This study investigates the synthesis and electrochemical performance of Zn-MOF and Zn-Fe MOF composites as electrode materials for high-performance supercapacitors. Metal-organic frameworks (MOFs) have attracted considerable attention for energy storage applications owing to their tunable porosity and large specific surface area; however, their inherently low electrical conductivity and susceptibility to active-site blockage remain key limitations. Electrochemical evaluation revealed that the Zn-Fe MOF electrode delivered a specific capacitance of 121.02 F g-& sup1; and a specific capacity of 162 mAh g-& sup1;, compared with 108.00 F g-& sup1; and 32 mAh g-& sup1; for the pristine Zn-MOF. The composite exhibits distinct redox peaks in cyclic voltammetry, confirming faradaic charge storage behaviour, further corroborated by Electrochemical Impedance Spectroscopy (EIS). The Zn-Fe MOF electrode achieves an energy density of 4.3 Wh kg-& sup1; and a power density of 910 W kg-& sup1;, while retaining 98.58% of its initial capacitance after 3000 charge-discharge cycles, demonstrating exceptional long-term stability. Dunn's deconvolution analysis revealed that diffusion-controlled (faradaic) processes dominate at low scan rates (53% at 5 mV s-& sup1;), whereas capacitive contributions prevail at high scan rates (94% at 200 mV s-& sup1;). These findings establish Zn-Fe MOF composites as promising electrode materials that effectively combine structural stability with enhanced faradaic energy storage. Cette & eacute;tude examine la synth & egrave;se et les performances & eacute;lectrochimiques des composites Zn-MOF et Zn-Fe MOF comme mat & eacute;riaux d'& eacute;lectrode pour supercondensateurs & agrave; haute performance. Les structures organom & eacute;talliques (MOF) ont suscit & eacute; un int & eacute;r & ecirc;t consid & eacute;rable pour le stockage d'& eacute;nergie, en raison de leur porosit & eacute; ajustable et de leur grande surface sp & eacute;cifique; cependant, leur faible conductivit & eacute; & eacute;lectrique intrins & egrave;que et leur sensibilit & eacute; au blocage des sites actifs demeurent des limitations cl & eacute;s. L'& eacute;valuation & eacute;lectrochimique a r & eacute;v & eacute;l & eacute; que l'& eacute;lectrode Zn-Fe MOF pr & eacute;sentait une capacit & eacute; massique de 121.02 F g-1 et une capacit & eacute; de charge de 162 mAh g-1, contre 108.00 F g-1 et 32 mAh g-1 pour le Zn-MOH pur. Le composite pr & eacute;sente des pics r & eacute;dox distincts en voltamp & eacute;rom & eacute;trie cyclique, ce qui confirme un comportement de stockage de charge faradique, corrobor & eacute; par spectroscopie d'imp & eacute;dance & eacute;lectrochimique (EIS). L'& eacute;lectrode Zn-Fe MOF atteint une densit & eacute; & eacute;nerg & eacute;tique de 4.3 Wh kg-1 et une densit & eacute; de puissance de 910 W kg-1, tout en retenant 98.58% de sa capacit & eacute; initiale apr & egrave;s 3000 cycles de charge-d & eacute;charge, d & eacute;montrant une stabilit & eacute; & agrave; long terme exceptionnelle. L'analyse de d & eacute;convolution de Dunn a r & eacute;v & eacute;l & eacute; que les proc & eacute;d & eacute;s contr & ocirc;l & eacute;s par diffusion (faradiques) dominent aux faibles vitesses de balayage (53% & agrave; 5 mV s-1), tandis que les contributions capacitives pr & eacute;valent aux vitesses de balayage & eacute;lev & eacute;s (94% & agrave; 200 mV s-1). Ces r & eacute;sultats & eacute;tablissent les composites Zn-Fe MOF comme des mat & eacute;riaux d'& eacute;lectrode prometteurs, combinant efficacement stabilit & eacute; structurelle et stockage d'& eacute;nergie faradique am & eacute;lior & eacute;.
