Enhanced Nitrate-to-Ammonia Efficiency over Linear Assemblies of Copper-Cobalt Nanophases Stabilized by Redox Polymers.

Renewable electricity-powered nitrate (NO ) reduction reaction (NO RR) offers a net-zero carbon route to the realization of high ammonia (NH ) productivity. However, this route suffers from low energy efficiency (EE, with a half-cell EE commonly <36%), since high overpotentials are required to overcome the weak NO binding affinity and sluggish NO RR kinetics. To alleviate this, a rational catalyst design strategy that involves the linear assembly of sub-5 nm Cu/Co nanophases into sub-20 nm thick nanoribbons is suggested.

Crystal Plane-Related Oxygen-Evolution Activity of Single Hexagonal Co O Spinel Particles.

The electrocatalytic activity for the oxygen evolution reaction in alkaline electrolyte of hexagonal spinel Co O nanoparticles derived using scanning electrochemical cell microscopy (SECCM) is correlated with scanning electron microscopy and atomic force microscopy images of the droplet landing sites. A unique way to deconvolute the intrinsic catalytic activity of individual crystal facets of the hexagonal Co O spinel particle is demonstrated in terms of the turnover frequency (TOF) of surface Co atoms. The top surface exposing 111 crystal planes displayed a thickness-dependent TOF with a TOF of about 100 s at a potential of 1.

Revealing the Heterogeneity of Large-Area MoS Layers in the Electrocatalytic Hydrogen Evolution Reaction.

The electrocatalytic activity concerning the hydrogen evolution reaction (HER) of micrometer-sized MoS layers transferred on a glassy carbon surface was evaluated by scanning electrochemical cell microscopy (SECCM) in a high-throughput approach. Multiple areas on single or multiple MoS layers were assessed using a hopping mode nanocapillary positioning with a hopping distance of 500 nm and a nanopipette size of around 55 nm. The locally recorded linear sweep voltammograms revealed a high lateral heterogeneity over the MoS sheet regarding their HER activity, with currents between -40 and -60 pA recorded at -0.

Splicing the active phases of copper/cobalt-based catalysts achieves high-rate tandem electroreduction of nitrate to ammonia.

Electrocatalytic recycling of waste nitrate (NO) to valuable ammonia (NH) at ambient conditions is a green and appealing alternative to the Haber-Bosch process. However, the reaction requires multi-step electron and proton transfer, making it a grand challenge to drive high-rate NH synthesis in an energy-efficient way. Herein, we present a design concept of tandem catalysts, which involves coupling intermediate phases of different transition metals, existing at low applied overpotentials, as cooperative active sites that enable cascade NO-to-NH conversion, in turn avoiding the generally encountered scaling relations.

Single Particle Nanoelectrochemistry Reveals the Catalytic Oxygen Evolution Reaction Activity of Co O Nanocubes.

Co O nanocubes are evaluated concerning their intrinsic electrocatalytic activity towards the oxygen evolution reaction (OER) by means of single-entity electrochemistry. Scanning electrochemical cell microscopy (SECCM) provides data on the electrocatalytic OER activity from several individual measurement areas covering one Co O nanocube of a comparatively high number of individual particles with sufficient statistical reproducibility. Single-particle-on-nanoelectrode measurements of Co O nanocubes provide an accelerated stress test at highly alkaline conditions with current densities of up to 5.

A hybrid hydrazine redox flow battery with a reversible electron acceptor.

Hydrazine is a pollutant with high hydrogen content, offering tremendous possibilities in a direct hydrazine fuel cell (DHFC) as it can be converted into electricity via benign end products. Due to the inner sphere nature of half-cell chemistries, hydrazine cross over triggers parasitic chemistry at the Pt-based air cathode of a state-of-the-art DHFC, overly complicating the already sluggish electrode kinetics at the positive electrode. Here, we illustrate that by altering the interfacial chemistry of the catholyte from inner sphere to outer sphere, the parasitic chemistry can be dissociated from the redox chemistry of the electron acceptor and the hybrid fuel cell can be driven by simple carbon-based cathodes.

An Electrochemical Wind Velocity Sensor.

Electrochemical interfaces invariably generate unipolar electromotive force because of the unidirectional nature of electrochemical double layers. Herein we show an unprecedented generation of a time varying bipolar electric field between identical half-cell electrodes induced by tailored interfacial migration of magnetic particles. The periodic oscillation of a bipolar electric field is monotonically correlated with velocity-dependent torque, opening new electrochemical pathways targeting velocity monitoring systems.

Fuel Exhaling Fuel Cell.

State-of-the-art proton exchange membrane fuel cells (PEMFCs) anodically inhale H fuel and cathodically expel water molecules. We show an unprecedented fuel cell concept exhibiting cathodic fuel exhalation capability of anodically inhaled fuel, driven by the neutralization energy on decoupling the direct acid-base chemistry. The fuel exhaling fuel cell delivered a peak power density of 70 mW/cm at a peak current density of 160 mA/cm with a cathodic H output of ∼80 mL in 1 h.