Materials for Renewable and Sustainable Energy最新文献

Herein, copper oxide/copper sulfide (CuO/Cu_xS) composites have been prepared by treating CuO with thiourea by an aqueous hydrothermal route and their thermoelectric properties are studied. The electrical conductivity is improved with the increase in thiourea content, as a result, thermoelectric power factor increased from 10^–4 to 10¹?μW?m^?1?K^?2, and thermal conductivity of the CuO is also found to decrease with thiourea treatment. A detailed analysis indicated that these changes are due to the formation of copper sulfide (Cu_xS) in the CuO compound; a small fraction of electrically good conducting Cu_xS in the bulk CuO has produced composites with better electrical conductivity. These low-cost and non-toxic materials can be useful in thermoelectric energy conversion applications.

In this work new naphthalenediimides (NDIs) were synthesized and used as dyes in DSSC. The efficiency (η) of the DSSC is influenced by NDIs electronic and structural characteristics. It was found a better cell performance with the NDIs which have a broader absorption band shifted to the red color, high ? values, and more adsorption in the anode surface. The band gaps were determinate by UV–vis and cyclic voltammetry. The LUMO orbitals of most of the NDIs are above of the conduction band (CB) energy for TiO₂ allowing the electron transfer process from the NDI to the photoanode, especially in those with a significant LUMO^NDI-CB^Ti energetic difference. Also, NDIs with polar groups in their structure presented higher η values due to a better adsorption on the photoanode surface, which allows a better energy capture compared with those with lower adsorption.

The lithium–sulfur (Li–S) batteries are promising because of the high energy density, low cost, and natural abundance of sulfur material. Li–S batteries have suffered from severe capacity fading and poor cyclability, resulting in low sulfur utilization. Herein, S-DHCS/CNTs are synthesized by integration of a double-hollow carbon sphere (DHCS) with carbon nanotubes (CNTs), and the addition of sulfur in DHCS by melt impregnations. The proposed S-DHCS/CNTs can effectively confine sulfur and physically suppress the diffusion of polysulfides within the double-hollow structures. CNTs act as a conductive agent. S-DHCS/CNTs maintain the volume variations and accommodate high sulfur content 73?wt%. The designed S-DHCS/CNTs electrode with high sulfur loading (3.3?mg?cm^?2) and high areal capacity (5.6?mAh?mg?cm^?2) shows a high initial specific capacity of 1709?mAh?g^?1 and maintains a reversible capacity of 730?mAh?g^?1 after 48 cycles at 0.2 C with high coulombic efficiency (100%). This work offers a fascinating strategy to design carbon-based material for high-performance lithium–sulfur batteries.

This study reports the performance analysis of an organic dye-sensitized solar cell (DSSC), introducing MnO₂ as an electron transport layer in TiO₂/MnO₂ bilayer assembly. The DSSCs have been fabricated using TiO₂ and TiO₂/MnO₂ layer-by-layer architecture films onto fluorine-doped tin oxide (FTO) glass and sensitized with natural dye extracted from Malvaviscus penduliflorus flower in ethanol medium. The counter electrode was prepared to layer copper powder containing paste onto FTO's conductive side by the doctor's blade method. The optical, morphological, and structural properties of photoanodes were explored via ultraviolet–visible, field emission scanning electron microscopy, and X-ray diffraction analyses. Moreover, dye complexity and thermostability of dyes were characterized via Fourier-transform infrared spectroscopy and thermogravimetric analyses. The iodide/triiodide (i.e., I^?/I₃^?) redox couple of electrolyte solution was employed as a charge transport medium between the electrodes. Finally, photoanode and counter electrode sandwiches were assembled to envisage the photovoltaic performance potential under simulated AM 1.5G solar illumination using 100 mW cm^–2 light intensity. The as-fabricated DSSC comprising TiO₂/MnO₂ bilayer assembly exhibited 6.02?mA?cm^–2 short circuit current density (J_sc), 0.38?V open-circuit voltage (V_oc), 40.38% fill factor, and 0.92% conversion efficiency, which is about 200% higher compared to the assembly devoid of MnO₂ layer.

