Claudio Fontanesi

Enantiorecognition is a fundamental process in bioscience, ruling most life-related processes. This work focuses on the physics underlying chiral recognition, suggesting that the electron-spin/molecular-handedness interaction plays an important role here. Results obtained exploiting three complementary experimental techniques are compared, where metal surfaces are functionalized using a chiral porphyrin (cPorf): (1) cyclic voltammetry is used to probe the handedness of the electrode surface exploiting a chiral redox couple; (2) spin-dependent electrochemistry measurements were performed using a ferromagnetic electrode as spin injector; (3) magnetoconductive atomic force microscopy measurements proved that the charge transport through cPorf bundles adsorbed on a nickel surface is spin-polarized (spin polarization percentage, SP%, ranging between 20% and 50%). Mueller matrix polarimetry (MMP) spectra confirmed that the electronic circular dichroism of cPorf in solid-state thin films is not merely apparent but is true. The overall experimental results suggest that spin plays a fundamental role in the enantiorecognition process, as a possible manifestation of the Naaman−Waldeck chiral-induced spin selectivity effect.

Enantiorecognition is conventionally rationalized through stereochemical models, such as lock-and-key, induced-fit, and three-point interaction schemes, in which a chiral selector discriminates between enantiomers through geometry and noncovalent interactions. Nevertheless, such models are blind to electron spin. Chiral-induced spin selectivity (CISS) brings electron spin explicitly into this picture. Here, we argue that spin-selective charge transfer can provide an additional, predominantly kinetic contribution to enantiorecognition, most clearly expressed out of equilibrium, where it affects adsorption, reaction, or charge-transfer rates. We organize this view as a generator-and-reader scheme: a chiral element under a nonequilibrium drive generates a handedness-locked spin polarization, which is then read either by a ferromagnet, through exchange, or by a second chiral element, through spin matching, with no external magnet required. Recent experiments on magnetic adsorption, electrochemical junctions, organic photoelectrochemical transistors, and magnetization-controlled growth of helical aggregates from achiral units converge on this generator-and-reader structure. Across these platforms (spanning molecular, axial, and emergent mesoscopic chirality), a common signature recurs: a handedness-dependent, spin-selective current at a chiral charge-transfer interface. Rather than replacing stereochemical models, this framework adds a spin-resolved electronic coordinate to them: one that becomes experimentally visible when chiral recognition is coupled to nonequilibrium charge transfer.

In this study, ligand-functionalized carbon black and graphene nanoplatelet supports were employed to obtain atomically dispersed Pd-based catalysts through surface coordination of Pd(II) species. A tris(2-aminoethyl)amine (TREN)-based ligand was used as the coordinating moiety. Palladium was sourced from a [Pd(NH3)2(NO2)2] solution, one of the most widely employed Pd salts in the electroplating industry, at concentrations representative of industrial rinsing waters (0.1 g/L) in the presence of a realistic supporting electrolyte (0.1 M Na2SO4). The proposed strategy enables the recovery of Pd(II) from dilute aqueous streams while directly generating low-Pd-content catalysts, which we tested for the oxygen reduction reaction (ORR). Pristine and functionalized carbon substrates, before and after Pd uptake, were characterized by complementary spectroscopic and electrochemical techniques. TEM and XPS analyses revealed that bare carbon black and graphene nanoplatelets predominantly promote the formation of Pd(0) nanoparticles. In contrast, ligand-functionalized surfaces favor the stabilization of supported Pd(II) coordination sites. The Pd(II)-modified materials exhibited enhanced catalytic activity and markedly improved stability compared to catalysts obtained from nonfunctionalized carbon supports. This behavior is attributed to the transition from easily leachable Pd(0) nanoparticles to molecularly defined Pd(II) surface complexes. Rotating ring(-disk) electrode (RDE/RRDE) measurements indicated a predominant four-electron ORR pathway, enabling the selective reduction of oxygen to water with limited hydrogen peroxide formation. By combining dilute waste-inspired Pd sources with a simple and effective carbon functionalization strategy, this approach contributes to the development of circularity of Pd in the electroplating industry and to the achievement of low-cost catalytic materials for alkaline fuel cell technologies.

