arXiv subjects

Mohammed F. Kalady

Publications and source records attributed to Mohammed F. Kalady.

3 recordsLinked to original sources

arXiv2026

Interplay of Composition, Crystallinity, and Chemical Structure in CoHCF and NiHCF Thin Films Prepared at Different Temperatures

Understanding how growth conditions govern structural order and ion transport in Prussian blue analogues (PBAs) thin films is essential for optimizing their electrochemical performance. Here, cobalt and nickel hexacyanoferrate (CoHCF and NiHCF) thin films were electrodeposited potentiostatically at temperatures between 20 and 60 degrees C. A combination of cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and Raman spectroscopy was employed to elucidate the interplay between composition, crystallinity, and chemical structure. Under identical conditions, CoHCF exhibits a maximum current density approximately 2.2 times higher than NiHCF, indicating significantly faster electrochemical kinetics. X-ray diffraction reveals temperature-dependent lattice expansion without phase transitions, with a maximum near 40 degrees C, associated with structural relaxation and compositional variations. Raman spectroscopy further reveals temperature-dependent local structural evolution, where cyanide band narrowing at intermediate temperatures indicates improved short-range order, while band broadening at higher temperatures reflects increased defect density. These findings demonstrate that temperature-controlled defect redistribution governs both short- and long-range structural order in PBA thin films, directly influencing ion transport and electrochemical response. This work provides new insights into structure-property relationships in PBAs and establishes deposition temperature as a key parameter for tuning electrochemical functionality in hexacyanoferrate-based electrodes.

cond-mat.mtrl-sci↗

arXiv2026

Electrolyte Dependent Structure Transport Relationships in Electrodeposited Prussian Blue Analogue Thin Films

Understanding how electrolyte composition influences charge storage in Prussian blue analogues (PBAs) requires clarifying the coupled effects of structural disorder and ion transport. Here, we investigate Fe-, Co-, and Ni-based hexacyanoferrate thin films electrodeposited from KCl, NaCl, NH4Cl, and LiCl electrolytes under identical electrochemical conditions. Although all films retain the cubic PBA structure, electrolyte identity produces pronounced differences in lattice parameters, defect concentration, and local coordination environments. Na+ promotes lattice expansion accompanied by increased vacancy formation, microstrain, and structural heterogeneity, whereas K+ and NH4+ yield more structurally coherent frameworks. Raman spectroscopy shows that increasing structural disorder broadens the distribution of local coordination environments and correlates with increasingly dispersed electrochemical behavior. Electrochemical impedance spectroscopy further reveals coupled ion-electron transport, with impedance increasing by more than one order of magnitude from FeHCF to NiHCF. Notably, the CPE exponent decreases systematically with Raman band broadening, establishing a direct correlation between structural disorder and transport dispersion. These results demonstrate that electrolyte identity controls not only lattice dimensions but also the organization and connectivity of defect networks, highlighting structural coherence and accessible transport pathways as key factors governing electrochemical performance in PBA thin films.

cond-mat.mtrl-sci↗

arXiv2026

Electrodeposited Co and Ni Hexacyanoferrates: Insights into Structure and Morphology

Prussian blue (PB) and its analogues (PBAs) are interesting materials for electrochemical applications due to their tunable redox chemistry and open framework structure. In this study, hexacyanoferrates (HCF) containing iron (FeHCF), cobalt (CoHCF) and nickel (NiHCF) were synthesized via potentiostatic electrodeposition. Cyclic voltammetry revealed distinct redox behaviors. Morphological characterization (SEM, EDX) demonstrated uniform, pyramidal film growth for FeHCF and CoHCF. Otherwise, NiHCF presented a cracked film with cubic clusters on top due to residual stress. Despite this, homogeneous element distribution was found for all samples. Structural characterization (TEM and XRD) confirmed a cubic lattice crystal structure for all films, with systematic lattice contraction from Fe to Co to Ni due to decreasing atomic radius. Raman and XPS data revealed a shift toward Fe2+ dominant oxidation states and modifications in CN bonding with the influence of K+ and water occupancy in the PBAs framework. These findings illustrate how metal substitution and deposition parameters can tune the structural and electrochemical properties of PBA films, presenting a strategic route to design tailored electrodes.

cond-mat.mtrl-sci↗