Materials for Renewable and Sustainable Energy

Abstract Developing supercapacitor materials that are both efficient and durable, with high cycle life and specific energy, poses a significant challenge due to issues in electrodes such as volume expansion and electrode degradation that occur over time. This work reports a simple, novel, and cost-effective synthesis method to fabricate high surface area “Iron (Fe) doped TiO2 materials” via the metal-organic framework (MOF) route for supercapacitor application. Morphological analysis revealed a disc-like shaped pattern for pristine TiO2 (PT), and a cuboid form for Fe-doped TiO2 (FeT). The electrochemical investigation of MOF-derived PT and FeT electrode materials demonstrated the superior performance of FeT. Cyclic Voltammetry revealed enhanced electrochemical properties in FeT. Galvanostatic charge-discharge measurements confirmed FeT’s higher energy storage capacity, reaching a maximum specific capacitance of 925 Fg− 1. Long-term cycling tests exhibited excellent stability, with FeT retaining 67% of its initial capacitance after 6000 cycles and showing prolonged self-discharge. Overall, the results underscore the potential of Fe-doped TiO2 for high-performance supercapacitors.

Abstract Using the renewable energy, especially solar energy, is an environmental-friendly approach for seawater desalination. Solar evaporation is a promising freshwater harvesting strategy rich in energy, including solar and water energy. Herein, we propose a solar evaporation hybrid hydrogel including polyvinyl alcohol (PVA) and glutaraldehyde (GA) as a polymer network, semiconductor oxide nanoparticles (ZnO, CuO) and activated carbon as a photothermal material. Structural properties of hybrid hydrogel were characterized by X-ray diffraction (XRD) analysis, surface morphology by field emission scanning electron microscope (FE-SEM), chemical bonding by Fourier transform infrared spectroscopy (FTIR) and optical absorption and absorption coefficient (α) of components by UV–Vis spectroscopy. The result showed in visible region, PVA:ZnO:AC hydrogel nanocomposite has a strong absorption (55%) compare of the PVA:CuO:AC hydrogel nanocomposite (35%). In addition, by distillation measurements, the evaporator system demonstrated for PVA:CuO:AC and PVA:ZnO:AC Hydrogel an evaporation rate of 2.29 kg m−2 h−1 and 5.19 kg m−2 h−1 with the evaporation efficiency of 30.66% and 70.80%, respectively, under 0.1 sun irradiation. For PVA:CuO:AC hydrogel, the hardness of Caspian seawater decreased from 6648 to 115 ppm and ion conductance from 8641 (μS) to 244 (μS) and for the PVA:ZnO:AC Hydrogel decreased to 97 ppm and ion conductance to 206 (μS). Experiments showed that with changing type of the ZnO or CuO semiconductor oxide nanoparticles can effectively on regulate the optical properties of the evaporator. Eventually, this work begins a new point of synthesizing cost-effective photothermal absorbers based on metal oxides material and activated carbon nanocomposite.

Abstract The energy consumption for cooling takes up 50% of all the consumed final energy in Europe, which still highly depends on the utilization of fossil fuels. Thus, it is required to propose and develop new technologies for cooling driven by renewable energy. Also, thermal energy storage is an emerging technology to relocate intermittent low-grade heat source, like solar thermal energy and industrial waste heat as well as to exploit off-peak electricity, for cooling applications. This review aims to summarize the recent advances in thermally driven cooling and cold storage technologies, focusing on the formation and fabrication of adopted composites materials, including sorption materials, phase change materials, and slurries. Herein, first the classifications, selection criteria, and properties for these three types of materials is discussed. Then, the application potentials of all the materials are prospected in terms of economic analysis and sustainability.

Abstract Extending the operation of proton exchange membrane fuel cells (PEMFCs) at high temperature (i.e., 120 °C) and/or low relative humidity (< 50% RH) remains a significant challenge due to dehydration and subsequent performance failure of the Nafion electrolyte. We approached this problem by integrating the Nafion matrix with a novel hybrid nanofiller, created through direct growth of TiO2 nanoparticles on the surface of carbon nanotubes. This synthetic approach allowed to preserve an effective nanodispersion of Titania particles in the hosting matrix, thereby boosting dimensional stability, hydrophilicity, and physiochemical properties of the Nafion/MWCNTs-TiO2 (NMT-x) nanocomposites compared to parental Nafion. At optimal concentration (i.e., 3 wt% with respect to the polymer), the nanocomposite membrane exhibited high transport characteristics with impressive water retention capabilities, resulting in a proton conductivity of 8.3 mS cm− 1 at 80 °C and 20% RH. The Titania nanoparticles plays a key role in retaining water molecules even under dehydrating conditions, while also directly contributing to proton transport. Additionally, the long carbon nanotubes promote the formation of additional paths for proton conductivity. These combined features enabled the NMT-3 membrane to achieve a maximum power output of 307.7 mW/cm2 in a single H2/air fuel cell (5 cm2 active electrode area and 0.5 mg Pt/cm2 at both electrodes) under very challenging conditions, specifically at 120 °C and 30% RH. This represents a significant advancement towards overcoming the limitations of traditional Nafion membranes and opens up new possibilities for high-temperature, low-humidity H2/air fuel cell applications.