An understanding of electrochemical dynamics at solid−liquid interfaces is essential to develop advanced batteries and fuel cells and so on. For example, an atomic-level understanding of electrochemical Pt dissolution and redeposition behavior is crucial for optimizing the material design and operating conditions of polymer electrolyte fuel cells (PEFCs). This understanding enables the prevention of the degradation of Pt nanoparticles used as electrocatalysts. However, the mechanisms of Pt dissolution and redeposition are still not fully understood due to the lack of spatial resolution available with current observation techniques. Here, we have revealed for the first time atomic-level electrochemical Pt dissolution and redeposition behavior using in-house-developed observation techniques. We achieved atomic-level observations of closed-cell type liquid electrochemical transmission electron microscopy (TEM) by combining in-housedeveloped microelectromechanical system (MEMS) chips as an electrochemical cell, an aberration-corrected TEM apparatus, and an energy filter. Furthermore, accurate and stable potential control was achieved using an in-house-developed reversible hydrogen electrode (RHE) with a liquid junction connected to the outside of a TEM specimen holder. Our observation results confirmed that Pt dissolves from surface step edges layer-by-layer, as previously predicted by the density functional theory (DFT). The observation techniques developed are also applicable to other research fields concerning electrochemistry.
Abstract. This paper describes high-resolution waveform matching based on a Phase-Only Correlation (POC) technique and its application for a side-channel attack. Such attacks, such as Simple Power Analysis (SPA) and Differential Power Analysis (DPA), use a statistical analysis of signal waveforms (e.g., power traces) to reduce noise and to retrieve secret information. However, the waveform data often includes displacement errors in the measurements. The use of phase components in the discrete Fourier transforms of the waveforms makes it possible to estimate the displacements between the signal waveforms with higher resolution than the sampling resolution. The accuracy of a side-channel attack can be enhanced using this high-resolution matching method. In this paper, we demonstrate the advantages of the POC-based method in comparison with conventional approaches through experimental DPA and Differential ElectroMagnetic Analysis (DEMA) against a DES software implementation on a Z80 processor.
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