PrP degradation was observed after 30 min of irradiation. The results suggest that Cu2O-ZnO-NPs act as a good photocatalyst for PrP degradation under visible light.

Improving the Conversion Ratio of QDSCs via the Passivation Effects of NiS

To revolutionize the photochemical efficiency of quantum dots sensitized solar cells (QDSSCs) devices, herein, a passivation of the cells with multilayer material has been developed for heterojunctions TiO2/NiS/MnS/HI-30/Pt devices. In this study, NiS and MnS were deposited on a photoanode for the first time as passivated photon absorbers at room temperature. The adoption of NiS as a passisvative layer could tailor the active surface area and improve the photochemical properties of the newly modified cells. The vibrational shifts obtained from the Raman spectra imply that the energy change is influenced by the surface effect, giving rise to better electronic conductivity. The electrochemical stability and durability test for the N/M-3 device slows down and remains at 8.88% of its initial current after 3500 s, as compared to the N/M-1 device at 7.20%. The disparity in charge recombination implies that both the outer and inner parts of the nanoporous material are involved in the photogeneration reaction. The hybridized N/M-3 cell device reveals the highest current density with a low potential onset, indicating that power conversion occurs more easily because photons tend to be adsorbed easily on the surface of the MnS. The Nyquist plot for N/M-1 and N/M-3 promotes the faster transport of electrolytic ions across the TiO2/NiS/MnS, providing a good interaction for the electrolyte. The I-J Value of 9.94% shows that the passivation with the NiS layer promotes electron transport and enhances the performance of the modified cells. The passivation of the TiO2 layer with NiS attains a better power conversion efficiency among the scant studies so far on the surface passivation of QDSCs.

Massively synthesizable nickel-doped 1T-MoS2 nanosheet catalyst as an efficient tri-functional catalyst

In this study, a nickel (Ni)-doped 1T-MoS₂ catalyst, an efficient tri-functional hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) catalyst, was massively synthesized at high pressure (over 15 bar). The morphology, crystal structure, and chemical and optical properties of the Ni-doped 1T-MoS₂ nanosheet catalyst were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ring rotating disk electrodes (RRDE), and the OER/ORR properties were characterized using lithium-air cells. Our results confirmed that highly pure, uniform, monolayer Ni-doped 1T-MoS₂ can be successfully prepared. The as-prepared catalysts exhibited excellent electrocatalytic activity for OER, HER, and ORR owing to the enhanced basal plane activity of Ni doping and formidable active edge sites resulting from the phase transition to a highly crystalline 1T structure from 2H and amorphous MoS₂. Therefore, our study provides a massive and straightforward strategy to produce tri-functional catalysts.

Facile Synthesis of Nanoporous NiS Film with Inverse Opal Structure as Efficient Counter Electrode for DSSCs

To satisfy the high requirement of catalytic activity for efficient dye-sensitized solar cells (DSSCs), a novel nanoporous NiS film with inverse opal structure and outstanding electrocatalytic properties was prepared by a facile template-assisted electrodeposition method. The inverse opal structure makes the film have a larger specific surface area and more catalytic sites, thereby result to a higher electrocatalytic activity. Compared with the flat NiS/FTO electrode, this kind of nanoporous NiS film with inverse opal structure has higher catalytic activity and can be used as a cheap and efficient Pt-free electrode to replace the traditional Pt/FTO electrode. It is of great significance to reduce the cost and promote the wide application of DSSCs. This study opens up a new experimental exploration for further improving the catalytic activity of NiS electrode and the according photovoltaic efficiency of DSSCs. The template-assisted electrodeposition method proposed in this work provides a facile method for morphology control and an easy to be realized way to optimize the catalytic performance of the metal sulfides counter electrode.

ZnS/SiO2 Passivation Layer for High-Performance of TiO2/CuInS2 Quantum Dot Sensitized Solar Cells

Suppressing the charge recombination at the interface of photoanode/electrolyte is the crucial way to improve the quantum dot sensitized solar cells (QDSSCs) performance. In this scenario, ZnS/SiO2 blocking layer was deposited on TiO2/CuInS2 QDs to inhibit the charge recombination at photoanode/electrolyte interface. As a result, the TiO2/CuInS2/ZnS/SiO2 based QDSSCs delivers a power conversion efficiency (η) value of 4.63%, which is much higher than the TiO2/CuInS2 (2.15%) and TiO2/CuInS2/ZnS (3.23%) based QDSSCs. Impedance spectroscopy and open circuit voltage decay analyses indicate that ZnS/SiO2 passivation layer on TiO2/CuInS2 suppress the charge recombination at the interface of photoanode/electrolyte and enhance the electron lifetime.

