The presence of defects and chemical dopants in metal-free carbon materials plays an important role in the electrocatalysis of the oxygen reduction reaction (ORR). The precise control and design of defects and dopants in carbon electrodes will allow the fundamental understanding of activity-structure correlations for tailoring catalytic performance of carbon-based, most particularly graphene-based, electrode materials. Herein, we adopted monolayer graphene – a model carbon-based electrode – for systematical introduction of nitrogen and oxygen dopants, together with vacancy defects, and studied their roles in catalyzing ORR. Compared to pristine graphene, nitrogen doping exhibited a limited effect on ORR activity. In contrast, nitrogen doping in graphene predoped with vacancy defects or oxygen enhanced the activities at 0.4 V vs the reversible hydrogen electrode (RHE) by 1.2 and 2.0 times, respectively. The optimal activity was achieved for nitrogen doping in graphene functionalized with oxygenated defects, 12.8 times more than nitrogen-doped and 7.7 times more than pristine graphene. More importantly, oxygenated defects are highly related to the 4e – pathway instead of nitrogen dopants. This work indicates a non-negligible contribution of oxygen and especially oxygenated vacancy defects for the catalytic activity of nitrogen-doped graphene.

Lithium ion selective crown ethers have been the subject of much research for a multitude of applications. Current research is aimed at structurally rigidifying crown ethers, as restructuring of the crown ether ring upon ion binding is energetically unfavorable. In this work, the lithium ion binding ability of the relatively rigid 8‐crown‐4 was investigated both computationally by density functional theory calculations and experimentally by 1H and 7Li NMR spectroscopy. Although both computational and experimental results showed 8‐crown‐4 to bind lithium ion, this binding was found to be weak compared to larger crown ethers. The computational analysis revealed that the complexation is driven by enthalpy rather than entropy, illustrating that rigidity is only of nominal importance. To elucidate the origin of the favorable interaction of lithium ion with crown ethers, activation strain analyses and energy decomposition analyses were performed pointing to the favorable interaction being mainly electrostatic in nature. 8‐crown‐4 presents the smallest crown ether reported to date capable of binding lithium ion, possessing two distinct conformations from which it is able to do so.

The Angstrom-scale space between graphene and its substrate provides an attractive playground for scientific exploration and can lead to breakthrough applications. Here, we report the energetics and kinetics of hydrogen electrosorption on a graphene-covered Pt(111) electrode using electrochemical experiments, in situ spectroscopy, and density functional theory calculations. The graphene overlayer influences the hydrogen adsorption on Pt(111) by shielding the ions from the interface and weakening the Pt–H bond energy. Analysis of the proton permeation resistance with controlled graphene defect density proves that the domain boundary defects and point defects are the pathways for proton permeation in the graphene layer, in agreement with density functional theory (DFT) calculations of the lowest energy proton permeation pathways. Although graphene blocks the interaction of anions with the Pt(111) surfaces, anions do adsorb near the defects: the rate constant for hydrogen permeation is sensitively dependent on anion identity and concentration.

Coiled-coil peptides are high-affinity, selective, self-assembling binding motifs, making them attractive components for the preparation of functional biomaterials. Photocontrol of coiled-coil self-assembly allows for the precise localization of their activity. To rationally explore photoactivity in a model coiled coil, three azobenzene-containing amino acids were prepared and substituted into the hydrophobic core of the E3/K3 coiled-coil heterodimer. Two of the non-natural amino acids, APhe1 and APhe2, are based on phenylalanine and differ in the presence of a carboxylic acid group. These have previously been demonstrated to modulate protein activity. When incorporated into peptide K3, coiled-coil binding strength was affected upon isomerization, with the two variants differing in their most folded state. The third azobenzene-containing amino acid, APgly, is based on phenylglycine and was prepared to investigate the effect of amino acid size on photoisomerization. When APgly is incorporated into the coiled coil, a 4.7-fold decrease in folding constant is observed upon trans-to-cis isomerizationthe largest difference for all three amino acids. Omitting the methylene group between azobenzene and α-carbon was theorized to both position the diazene of APgly closer to the hydrophobic amino acids and reduce the possible rotations of the amino acid, with molecular dynamics simulations supporting these hypotheses. These results demonstrate the ability of photoswitchable amino acids to control coiled-coil assembly through disruption of the hydrophobic interface, a strategy that should be widely applicable.

