• Energy Research
• 2016-2025close
• nano-technology close

Due to their high surface areas and large pore volumes, porous carbons (PCs) are valuable materials for use as electrodes in energy storage and conversion devices. Biomass is an ideal precursor for the preparation of PCs in part because it is sustainable and eco-friendly. Herein, new methodology for converting agarose, a naturally occurring type of biomass that forms robust hydrogels, into PCs with tunable pore structures and high electrochemical performance is described. The synthetic process is straightforward and entails heating a gel that is composed of agarose and potassium oxalate (K 2 C 2 O 4 ). Since the salt transforms into gaseous byproducts at elevated temperatures, the decomposition process was harnessed to create activated, open pores as the hydrogel underwent carbonization. For example, a PC with a surface area of 1754.9 m 2 g –1 and a pore volume of 2.643 cm 3 g –1 was obtained by heating a mixture of agarose and K 2 C 2 O 4 in a 1:3 weight ratio at 700 °C. The material was subsequently used as the electrode material in a supercapacitor and found to display a specific capacitance of 166.0 F g –1 at 0.125 A g –1 . Varying the quantity of added K 2 C 2 O 4 resulted in predictable changes in porosity and thus offered a means to tune the textural properties and the electrochemical performance of the PCs. For example, changing the feed ratio of agarose to K 2 C 2 O 4 to 1:6 afforded a PC that exhibited a high persistent specific capacitance (64.1 F g –1 at 5 A g –1 after 10,000 cycles) and a high-power density (20 kW kg –1 at 10 A g –1 ).

Abstract Thin-film silicon tandem (MICROMORPH™) module design optimization process for performance maximization is described together with an analysis of some key reliability topics. In the first part, the procedure for module layout optimization to achieve the maximum module power output is described. In monolithic thin-film modules the layout is realized through a laser scribing interconnection process: a well-controlled laser scribing process is therefore essential to ensure optimal module performance and to minimize unwanted losses. The second part of the paper focuses on some of the materials used in the fabrication of a solar cell and module of such technology and the processes used to achieve such module assembly, as well as a description of some of the possible failure modes. Special attention is paid to the zinc oxide transparent conductive oxide (ZnO TCO) layers used for the front and back contacts. The bottom cell (BoCe) and its stability is also analyzed in detail: the influence of process parameters on the BoCe degradation behavior including the differences observed using different thin-film silicon (TF-Si) deposition reactor types, different lamination foils and the impact using different front contact haze is discussed. In the final part of the paper the effect of particle contamination on the module performance is reviewed: specifically contamination by particles generated during deposition and handling processes. Finally relevant countermeasures to prevent additional module performance loss are discussed.

Abstract An alkaline earth boro-aluminosilicate glass (Eagle XG), a soda-lime glass, and a light-weight polyethylene-terephthalate (PET) foil, used as typical substrates for photovoltaics, were treated by an energetic proton beam (3 MeV, dose 106–107 Gy) corresponding to approx. 30 years of operation at low Earth orbit. Properties of the irradiated substrates were characterized by atomic force microscopy, optical absorption, optical diffuse reflectance, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and terahertz (THz) spectroscopy. Minimal changes of optical and morphological properties are detected on the bare Eagle XG glass, whereas the bare PET foil exhibits pronounced increase in optical absorption, generation of photoluminescence, as well as mechanical bending. On the other hand, the identical substrates coated with Indium-tin-oxide (ITO), which is a typical material for transparent electrodes in photovoltaics, exhibit significantly higher resistance to the modifications by protons while ITO structural and electronic properties remain unchanged. The experimental results are discussed considering a potential application of these materials for missions in space.

Highly efficient nanocatalysts which can selectively decompose hydrous hydrazine for hydrogen production are introduced.

Abstract Previous works indicated that aluminum hydroxide could act as catalyst to assist the hydrolysis reaction of Al, but the catalytic activity of commercial aluminum hydroxide was very poor. In the present research, an AlOOH catalyst with high activity and excellent stability is synthesized using hydrothermal method, and the catalytic effect of this AlOOH catalyst on Al hydrolysis is researched systematically. The results show that AlOOH not only significantly shortens the induction time but also accelerates Al hydrolysis, and the catalytic activity of AlOOH depends on its preparation conditions. The SEM and XRD analyses reveal that the hydrothermal temperature and hydrothermal time have great influence on the crystallinity and grain size of AlOOH, which in turn impact the catalytic activity of AlOOH. The AlOOH catalyst prepared at the hydrothermal temperature of 165 °C for 24 h has the best activity, and it shortens the induction time from 5.00 h to 0.58 h. This work provides a novel and feasible way to generate hydrogen for portable devices.

Developing high capacity yet stable cathodes is key to advancing Li-ion battery technologies. Now, a new metal oxide cathode that is rich in Li with a gradient in Li concentration is shown to be stable to O2 release leading to long cycle life and high capacity.

Of the available environmentally friendly energy storage devices, supercapacitors are the most promising because of their high energy density, ultra-fast charging-discharging rate, outstanding cycle life, cost-effectiveness, and safety. In this work, nanoporous carbon materials were prepared by applying zinc chloride activation of lotus seed powder from 600 °C to 1000 °C and the electrochemical energy storage (supercapacitance) of the resulting materials in aqueous electrolyte (1M H2SO4) are reported. Lotus seed-derived activated carbon materials display hierarchically porous structures comprised of micropore and mesopore architectures, and exhibited excellent supercapacitance performances. The specific surface areas and pore volumes were found in the ranges 1103.0–1316.7 m2 g−1 and 0.741–0.887 cm3 g−1, respectively. The specific capacitance of the optimum sample was ca. 317.5 F g−1 at 5 mV s−1 and 272.9 F g−1 at 1 A g−1 accompanied by high capacitance retention of 70.49% at a high potential sweep rate of 500 mV s−1. The electrode also showed good rate capability of 52.1% upon increasing current density from 1 to 50 A g−1 with exceptional cyclic stability of 99.2% after 10,000 cycles demonstrating the excellent prospects for agricultural waste stuffs, such as lotus seed, in the production of the high performance porous carbon materials required for supercapacitor applications.

AbstractConcrete is a valuable construction material with high mechanical strength and durability, used extensively in the construction industry. It is produced by mixing sand, stones, cement, and water in different proportions depending on the desired quality of the final product. Water reducers are additional chemical ingredients used in concrete to reduce the quantity of water required in the concrete mixture. When added to concrete, water reducers increase the workability and flowability of concrete in the freshly mixed state and improve the mechanical strength and durability of the final hardened product. This review paper describes the different types and applications of concrete water reducers used in the construction industry including their working mechanisms and fluidity effects on concrete properties. It discusses the production of synthetic and bio‐based concrete water reducers and reviews the present challenges involved in the preparation of bio‐based concrete water reducers from renewable resources. © 2023 Society of Industrial Chemistry and John Wiley & Sons Ltd.