Selective Electrochemical Oxygen Reduction to Hydrogen Peroxide by Confinement of Cobalt Porphyrins in a Metal-Organic Framework.

Sustainable alternatives for the energy intensive synthesis of HO are necessary. Molecular cobalt catalysts show potential but are typically restricted by undesired bimolecular pathways leading to the breakdown of both HO and the catalyst. The confinement of cobalt porphyrins in the PCN-224 metal-organic framework leads to an enhanced selectivity towards HO and stability of the catalyst.

On the structural evolution of nanoporous optically transparent CuO photocathodes upon calcination for photoelectrochemical applications.

Copper oxides are promising photocathode materials for solar hydrogen production due to their narrow optical band gap energy allowing broad visible light absorption. However, they suffer from severe photocorrosion upon illumination, mainly due to copper reduction. Nanostructuring has been proven to enhance the photoresponse of CuO photocathodes; however, there is a lack of precise structural control on the nanoscale upon sol-gel synthesis and calcination for achieving optically transparent CuO thin film photoabsorbers.

Resolving a structural issue in cerium-nickel-based oxide: a single compound or a two-phase system?

CeNiO has been reported in the literature in the last few years as a novel LnNiO compound with promising applications in different catalytic fields, but its structure has not been correctly reported so far. In this research, CeNiO (RB1), CeO and NiO have been synthesized in a nanocrystalline form using a modified citrate aqueous sol-gel route. A direct comparison between the equimolar physical mixture ((CeO) : (NiO) = 1 : 1) and compound RB1 was made.

Coordinative Stabilization of Single Bismuth Sites in a Carbon-Nitrogen Matrix to Generate Atom-Efficient Catalysts for Electrochemical Nitrate Reduction to Ammonia.

Electrochemical nitrate reduction to ammonia powered by renewable electricity is not only a promising alternative to the established energy-intense and non-ecofriendly Haber-Bosch reaction for ammonia generation but also a future contributor to the ever-more important denitrification schemes. Nevertheless, this reaction is still impeded by the lack of understanding for the underlying reaction mechanism on the molecular scale which is necessary for the rational design of active, selective, and stable electrocatalysts. Herein, a novel single-site bismuth catalyst (Bi-N-C) for nitrate electroreduction is reported to produce ammonia with maximum Faradaic efficiency of 88.

A facile strategy for reclaiming discarded graphite and harnessing the rate capabilities of graphite anodes.

Graphite negative electrodes are unbeaten hitherto in lithium-ion batteries (LiBs) due to their unique chemical and physical properties. Thus, the increasing scarcity of graphite resources makes smart recycling or repurposing of discarded graphite particularly imperative. However, the current recycling techniques still need to be improved upon with urgency.

Anomalous Glide Plane in Platinum Nano- and Microcrystals.

At the nanoscale, the properties of materials depend critically on the presence of crystal defects. However, imaging and characterizing the structure of defects in three dimensions inside a crystal remain a challenge. Here, by using Bragg coherent diffraction imaging, we observe an unexpected anomalous {110} glide plane in two Pt submicrometer crystals grown by very different processes and having very different morphologies.

Mesoporous CuFe O Photoanodes for Solar Water Oxidation: Impact of Surface Morphology on the Photoelectrochemical Properties.

Metal oxide-based photoelectrodes for solar water splitting often utilize nanostructures to increase the solid-liquid interface area. This reduces charge transport distances and increases the photocurrent for materials with short minority charge carrier diffusion lengths. While the merits of nanostructuring are well established, the effect of surface order on the photocurrent and carrier recombination has not yet received much attention in the literature.

Electroreduction of CO on Au(310)@Cu High-index Facets.

The chemical selectivity and faradaic efficiency of high-index Cu facets for the CO reduction reaction (CO RR) is investigated. More specifically, shape-controlled nanoparticles enclosed by Cu {hk0} facets are fabricated using Cu multilayer deposition at three distinct layer thicknesses on the surface facets of Au truncated ditetragonal nanoprisms (Au DTPs). Au DTPs are shapes enclosed by 12 high-index {310} facets.

Sol-Gel-Derived Ordered Mesoporous High Entropy Spinel Ferrites and Assessment of Their Photoelectrochemical and Electrocatalytic Water Splitting Performance.

The novel material class of high entropy oxides with their unique and unexpected physicochemical properties is a candidate for energy applications. Herein, it is reported for the first time about the physico- and (photo-) electrochemical properties of ordered mesoporous (CoNiCuZnMg)Fe O thin films synthesized by a soft-templating and dip-coating approach. The A-site high entropy ferrites (HEF) are composed of periodically ordered mesopores building a highly accessible inorganic nanoarchitecture with large specific surface areas.

Single-Source-Precursor Derived Transition Metal Alloys Embedded in Nitrogen-Doped Porous Carbons as Efficient Oxygen Evolution Electrocatalysts.

Carbon supported metallic nanomaterials are of great interest due to their low-cost, high durability and promising functional performance. Herein, a highly active oxygen evolution reaction (OER) electrocatalyst comprised of defective carbon shell encapsulated metal (Fe, Co, Ni) nanoparticles and their alloys supported on in-situ formed N-doped graphene/carbon nanotube hybrid is synthesized from novel single-source-precursors (SSP). The precursors are synthesized by a facile one-pot reaction of tannic acid with polyethylenimine and different metal ions and subsequent pyrolysis of the SSP.

