RESSALVA Atendendo solicitação do(a) autor(a), o texto completo deste documento será disponibilizado somente a partir de 26/08/2027. GABRIELA DIAS DA SILVA Electronic and Electrochemistry at Nanoscale: fundamentals and applications Araraquara-SP 2025 GABRIELA DIAS DA SILVA Electronic and Electrochemistry at Nanoscale: fundamentals and applications Final Report of Postdoctoral research (September, 2021 to January, 2025), process 2021/07936-8, presented as UNESP require- ment. UNIVERSIDADE ESTADUAL PAULISTA “JÚLIO DE MESQUITA FILHO” Araraquara-SP 2025 Contents 1 ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Quantum Capacitance and Electron Transfer at the Nanoscale . . . 4 2.2 Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Computational Details . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3 1 Abstract Electron transfer (ET) is a cornerstone of energy conversion processes, playing a pivotal role in optimizing electrochemical devices and advancing biosensing technologies. As these technologies evolve toward greater miniaturization and enhanced sensitivity, the study of nanoscale electrochemistry—particularly the influence of quantum effects—has become an increasingly pressing challenge. Self-assembled monolayers (SAMs), composed of thiol- functionalized molecules chemically anchored to metal surfaces, provide a highly tunable platform for probing ET mechanisms at the molecular level. The intricate interplay between molecular dynamics, electronic properties, and structural organization within SAMs governs the efficiency and directionality of charge transfer. Additionally, single-layer graphene (SLG) has emerged as a well-established model for exploring nanoelectronic behavior, offering complementary insights into ET processes. Given their distinct yet interrelated characteristics, both SAMs and SLG were investigated in this study. Despite significant advances in understanding quantum effects in ET, the precise contributions of electrical and chemical properties at the nanoscale remain elusive, warranting further theoretical and computational exploration. To address this gap, we employed a hybrid molecular modeling strategy that integrates quantum and classical approaches to offer a more holistic perspective on ET dynamics. Specifically, a Quantum Mechanics/Molecular Mechanics (QM/MM) framework was combined with non-equilibrium Green’s functions (NEGF) calculations, implemented within the Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) code, to unravel the underlying electronic mechanisms of charge transfer. Complementary classical Molecular Dynamics (MD) simulations, performed using the GROningen MAchine for Chemical Simulations (GROMACS) code, provided insights into the structural evolution of SAMs in explicit solvent environments (water and acetonitrile), capturing the dynamic fluctuations that influence ET pathways. By integrating these methodologies under non-equilibrium conditions, this study presents a comprehensive framework for investigating nanoscale ET with direct implications for the rational design of high-performance biochemical devices. Through a detailed examination of SAM architectures, we systematically evaluated charge transfer processes between gold electrodes and redox-active ferrocene (Fc) moieties using advanced QM/MM+NEGF molecular modeling techniques. Furthermore, we analyzed the electronic structure of SLG and correlated our computational findings with experimental data, offering a deeper understanding of its role in nanoelectronic applications. These results contribute to a more nuanced comprehension of ET at the molecular scale, providing valuable insights into the design principles of next-generation electrochemical and biosensing platforms. 10 Conclusion This study deepens our understanding of electron transfer mechanisms at the nanoscale by combining electronic structure analysis, molecular dynamics simulations, and hybrid QM/MM methodologies. By examining self-assembled monolayers (SAMs) and single-layer graphene (SLG), we have revealed the complex electrochemical processes driving charge transfer in molecular systems. Our findings underscore the significant role of solvation effects, structural conformation, and redox activity, offering critical insights for the design of advanced electrochemical devices with enhanced efficiency and precision. We also explored SLG’s electronic properties using density functional theory (DFT) and highlighted how doping and oxidation impact its quantum capacitance and density of states (DOS). These factors were confirmed through electrochemical impedance spec- troscopy (EIS), showing distinct charge transfer regimes. Additionally, MD and QM/MM studies on SAMs illustrated how solvent structuring influences electron transfer, particu- larly in acetonitrile and water-NaCl mixtures. This research lays the groundwork for future studies into graphene-based materials and emerging two-dimensional materials, promising breakthroughs in energy storage, catalysis, and molecular diagnostics. By correlating computational insights with experimental validation, we are poised to reshape the future of electrochemical nanotechnology. 11 Teaching I was responsible for teaching the undergraduate course Physics I (EBB002 – Theoretical component) at the UNESP Araraquara campus. 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RESSALVA.pdf silva_gd_relatorioposdoc_araiq_par.pdf Title page Contents Abstract Introduction Quantum Capacitance and Electron Transfer at the Nanoscale Goals Computational Details Bibliography