Molecularly thin, nanoporous thin films are of paramount importance in material sciences. Their use in a wide range of applications requires control over their chemical functionalities, which is difficult to achieve using current production methods. Here, the small polycyclic aromatic hydrocarbon decacyclene is used to form molecular thin films, without requiring covalent crosslinking of any kind. The 2.5 nm thin films are mechanically stable, able to be free-standing over micrometer distances, held together solely by supramolecular interactions. Using a combination of computational chemistry and microscopic imaging techniques, thin films are studied on both a molecular and microscopic scale. Their mechanical strength is quantified using AFM nanoindentation, showing their capability of withstanding a point load of 26 ± 9 nN, when freely spanning over a 1 μm aperture, with a corresponding Young’s modulus of 6 ± 4 GPa. Our thin films constitute free-standing, non-covalent thin films based on a small PAH.

As one of the most promising platforms for wireless communication, radiofrequency (RF) electronics have been widely advocated for the development of sensing systems. In particular, monolayer and few-layer two-dimensional (2D) materials exhibiting extraordinary electrical properties not only can be integrated to improve the performances of RF circuits, but also to display exceptional sensing capabilities. This review provides an in-depth perspective of current trends and challenges in the application of 2D materials for RF biochemical sensing, including: i) theoretical bases to achieve different sensing schemes; ii) unique properties of 2D materials for reasoning their applications in RF sensing; iii) developments in 2D RF sensors to facilitate the practice of biochemical sensors with ever-demanding sensitivities, as well as their potential uses in meeting the requirements and challenges of biochemical sensors in the Internet-of-Things (IoT) era.

phenanthrene (CPP) is a valuable building block in the production of photoactive polymers, which find use in a wide range of organic electronic applications. Of particular importance is their use in the development of bluecolored, organic light-emitting diodes (OLEDs), which remains a challenge in the field. Unfortunately, commercial sources and synthetic procedures known in the literature are unable to provide enough CPP for large scale implementation. Herein, we report on the development of a novel, gram-scale synthesis of CPP in three steps, starting from pyrene. The key steps in our methodology are the ring contraction of pyrene-4,5-dione to oxoCPP in a single step, as well as the direct reduction of oxoCPP to CPP. Apart from the small number of synthetic steps, our methodology benefits from the use of relatively nonhazardous reagents, together with optimized purification procedures, making CPP accessible in useful quantities.

Specifically for photo detection purposes, the generation of finite bandgaps minimizes the dark current and maximizes the on/off current ratios. [5] From a mechanical perspective, a high aspect ratio graphene strip (in practice with microscale widths) can be driven to resonate; graphene based resonators, combining the outstanding Young's modulus, [6] ultra-low mass and electronic conductivity, are of great interests, e.g., in mass/force sensing [7] and radio frequency readout/filtration. [8] Graphene nanoribbons, on the other hand, have been integrated into composite systems: It has been demonstrated that metal oxide nanoparticles efficiently interact with the surface of graphene nanoribbons and achieve nanoscale mixings; such composite materials have found applications as anodes for lithium-ion batteries. [9,10] High-throughput graphene nanoribbon-based conductive coatings have been also realized, with applications, e.g., as radio-frequency-transparent heating elements. [11,12] From a chemical perspective, the interest in graphene ribbons stems from the outstanding chemical reactivity of edge atoms: Atoms on the edge sites are distinct from the inner atoms as the result of unsaturated p z orbitals and interrupted π conjugation. [13] In fact, the local elec-