Two of the important aspects for the successful utilization of phase change materials (PCMs) for thermal energy storage systems are compatibility with container materials and stability. Therefore, the present study is focused on testing the corrosion resistance and surface characteristics of metals in contact with PCMs and thermal behavior of PCMs with heating/cooling cycles. The PCM selection is made by targeting low temperature (<100?°C) heat storage applications. The PCMs considered are paraffin wax, sodium acetate tri-hydrate, lauric acid, myristic acid, palmitic acid, and stearic acid. The metal specimens tested are aluminum, copper, and stainless steel because of their wide usage in thermal equipment. The tests are performed by the method of immersion corrosion test, and ASTM G1 standards are followed. The experiments are carried out at 80?°C and room temperature (30?°C) for the duration of 10, 30, and 60?days. Pertaining to thermal stability 1500 melting/freezing cycles are performed. Investigation has been carried out in terms of corrosion rate, SEM analysis of metal specimens, appearance of PCMs, and variation of thermophysical properties at 0th, 1000th, and 1500th thermal cycles. The most affected area of corrosion, including the dimension of pits, is presented, and comparison is made. Based on the corrosion experiments, recommendations are made for the metal–PCM pairs. Pure sodium acetate trihydrate is observed to suffer from phase segregation and supercooling. After 1500 thermal cycles, the variation in melting and freezing point temperatures for rest of the five PCMs are in the range of ??1.63 to 1.57?°C and ??4.01 to 2.66?°C. Whereas, reduction in latent heat of melting and freezing are in the range of 17.6–28.95% and 15.2–26.78%.

Dye-sensitized solar cells (DSSCs) are under extensive research works due to their appealing features such as low production costs. The production costs and energy conversion efficiency of DSSCs is strongly influenced by the types of dyes used to harvest photons. Natural dyes extracted from different sources are emerged as a potential candidates to synthetic photosensitizers due to their merit properties including low cost, complete biodegradability, availability and less environmental concern. In order to improve the energy conversion efficiency of natural photosensitizers, blending of different dyes, co-pigmentation of dyes, acidifying of dyes and other approaches have been conducted by researchers, resulting in appreciable performance. This paper reviews the factors affecting the stability of anthocyanin pigments and also the solvents needed for efficient extraction of anthocyanins. Moreover, the potential application of anthocyanin dyes as photosensitizers for DSSC along with the work done over the years is covered.

MoS₂-deposited TiO₂ hollow spheres were synthesized successfully under mild temperature and autogenous pressure. The hydrothermal technique was adopted for the synthesis of the TiO₂ hollow microsphere, followed by a photodeposition technique for the deposition of MoS₂. The physical and chemical nature of the samples was characterized using X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, photoluminescence spectroscopy, XPS and UV–vis spectroscopy. In an aqueous medium under the influence of light, the characterized samples were used in the production of hydrogen via photocatalysis. The increase in the formation of hydrogen content during photocatalysis confirms the successful generation and the benefits of the photogenerated carriers. With an increase in the MoS₂ content, there is an incredible change in the photocatalytic performance. The resultant is due to the free moment of the holes and electrons and lessening in charge recombination centres formed as a result of the nano-heterojunction linking between MoS₂ and TiO₂. A more significant photocatalytic production of hydrogen was achieved using 50 MST sample i.e. 106?μmol^?1?g^?1 beyond which it tends to decrease with an increase in MoS₂ content.

Nickel nanoparticles supported by commercial carbon paper (CP) are prepared by pulsed laser deposition with deposition time of 3, 6, and 12?min as a catalyst for urea electro-oxidation. The surface conditions and the morphologies of the prepared electrodes have been characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Urea electro-oxidation reaction in KOH solution on the Ni/CP electrodes is investigated by cyclic voltammetry and chronoamperometry. The results show that the electrode with less Ni nanoparticle agglomeration shows higher peak current density, which was achieved in the 3?min deposition samples when normalized by electroactive surface areas. However, the highest current normalized by the area of the carbon paper was achieved in the 6?min deposition sample due to the larger quantity of Ni nanoparticles. All the samples show good stability. Our results suggest that the low density, low cost, and environmental friendly CP can be used as support for Ni nanoparticle as a catalyst for urea electro-oxidation. It thus has great potential for many applications involving urea oxidation, such as wastewater treatments.

Electrodeposition is one of the leading non-vacuum techniques for the fabrication of CuInSe₂ (CIS)-based solar cells. In the present work, pulse electrodeposition, an advanced technique, is utilized effectively for CIS absorber preparation devoid of any additives/complexing?agents. An economic pulse electrodeposition is employed for the deposition of Cu/In stack followed by selenization to fabricate CIS absorbers on flexible and glass substrates. The approach uses a two-electrode system suitable for large area deposition and utilizes the fundamentals of pulse electrodeposition with appropriate optimization of parameters to obtain smooth Cu/In precursors. The selenized CIS absorbers are of 1?μm thick while possessing copper-poor composition (Cu/In ≈ 0.9) and tetragonal chalcopyrite phase. The fabricated devices have exhibited a power conversion efficiency of 5.2%. The technique can be further improved to obtain low-cost CIS solar cells which are suitable for various small-scale energy applications.