Electrochem

Layered perovskite oxides exhibit significant potential as an electrolyte for moderate-temperature solid-oxide fuel cells (SOFCs) owing to their structural flexibility and ionic transport properties. The study aims to examine the impact of rare-earth element incorporation on the structural, microstructural, and electrical characteristics of the material La₂Ti₂O₇. The layered perovskite was doped with Y³⁺ and Gd³⁺ ions using a conventional solid-state method, followed by thermal sintering at elevated temperatures. Physicochemical characterizations were carried out to examine the structural and morphological properties. Impedance measurements carried out over the temperature range 300–750 °C confirmed improved electrical conductivity in doped samples, and the contributions came from both grain and grain boundary conduction paths. The oxygen vacancy formation and structural changes due to Y and Gd doping improved ionic transport properties. These studies confirmed that rare-earth-doped La₂Ti₂O₇ perovskites are potential materials for improved electrolytes in intermediate-temperature SOFCs.

Wire-arc additive manufacturing (WAAM) offers several advantages in the production of nickel aluminium bronze (NAB) parts for maritime, aviation and petrochemicals industries. Anisotropic material properties, however, have been observed in WAAM and, to date, the variability in corrosion behaviour in NAB processed by WAAM has not been explored. This study addresses the gap by investigating the microstructure and corrosion behaviour of NAB processed by WAAM in the three orthogonal planes (XY, YZ and XZ) compared to a continuously cast sample using microspectroscopy and electrochemical techniques. YZ- and XZ-orientated WAAM samples exhibited layered microstructures with coarser and finer regions. Microstructures appear similar across orientations with elongated α grains, higher proportions of the intergranular region in heat-affected zones and considerably finer κ precipitates compared to the cast NAB. Corrosion resistance across WAAM orientations were comparable to those of casted samples. Increased variability in WAAM corrosion results suggests possible additional locational dependencies beyond orientation alone.

Proton exchange or electrolyte membranes (PEMs) are vital parts of low-temperature fuel cells because they govern proton transport, fuel crossover, water management, and the mechanical and chemical durability of the membrane electrode assembly. Although perfluorosulfonic acid membranes, such as Nafion, remain widely employed, their dependence on fluorinated chemistry, hydration-sensitive conductivity, cost, and methanol crossover has stimulated interest in alternative membrane materials derived from renewable resources. Chitosan (CS), a naturally derived polysaccharide containing abundant amino and hydroxyl functional groups, has emerged as a promising platform material for the development of proton-conducting membranes for polymer electrolyte membrane fuel cells (PEMFCs) and direct-methanol fuel cells (DMFCs). This review critically examines recent advances in chitosan-based membranes, with emphasis on cross-linking, inorganic and carbon-based composite formation, incorporation of bio-derived fillers, polymer blending, and ionic liquid modification. The influence of these strategies on proton conductivity, methanol permeability, water absorption, dimensional stability, mechanical characteristics, thermal and chemical stability, and fuel cell performance is discussed in relation to membrane composition and structure. The reviewed studies demonstrate that targeted modification of chitosan can substantially improve individual membrane properties; however, achieving a simultaneous balance between proton transport, fuel-barrier characteristics, mechanical integrity, hydration, and long-term durability remains challenging. Variations in chitosan characteristics, membrane fabrication, testing conditions, and performance evaluation also hinder direct comparison among reported systems. Future research should therefore emphasize standardized characterization, reproducible membrane fabrication, membrane electrode assembly optimization, long-term single-cell testing, and life-cycle assessment. These developments are essential for translating chitosan-based PEMs from being laboratory-scale materials towards durable and practical fuel cell applications.