Materials for Renewable and Sustainable Energy最新文献

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.

Proton exchange membrane fuel cells (PEMFC) play a key role for sustainable energy; however, catalyst degradation remains one of the main challenges for competing with traditional energy technologies. The Pt/C commercially available electrocatalysts are susceptible to Pt dissolution and carbon support corrosion. In this context, we design a Pt–NbO_x catalyst supported on TiN nanoparticles as an alternative electrocatalyst for the oxygen reduction reaction (ORR). The use of Pt–NbO_x reduces materials’ costs by lowering the required platinum loading and improving catalyst performance. The TiN support is selected to improve support stability. The electrocatalyst is successfully synthesized by a one-step flame spray process called reactive spray deposition technology. Electrocatalyst with two different very low Pt loadings (0.032?mg?cm^?2 and 0.077?mg?cm^?2) are investigated and their performance as cathode is evaluated by the rotating disk electrode method. The new electrocatalyst based on Pt–NbO_x supported on TiN has ORR performance that is comparable to the state-of-the-art Pt/C electrocatalyst. A half-wave potential of 910?mV was observed in the polarization curves, as well as a mass activity of 0.120 A?mg_Pt^?1 and a specific activity of 283 μA?cm_Pt^?2 at 0.9?V. These results demonstrate that Pt–NbO_x on TiN electrocatalyst has the potential for replacing Pt/C cathode in PEMFC.

This article evaluates the thermal and energy performance of mortar blocks?containing?local agricultural waste. The mortar blocks were cast by the replacement of ordinary Portland cement (OPC) with varying amounts of date palm ash (DPA) in the range of 10–30%. Experiments and simulations were carried out to assess the thermal characteristics and energy performance of the specimens. A prototype office building was modeled and simulated in DesignBuilder (Version 6.1.06) with modified blocks prepared with DPA under the Arabian Gulf environment characterized by hot and humid climatic conditions of Dhahran, Saudi Arabia.?The developed blocks are characterized as lightweight blocks based on density data which satisfy the requirement of ASTM C55-11. The analysis and simulation indicate that the incorporation of DPA improves the thermal resistance of up to 47%, enhances the indoor environment?and yields annual energy consumption of up to 7.6%, consequently reduces the cost of masonry block production by?~?11% without compromising the physical, chemical, and mechanical properties. The masonry blocks prepared with DPA found to be economical than conventional masonry blocks. It is postulated that the novel DPA-based developed blocks are significantly sustainable products which will contribute to the?valorization of DPA waste along with the reduction in the cost of construction and operational cost of the building.