P-Terminated InP (001) Surfaces: Surface Band Bending and Reactivity to Water.

Stable InP (001) surfaces are characterized by fully occupied and empty surface states close to the bulk valence and conduction band edges, respectively. The present photoemission data show, however, a surface Fermi level pinning only slightly below the midgap energy which gives rise to an appreciable surface band bending. By means of density functional theory calculations, it is shown that this apparent discrepancy is due to surface defects that form at finite temperature.

Shedding Light on Solid Sorbents: Evaluation of Supported Potassium Carbonate Particle Size and Its Effect on CO Capture from Air.

Solid sorbents are essential for developing technologies that directly capture CO from air. In solid sorbents, metal oxides and/or alkali metal carbonates such as potassium carbonate (KCO) are promising active components owing to their high thermal stability, low cost, and ability to chemisorb the CO present at low concentrations in air. However, this chemisorption process is likely limited by internal diffusion of CO into the bulk of KCO.

Electrochemical Generation of Catalytically Active Edge Sites in C N-Type Carbon Materials for Artificial Nitrogen Fixation.

The electrochemical nitrogen reduction reaction (NRR) to ammonia (NH ) is a potentially carbon-neutral and decentralized supplement to the established Haber-Bosch process. Catalytic activation of the highly stable dinitrogen molecules remains a great challenge. Especially metal-free nitrogen-doped carbon catalysts do not often reach the desired selectivity and ammonia production rates due to their low concentration of NRR active sites and possible instability of heteroatoms under electrochemical potential, which can even contribute to false positive results.

A Selective Copper Based Oxygen Reduction Catalyst for the Electrochemical Synthesis of HO at Neutral pH.

HO is a bulk chemical used as "green" alternative in a variety of applications, but has an energy and waste intensive production method. The electrochemical O reduction to HO is viable alternative with examples of the direct production of up to 20% HO solutions. In that respect, we found that the dinuclear complex Cu(btmpa) (6,6'-bis[[bis(2-pyridylmethyl)amino]methyl]-2,2'-bipyridine) reduces O to HO with a selectivity up to 90 % according to single linear sweep rotating ring disk electrode measurements.

A Heterogenized Copper Phenanthroline System to Catalyze the Oxygen Reduction Reaction.

Upon the electrochemical reduction of an in situ generated 5-diazo-1,10-phenanthroline ion, phenanthroline was covalently attached to a gold electrode. The grafted molecules act as a ligand when brought in contact with a copper-containing electrolyte solution. As the ligands are limited in spatial movement, the exclusive formation of the active species with only one phenanthroline ligand coordinated was expected.

Imaging the facet surface strain state of supported multi-faceted Pt nanoparticles during reaction.

Nanostructures with specific crystallographic planes display distinctive physico-chemical properties because of their unique atomic arrangements, resulting in widespread applications in catalysis, energy conversion or sensing. Understanding strain dynamics and their relationship with crystallographic facets have been largely unexplored. Here, we reveal in situ, in three-dimensions and at the nanoscale, the volume, surface and interface strain evolution of single supported platinum nanocrystals during reaction using coherent x-ray diffractive imaging.

On the Homogeneity of a Cobalt-Based Water Oxidation Catalyst.

The homogeneity of molecular Co-based water oxidation catalysts (WOCs) has been a subject of debate over the last 10 years as assumed various homogeneous Co-based WOCs were found to actually form CoO under operating conditions. The homogeneity of the Co(H) (H = ,-bis(2,2'-bipyrid-6-yl)amine) system was investigated with cyclic voltammetry, electrochemical quartz crystal microbalance, and X-ray photoelectron spectroscopy. The obtained experimental results were compared with heterogeneous CoO .

Predoped Oxygenated Defects Activate Nitrogen-Doped Graphene for the Oxygen Reduction Reaction.

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.

Twin boundary migration in an individual platinum nanocrystal during catalytic CO oxidation.

At the nanoscale, elastic strain and crystal defects largely influence the properties and functionalities of materials. The ability to predict the structural evolution of catalytic nanocrystals during the reaction is of primary importance for catalyst design. However, to date, imaging and characterising the structure of defects inside a nanocrystal in three-dimensions and in situ during reaction has remained a challenge.

On the Contact Optimization of ALD-Based MoS FETs: Correlation of Processing Conditions and Interface Chemistry with Device Electrical Performance.

Despite the extensive ongoing research on MoS field effect transistors (FETs), the key role of device processing conditions in the chemistry involved at the metal-to-MoS interface and their influence on the electrical performance are often overlooked. In addition, the majority of reports on MoS contacts are based on exfoliated MoS, whereas synthetic films are even more susceptible to the changes made in device processing conditions. In this paper, working FETs with atomic layer deposition (ALD)-based MoS films and Ti/Au contacts are demonstrated, using current-voltage (-) characterization.

Facet-Dependent Strain Determination in Electrochemically Synthetized Platinum Model Catalytic Nanoparticles.

Studying model nanoparticles is one approach to better understand the structural evolution of a catalyst during reactions. These nanoparticles feature well-defined faceting, offering the possibility to extract structural information as a function of facet orientation and compare it to theoretical simulations. Using Bragg Coherent X-ray Diffraction Imaging, the uniformity of electrochemically synthesized model catalysts is studied, here high-index faceted tetrahexahedral (THH) platinum nanoparticles at ambient conditions.