Quantum dot-sensitized solar cells

A comprehensive overview of the development of quantum dot-sensitized solar cells (QDSCs) is presented.

Phase transformations of novel CuxS nanostructures as highly efficient counter electrodes for stable and reproducible quantum dot-sensitized solar cells

A quantum dot-sensitized solar cell assembled with a Cu_1.12S nanosphere counter electrode exhibited a high power conversion efficiency of 5.88%.

Improving the performance of quantum dot sensitized solar cells through CdNiS quantum dots with reduced recombination and enhanced electron lifetime

Ni²⁺ doped CdS QDs in QDSSCs can suppress charge recombination, prolong the electron lifetime and improve the PCE of the cell.

The effect of TiO2 nanoflowers as a compact layer for CdS quantum-dot sensitized solar cells with improved performance

Currently, TiO2 on a fluorine-doped tin oxide substrate is the most commonly used type of photoelectrode in high-efficiency quantum dot-sensitized solar cells (QDSSCs). The power conversion efficiency (PCE) of TiO2 photoelectrodes is limited because of higher charge recombination and lower QD loading on the TiO2 film. This article describes the effect of a TiO2 compact layer on a TiO2 film to enhance the performance of QDSSCs. TiO2 nanoparticles were coated on an FTO substrate by the doctor-blade method and then the TiO2 compact layer was successfully fabricated on the surface of the nanoparticles by a simple hydrothermal method. QDSSCs were made using these films as photoelectrodes with NiS counter electrodes. Under one sun illumination (AM 1.5 G, 100 mW cm(-2)), the QDSSCs showed PCEs of 2.19 and 2.93% for TCL1 and TCL2 based photoelectrodes, which are higher than the 1.33% value obtained with bare TiO2. The compact-layer-coated film electrodes provide a lower charge-transfer resistance and higher light harvesting. The compact layer on the TiO2 film is a more efficient photocatalyst than pure TiO2 film and physically separates the injected electrons in the TiO2 from the positively charged CdS QD/electrolyte.

Reactively sputtered nickel nitride as electrocatalytic counter electrode for dye- and quantum dot-sensitized solar cells

Nickel nitride electrodes were prepared by reactive sputtering of nickel under a N2 atmosphere at room temperature for application in mesoscopic dye- or quantum dot- sensitized solar cells. This facile and reliable method led to the formation of a Ni2N film with a cauliflower-like nanostructure and tetrahedral crystal lattice. The prepared nickel nitride electrodes exhibited an excellent chemical stability toward both iodide and polysulfide redox electrolytes. Compared to conventional Pt electrodes, the nickel nitride electrodes showed an inferior electrocatalytic activity for the iodide redox electrolyte; however, it displayed a considerably superior electrocatalytic activity for the polysulfide redox electrolyte. As a result, compared to dye-sensitized solar cells (DSCs), with a conversion efficiency (η) = 7.62%, and CdSe-based quantum dot-sensitized solar cells (QDSCs, η = 2.01%) employing Pt counter electrodes (CEs), the nickel nitride CEs exhibited a lower conversion efficiency (η = 3.75%) when applied to DSCs, but an enhanced conversion efficiency (η = 2.80%) when applied to CdSe-based QDSCs.

One-step synthesis of solution processed time-dependent highly efficient and stable PbS counter electrodes for quantum dot-sensitized solar cells

A QDSSC with time-dependent optimized PbS CE exhibits a higherηof 4.61% than that of Pt CE (1.34%).

Cadmium selenide quantum dots solar cells featuring nickel sulfide/polyaniline as efficient counter electrode provide 4.15% efficiency

Much higher photovoltaic performance of QDSSC with CdSe QDs and NiS/PANI counter electrode.

Solution-processed morphology-controllable nanosphere structured highly efficient and stable nickel sulfide counter electrodes for dye- and quantum dot-sensitized solar cells

The DSSC and QDSSC based on as-prepared NiS CE at 0.8 M urea produce a PCE of 5.75% and 3.37%.

The synthesis and characterization of lead sulfide with cube-like structure as a counter electrode in the presence of urea using a hydrothermal method

PbS counter electrodes at different concentrations of urea.

Chemical bath deposition of Cu2O quantum dots onto ZnO nanorod arrays for application in photovoltaic devices

A protective CuO layer on the Cu₂O quantum dots was prepared by simply heat-treating the Cu₂O/ZnO hetero-nanorod arrays in ambient air, which enhances the photovoltaic stability.

A strategy to improve the energy conversion efficiency and stability of quantum dot-sensitized solar cells using manganese-doped cadmium sulfide quantum dots

Better stability and higher performance of Mn-doped CdS QDSSCs (PCE = 2.85%) than those of CdS QDSSCs (PCE = 2.11%).