This study examines the combined effects of operating parameters on silver purity and crystal morphology during electrorefining. Applied voltage (1.5-2.7 V), electrolyte silver concentration (50-100 g/L), copper ion concentration (10-50 g/L), and electrolyte pH (1-3) were systematically investigated. The results showed that compact deposits with high solidity values (approximate to 0.87-0.88) were obtained at low voltage (1.5 V), low copper concentration (10 g/L), and moderate silver concentration (50 g/L). Increasing voltage or copper concentration promoted branching and dendritic growth, whereas higher pH values led to more uniform deposit structures. In contrast, silver purity was primarily governed by electrolyte composition. Analysis of Variance (ANOVA) revealed that silver concentration had a statistically significant positive effect on purity, while copper concentration had a statistically significant negative effect; pH exhibited no statistically significant effect on purity, and voltage showed only a minor influence. The highest purity of 99.9994% (approximate to 0.6 ppm Cu) was achieved at 100 g/L Ag, 10 g/L Cu, and 1.5 V. These findings demonstrate that crystal morphology and purity are controlled by distinct electrochemical mechanisms, and that integrating CCD with quantitative image analysis provides an effective approach for optimising both deposit structure and ultra-high purity in silver electrorefining. Cette & eacute;tude examine les effets des param & egrave;tres op & eacute;ratoires sur la puret & eacute; de l'argent et la morphologie cristalline lors de l'& eacute;lectroaffinage, & agrave; l'aide d'un plan composite centr & eacute; (PCC). On a & eacute;tudi & eacute; syst & eacute;matiquement la tension appliqu & eacute;e (1.5 & agrave; 2.7 V), la concentration en argent de l'& eacute;lectrolyte (50 & agrave; 100 g/L), la concentration en ions cuivre (10 & agrave; 50 g/L) et le pH de l'& eacute;lectrolyte (1 & agrave; 3). On a analys & eacute; quantitativement la morphologie cristalline & agrave; l'aide d'ImageJ, la solidit & eacute; & eacute;tant choisie comme param & egrave;tre morphologique repr & eacute;sentatif, tandis que l'on a d & eacute;termin & eacute; la puret & eacute; de l'argent par l'analyse r & eacute;siduelle du cuivre par spectroscopie d'absorption atomique (AAS). Les r & eacute;sultats ont montr & eacute; que des d & eacute;p & ocirc;ts compacts & agrave; solidit & eacute; & eacute;lev & eacute;e (environ 0.87-0.88) & eacute;taient obtenus & agrave; basse tension (1.5 V), & agrave; une faible concentration en cuivre (10 g/L) et & agrave; une concentration mod & eacute;r & eacute;e en argent (50 g/L). L'augmentation de la tension ou de la concentration en cuivre favorisait la croissance ramifi & eacute;e et dendritique, tandis que les valeurs de pH plus & eacute;lev & eacute;es conduisaient & agrave; des structures de d & eacute;p & ocirc;t plus uniformes. En revanche, la puret & eacute; de l'argent & eacute;tait gouvern & eacute;e principalement par la composition de l'& eacute;lectrolyte. On a obtenu la puret & eacute; maximale de 99.9994% (environ 0.6 ppm Cu) & agrave; 100 g/L Ag, 10 g/L Cu et 1.5 V. Ces r & eacute;sultats d & eacute;montrent que la morphologie et la puret & eacute; des cristaux sont contr & ocirc;l & eacute;es par des m & eacute;canismes & eacute;lectrochimiques distincts, et qu'en int & eacute;grant le PCC & agrave; l'analyse quantitative d'images offre une approche efficace pour optimiser & agrave; la fois la structure du d & eacute;p & ocirc;t et la puret & eacute; ultra-haute lors de l'& eacute;lectroaffinage de l'argent.
Direct Metal Laser Sintering (DMLS) enables the fabrication of complex metallic components with excellent dimensional accuracy and tailored microstructures. This study investigates the effect of heat treatment and laser micro-engraving on the microstructure and biocompatibility of DMLS-processed Inconel 718 alloy. The fabricated specimens were subjected to solution treatment followed by double ageing to promote gamma ' and gamma '' precipitates. Optical microscopy and scanning electron microscopy revealed that heat treatment transformed the dendritic as-built microstructure into a homogeneous equiaxed structure. Laser micro-engraving produced well-defined surface textures, with the heat-treated alloy exhibiting higher surface roughness and enhanced surface activity. Biocompatibility was evaluated using an MTT assay with L929 fibroblast cells. After 72 h of exposure, the as-built alloy exhibited a cell viability of 79.9%, whereas the heat-treated alloy achieved 84.1%, corresponding to an improvement of approximately 5.3%. Microscopic observations further confirmed improved cell attachment and spreading on the heat-treated surface. The results indicate that heat treatment combined with laser micro-engraving enhances the biological performance of DMLS-processed Inconel 718 for potential biomedical applications.