The chiral-induced spin selectivity (CISS) effect enables the spin-selective transport of electrons through chiral systems, linking handedness with spin polarization. This review provides a comprehensive examination of the emerging field of chiral electrocatalysis, detailing also the extensive experimental and theoretical endeavor conducted to gain a deeper understanding of the fundamental physical principles and mechanistic characteristics of this phenomenon. In particular, the CISS effect has garnered significant attention within the scientific community due to its potential for broad applicability across several fields, ranging from spintronics to biology. Among them, the prospective harnessing of the CISS effect into electrocatalytic processes offers an innovative strategy to improve the performance of energy conversion and storage technologies. This review deeply examines the practical applications of the CISS effect across different electrocatalytic reactions, with particular emphasis on its influence on the oxygen reduction reaction (ORR) and its critical role in energy conversion systems where the ORR reaction is a key process, such as in metal–air batteries, whose safety and performance can be enhanced through spin-selective electron transport.

The chiral-induced spin selectivity (CISS) effect enables spin-selective transport of electrons through chiral systems, linking handedness with spin polarization. This review provides a comprehensive examination of the emerging field of chiral electrocatalysis, detailing also the extensive experimental and theoretical endeavor conducted to gain a deeper understanding of the fundamental physical principles and mechanistic characteristics of this phenomenon. In particular, the CISS effect has garnered significant attention within the scientific community due to its potential for broad applicability across several fields, ranging from spintronics to biology. Among them, the prospective harnessing of CISS effect into electrocatalytic processes offers an innovative strategy to improve the performance of energy conversion and storage technologies. This review deeply examines the practical applications of the CISS effect across different electrocatalytic reactions, with particular emphasis on its influence on the oxygen reduction reaction (ORR) and its critical role in energy conversion systems where ORR reaction is a key process - such as in metal-air batteries, whose safety and performance can be enhanced through spin-selective electron transport.

This study concerns the simulation of copper electrodeposition and related phenomenological and technological aspects as influenced by electrode geometry and electrolyte flow velocity. A multiphysics simulation approach was employed, integrating mathematical models accounting for electrochemical deposition and hydrodynamic behavior. Ionic transport is described by the Nernst-Planck equations, electrode kinetics by Butler–Volmer expressions, and fluid flow by the Navier–Stokes equations. Simplified 2D and 3D models were developed to investigate industrial frame plating electrodeposition processes. The results indicate that the fluid direction of the solution in relation to the position of the substrate within the electrodeposition cell enables the distribution of the thickness of the coating to be optimized. Numerical simulation can be used to guide the choice of the orientation of cathodes to be electroplated inside the electroplating tank, to take into consideration agitation direction, and to achieve the best deposit uniformity.

This study investigates the influence of sevoflurane and desflurane on the electrochemical behavior of the Fe(III)-acetylacetonate (Fe(acac)₃) complex. Using cyclic voltammetry (CV), we demonstrate that while Fe(acac)₃ exhibits reversible redox behavior in an oxygen-free environment, the presence of dissolved oxygen renders the system irreversible, leading to the formation of a thick, reddish film on the electrode surface upon potential cycling. Notably, the addition of sevoflurane and desflurane restores the electrochemical reversibility and dramatically inhibits this film formation. Raman spectroscopy of the resulting films confirmed structural changes which are consistent with this inhibiting action. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis reveals that the iron in the film remains predominantly in the Fe³⁺ oxidation state even after prolonged electrochemical reduction cycles. These findings suggest that the anesthetics act by inhibiting the interaction between the Fe(acac)₃ complex and oxygen, likely through a spin–decoherence mechanism. This work highlights the critical role of anesthetics in modifying the electrochemical behavior of metal-oxygen complexes, with potential implications for sensing, electrocatalysis, and bio-oriented systems.

The catalytic activity for the hydrogen evolution reaction of three structurally related ruthenium catalysts is compared: a di-nuclear [Ru 2 (OTf)(m-H)(Me 2 dad)(dbcot) 2 ] (C1) and two mononuclear analogues (C2, C3). The reaction mechanism is analyzed at a molecular level by using ab-initio DFT calculation to determine singular-points on the potential energy surface (PES). Then, time dependent behavior is investigated by calculationing molecular dynamic (MD) trajectories, within the Dynamic Reaction Coordinate (DRC) paradigm. Displacement of molecular hydrogen results the ratedetermining step. C2 shows a promising low activation barrier: 8.6 kcal/mol, although H 2 release is kinetically slower. C3 yields molecular hydrogen but fails its release, even when provided with kinetic energy larger than the activation barrier (24.4 kcal/mol), revealing unforeseen mechanistic traps, beyond purely energetic considerations. This work underscores how ligand coordination flexibility critically affects the efficiency of hydrogen catalysis, paving the way for the rational design of novel catalysts.

This work presents an unconventional device designed via integration of an electrochemical cell and a solid-state circuitry resembling a triode-like configuration, referred to as an electrochemical-transistor-like (ETL) device.