Clara Santato

Cuttlefish ink (Sepia ink) has biological functions such as defense and camouflage. The use of this black‐brown ink in writing and drawing dates to ancient times. In this work, we found that edible cuttlefish ink is a naturally formulated conductive ink where the conductive component includes the biopigment eumelanin. There are no naturally formulated conductive inks reported in the literature. With the long‐term objective to develop a bio‐based printable electronic ink, we carried out an explorative study of edible cuttlefish ink through an integrated approach of chemistry‐structure‐electrical properties. We revealed the elemental and molecular composition of the ink by Instrumental Neutron Activation Analysis and Ultra High‐Pressure Liquid Chromatography coupled with High‐Resolution Mass Spectrometry. We probed the electrical response of spin‐coated ink samples through current–voltage and current–time characteristics and thoroughly characterized their structure and composition by scanning electron microscopy and energy dispersive X‐ray spectroscopy. In ambient conditions, we observed the presence of electronic transport, with a conductivity of about 3.4 ± 1.0 × 10 ⁻⁴ S/cm at 1 V. Current–time characteristics indicate the simultaneous presence of ionic transport. Our work contributes to the development of bio‐based, biocompatible, and biodegradable printable electronics inks and advances the understanding of the biorole of cuttlefish ink.

Transition metal dichalcogenides (TMDs) are emerging layered materials suited for applications in electronics, optoelectronics, and sensing thanks to their semiconductor nature. More recently, electric‐field tuning of surface carrier density through carrier accumulation or depletion in TMDs‐based field‐effect‐transistor devices has been attracting a great deal of interest as a new method to control superconductivity in this class of materials. Such results were achieved by means of ionic liquids (ILs) acting as a gating medium for MoS ₂ crystals. Despite the intensive use of ILs for gating TMDs‐based transistors, the impact of the chemical structure of the ions on the induced charge density, a key parameter for controlling the critical temperature ( T _c ) in superconducting MoS ₂ crystals, is still lacking. Here we demonstrate that ionic liquid gating of MoS ₂ channels using [EMIM][TFSI] or [EMIM][BF ₄ ] can lead to different carrier densities. [TFSI]‐based systems exhibit steeper voltage decay (compared to [BF ₄ ]‐based systems) meaning the potential drops more rapidly across the electric double layer, indicating stronger local electric fields and more efficient charge accumulation in the MoS ₂ channel. Our findings represent the first, yet important, step that paves the way towards controlling charge carrier densities on demand in TMDs by chemical design of the anion and cation pair.

Cyclic voltammetry (CV) is a foundational electroanalytical technique for investigating redox behaviour and evaluating material performance across fields such as molecular electrochemistry, electrocatalysis, sensing, and energy storage. Despite its widespread use, a gap remains between formal electrochemical theory and the practical data analysis required for chemical engineering applications. This review addresses that gap by treating the voltammogram as a multidimensional source of mechanistic and quantitative information rather than as a purely qualitative profile. A theoretical framework is presented for CV, including the governing principles of interfacial electron‐transfer kinetics, mass‐transport regimes, and the distinction between capacitive currents and faradaic processes. To support reliable and reproducible measurements, practical guidance is provided for controlling key experimental variables, including uncompensated resistance, supporting electrolyte effects, scan rate, and potential window selection. Beyond basic peak identification, methods for extracting and interpreting quantitative descriptors are also discussed, including formal and onset potentials, apparent rate constants, electrochemically active surface area, transport regimes, apparent Michaelis–Menten parameters, and capacitance‐ or capacity‐based metrics. Particular attention is given to major sources of uncertainty, including non‐ideal mass transport, film heterogeneity, and fouling, which can distort mechanistic interpretation in complex engineering systems. Recent integration of CV with operando mass spectrometry, spectroscopy, and nanoscale imaging further illustrates how the technique has evolved into a coordinated platform for mechanistic and process‐level analysis in electrochemical engineering. In doing so, the review highlights how CV can support the rational design of robust and scalable electrochemical technologies.

Hydration alters EPR signatures and reduces M _s and M _r in Sepia melanin, while ferromagnetism persists beyond 360 K. INAA/XPS indicates that magnetism arises primarily from intrinsic organic radicals, not detected metals.