Central Glass and Ceramic Research Institute

Abstract Bonding agents are a ubiquitous component of monolithic castable refractories that bind the refractory phases under service conditions and provide adequate drying, placement, and corrosion characteristics during application. A wide range of binders have been developed for monolithic castable refractories, ranging from established formulations to commercial products. Persistent effort in the development of these binders is aimed at tuning the properties of these bonding agents with respect to their particle size, chemistry, and other characteristics to get the desired packing, flow, drying, and sintering characteristics for various industrial applications. This paper is dedicated to a comprehensive review of various colloidal binders used as a bonding agent and their significant role in the development of desired properties for monolithic castable refractories. This paper classifies the bonding systems and discusses different colloidal binders, their colloidal chemistry, and their effect on the monolithic refractory castable systems, along with their merits and limitations, followed by concluding remarks and future prospects.

Fuel Cells are the most interesting and updated technology which are renewable energy conversion devices and are Carnot cycle independent. Among various technical design aspects of fuel cells, Solid oxide fuel cells are of prime importance in having highest power efficiency and multi fuel capability. It is capable of amalgamating with intermittent renewable sources like wind, solar etc. as per the geographical feasibility to sustain the overall usable energy demand. Being controlled by electrochemistry, the rate determining process involves simultaneous reactions involving meta stable adsorbed species of oxygen and fuel gases on the electrode catalyst surface. In this context, selection of electrode and tailoring its morphology is important and critical to optimize for maximizing the output and endurability of SOFC. The interfacial regions among electrolyte and electrode are important and forms the primary sites for redox reactions. As per the selection of electrodes, these active sites are termed as triple phase (3PB) or double phase (2PB) which controls electrochemistry at interface and controls the long term tunability of the parent system. The role of morphology of the electrode and the electrolyte interface is therefore crucial. Being an example of all solid conversion devices, the primary catalyst viz transitions metals ions are combined with ceramic counterpart (which forms the electrolyte for selective ion transport) to match the thermal compatibility among the adjoining interphases. The present context exemplifies the development of such dual electrodes with specially engineered morphology to restrict the over-ripening of metallic phase during high temperature treatment and operation. As specific case study, we have tried to describe the significance and trail of core-shell microstructure in improving the long term endurability of fuel cells. In addition, details on processing conditions are discussed which are unique in rendering the core-shell morphology for selective electrode composition applicable for Solid oxide fuel cells.

Water hyacinth (WH), an invasive plant in freshwater bodies in tropical and subtropical regions, poses a severe threat to the aquatic environment, human health, and the livelihoods of people in the surrounding areas. This study presents a sustainable, easy-to-scale approach to valorize WH by converting its stem into high-performance activated carbon (ACs) for application in lithium-ion batteries. The process involves cleaning, chopping, drying, and carbonizing the stem, followed by chemical activation using KOH. The physicochemical properties revealed that ACs have a high surface area of 1600–2450 m2 g–1 with mesoporous structure, and have ordered graphitic domains as confirmed by XRD and Raman. The microstructure revealed a flake-like configuration of grains, as confirmed by FESEM. The activated carbons obtained using different mass ratios of KOH delivered specific capacities of 209–326 mAh g–1 at 0.2 mA cm–2 against lithium when tested in 2032 lithium-ion cells. The fabricated cells were cycled for more than 250 cycles with variable current densities ranging from 0.2 to 1.4 mA cm–2, exhibiting excellent rate capability, coulombic efficiency (>95%), and capacity retention (>70%). This study thus highlights a scalable, eco-friendly method to transform water hyacinth biomass into valuable carbon materials for energy storage, aligning with the global “Waste to Wealth for Energy” initiative.

The present research reports the synthesis of poly­[ethyleneoxide]-basedcomposite films (500 μm) containing metal nanoparticles (NPs)[Ag0 (dp ∼ 6 nm), Cu0 (dp ∼ 25 nm), and Fe0 (dp ∼ 35 nm)] as the mobilephase. The novelty of the study is in the corroboration of a plausiblemechanism for the generation of metal NPs through green synthesisusing herbal extracts of Camellia sinensis (Tea) and Azadirachta indica (Neem).Density functional theory (DFT) is used to optimize the phytoreductantspresent in both biosources, wherein the reducing and/or stabilizingfunctional entities are primarily hydroxyl groups (−OH). Thetransition energy (band gap, ΔE|LUMO–HOMO|) is found to be minimum for Epicatechin gallate (1.05 eV, tea) andSitosterol (0.58 eV, neem), which could act as potent phytoreductantsfor initiating a redox reaction, followed by subsequent capping throughsecondary bond formation. Upon increasing the loading of metal NPsfrom 1 to 7 wt %, the ionic conductivity of a PEO composite increases(0.1 S·cm–1) for PAgN (N: neem).With a subsequent increase in loading (10 wt %), the crystalline regionwithin PEO is enhanced (≥83% using DSC), which restricts theion migration and lowers the charge storage capacity, as studied usingdielectric constants and complex relaxation processes (EIS and DRT).Among all of the compositions, PCuN is observed to exhibitnegligible performance deterioration (Δtan δ for18,500 h → 0). However, PAg system(s) are good ion conductorswith significant dielectric nature, but they suffer from particleripening. Hence, metal NPs, which functionalize PEO films, could beeffectively synthesized using a green synthesis route and appliedas a solid electrolyte for device application.