Charge Effects and Electron Phonon Coupling in Potassium-Doped Graphene.

Herewith, we propose a comprehensive study of the vibrational response of chemical doping of free-standing graphene (Gr). Complementary insights on the increased metallicity have been demonstrated by the emerging plasmon excitation in the upper Dirac cone, observed by inelastic electron scattering and core-level photoemission. The electron migration in the π* upper Dirac band unveils an electron-phonon coupling of contaminant-free K-doped Gr, as evidenced by advanced micro-Raman spectroscopy in ultrahigh vacuum ambient.

Toluene-Poisoning-Resistant High-Entropy Non-Noble Metal Anode for Direct One-Step Hydrogenation of Toluene to Methylcyclohexane.

The direct one-step hydrogenation of toluene to methylcyclohexane facilitated by a proton-exchange membrane water electrolyzer driven by renewable energy has garnered considerable attention for stable hydrogen storage and safe hydrogen transportation. However, a persistent challenge lies in the crossover of toluene from the cathode to the anode chamber, which deteriorates the anode and decreases its energy efficiency and lifetime. To address this challenge, the catalyst-poisoning mechanism is systematically investigated using IrO and high-entropic non-noble-metal alloys as anodes in acidic electrolytes saturated with toluene and toluene-oxidized derivatives, such as benzaldehyde, benzyl alcohol, and benzoic acid.

Suppression of Methanol and Formate Crossover through Sulfanilic-Functionalized Holey Graphene as Proton Exchange Membranes.

Proton exchange membranes with high proton conductivity and low crossover of fuel molecules are required to realize advanced fuel-cell technology. The selective transportation of protons, which occurs by blocking the transportation of fuel molecules across a proton exchange membrane, is crucial to suppress crossover while maintaining a high proton conductivity. In this study, a simple yet powerful method is proposed for optimizing the crossover-conductivity relationship by pasting sulfanilic-functionalized holey graphenes onto a Nafion membrane.

1T/1H-SnS Sheets for Electrochemical CO Reduction to Formate.

Understanding the catalytic mechanism of highly active two-dimensional electrocatalysts is crucial to their rational design. Herein, we reveal the element dependence of the reactivity of two-dimensional metal dichalcogenide sheets for electrocatalytic CO reduction. We found that tin(IV) disulfide (SnS) and molybdenum(IV) disulfide (MoS) sheets exhibited Faradaic efficiencies of 63.

Tuning the Electronic Response of Metallic Graphene by Potassium Doping.

Electron doping of graphene has been extensively studied on graphene-supported surfaces, where the metallicity is influenced by the substrate. Herewith we propose potassium adsorption on free-standing nanoporous graphene, thus eluding any effect due to the substrate. We monitor the electron migration in the π* downward-shifted conduction band.

Corrosion-Resistant and High-Entropic Non-Noble-Metal Electrodes for Oxygen Evolution in Acidic Media.

To realize a sustainable hydrogen economy, corrosion-resistant non-noble-metal catalysts are needed to replace noble-metal-based catalysts. The combination of passivation elements and catalytically active elements is crucial for simultaneously achieving high corrosion resistance and high catalytic activity. Herein, the self-selection/reconstruction characteristics of multi-element (nonary) alloys that can automatically redistribute suitable elements and rearrange surface structures under the target reaction conditions during the oxygen evolution reaction are investigated.

Coexistence of Urbach-Tail-Like Localized States and Metallic Conduction Channels in Nitrogen-Doped 3D Curved Graphene.

Nitrogen (N) doping is one of the most effective approaches to tailor the chemical and physical properties of graphene. By the interplay between N dopants and 3D curvature of graphene lattices, N-doped 3D graphene displays superior performance in electrocatalysis and solar-energy harvesting for energy and environmental applications. However, the electrical transport properties and the electronic states, which are the key factors to understand the origins of the N-doping effect in 3D graphene, are still missing.

Homogeneous Spatial Distribution of Deuterium Chemisorbed on Free-Standing Graphene.

Atomic deuterium (D) adsorption on free-standing nanoporous graphene obtained by ultra-high vacuum D2 molecular cracking reveals a homogeneous distribution all over the nanoporous graphene sample, as deduced by ultra-high vacuum Raman spectroscopy combined with core-level photoemission spectroscopy. Raman microscopy unveils the presence of bonding distortion, from the signal associated to the planar sp2 configuration of graphene toward the sp3 tetrahedral structure of graphane. The establishment of D-C sp3 hybrid bonds is also clearly determined by high-resolution X-ray photoelectron spectroscopy and spatially correlated to the Auger spectroscopy signal.

Chemical Dopants on Edge of Holey Graphene Accelerate Electrochemical Hydrogen Evolution Reaction.

Carbon-based metal-free catalysts for the hydrogen evolution reaction (HER) are essential for the development of a sustainable hydrogen society. Identification of the active sites in heterogeneous catalysis is key for the rational design of low-cost and efficient catalysts. Here, by fabricating holey graphene with chemically dopants, the atomic-level mechanism for accelerating HER by chemical dopants is unveiled, through elemental mapping with atomistic characterizations, scanning electrochemical cell microscopy (SECCM), and density functional theory (DFT) calculations.