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Junctions based on electronic ballistic waveguides, such as semiconductor nanowires or nanoribbons with transverse structural variations in the order of a large fraction of their Fermi wavelength, are suggested as highly efficient thermoelectric (TE) devices. Full harnessing of their potential requires a capability to either deterministically induce structural variations that tailor their transmission properties at the Fermi level or alternatively to form waveguides that are disordered (chaotic) but can be structurally modified continuously until favorable TE properties are achieved. Well-established methods to realize either of these routes do not exist. Here, disordered bismuth (Bi) waveguides are reported, which are both formed and structurally tuned by electromigration until their efficiency as TE devices is maximized. In accordance with theory, the conductance of the most efficient TE waveguides is in the sub quantum of conductance regime. The stability of these structures is found to be substantially higher than other actively studied devices such as single molecule junctions., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

The proton exchange membrane water electrolyzer (PEMWE) is one of the most promising electrochemical energy conversion devices for hydrogen production, while still limited by performance bottlenecks at high current densities, due to the lack of mass transfer insights. To investigate the mechanisms of oxygen transport inside the PEMWE at high current density and its relation to electrolytic performance. Operational in situ x-ray imaging is utilized to simultaneously characterize the bubble behavior and voltage response in a novel designed visual mini-cell, and it is identified that oxygen evolution and transport in the PEMWE follow the process of bubble nucleation, growth, and detachment. Based on the results of mini-cells with three porous transport layers (PTLs) up to 9 A cm -2 operation, it revealed that critical current densities exist for both carbon-based and titanium-based PTLs. Once exceeding the critical current density, the cell voltage can no longer be stabilized and the cell exhibits a significant oxygen overpotential. To illustrate this, the concept of interfacial separation zone (ISZ) is first proposed, which is an effective pathway for bubble growth and separation and the pattern of the ISZ exhibits specific regimes with the critical current density. Ultimately, a new approach for better understanding the mechanisms of oxygen transport is revealed., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

The fundamental question of "what is the transport path of electrons through proteins?" initially introduced while studying long-range electron transfer between localized redox centers in proteins in vivo is also highly relevant to the transport properties of solid-state, dry metal-protein-metal junctions. Here, we report conductance measurements of such junctions, Au-( Azurin monolayer ensemble)-Bismuth (Bi) ones, with well-defined nanopore geometry and ~10 3 proteins/pore. Our results can be understood as follows. (1) Transport is via two interacting conducting channels, characterized by different spatial and time scales. The slow and spatially localized channel is associated with the Cu center of Azurin and the fast delocalized one with the protein's polypeptide matrix. Transport via the slow channel is by a sequential (noncoherent) process and in the second one by direct, off-resonant tunneling. (2) The two channels are capacitively coupled. Thus, with a change in charge occupation of the weakly coupled (metal center) channel, the broad energy level manifold, responsible for off-resonance tunneling, shifts, relative to the electrodes' Fermi levels. In this process, the off-resonance (fast) channel dominates transport, and the slow (redox) channel, while contributing only negligibly directly, significantly affects transport by intramolecular gating., Competing Interests: Competing interests statement:The authors declare no competing interest.

We report of a high yield method to form nanopore molecular ensembles junctions containing ~40,000 molecules, in which the semimetal bismuth (Bi) is a top contact. Conductance histograms of these junctions are double-peaked (bi-modal), a behavior that is typical for single molecule junctions but not expected for junctions with thousands of molecules. This unique observation is shown to result from a new form of quantum interference that is inter-molecular in nature, which occurs in these junctions since the very long coherence length of the electrons in Bi enables them to probe large ensembles of molecules while tunneling through the junctions. Under such conditions, each molecule within the ensembles becomes an interference path that modifies via its tunneling phase the electronic structure of the entire junction. This new form of quantum interference holds a great promise for robust novel conductance effects in practical molecular junctions., (© 2022. The Author(s).)