C–N cross-coupling is one of the most valuable and widespread transformations in organic synthesis. Largely dominated by Pd- and Cu-based catalytic systems, it has proven to be a staple transformation for those in both academia and industry. The current study presents the development and mechanistic understanding of an electrochemically driven, Ni-catalyzed method for achieving this reaction of high strategic importance. Through a series of electrochemical, computational, kinetic, and empirical experiments, the key mechanistic features of this reaction have been unraveled, leading to a second generation set of conditions that is applicable to a broad range of aryl halides and amine nucleophiles including complex examples on oligopeptides, medicinally relevant heterocycles, natural products, and sugars. Full disclosure of the current limitations and procedures for both batch and flow scale-ups (100 g) are also described.

A range of electroanalytical tools can be applied to studying redox reactions, probing key mechanistic questions in synthetic chemistry.

Scanning electrochemical microscopy (SECM) is a powerful tool for mapping surface reactivity. Electrochemical mapping of electrocatalytic processes at the nanoscale is, however, challenging because the surface of a nanoelectrode tip is easily fouled by impurities and/or deactivated by products and intermediates of innersphere surface reactions. To overcome this difficulty, we introduce new types of SECM nanotips based on bimolecular electron transfer between the dissolved electroactive species and a redox mediator attached to the surface of a carbon nanoelectrode. A tris(2,2′-bipyridine)ruthenium complex, Ru(bpy) 3 , that undergoes reversible oxidation/reduction reactions at both positive and negative potentials was used to prepare the SECM nanoprobes for mapping a wide range of electrocatalytic processes through oxidation of H 2 , reduction of O 2 , and both oxidation and reduction of H 2 O 2 at the tip. In addition to high-resolution reactivity mapping and localized kinetic measurements, chemically modified nanoelectrodes can serve as nanosensors for a number of important analytes such as reactive oxygen and nitrogen species and neurotransmitters.

Electrochemical processes occurring at solid/solid and solid/membrane interfaces govern the behavior of a variety of energy storage devices, including electrocatalytic reactions at electrode/membrane interfaces in fuel cells and ion insertion at electrode/electrolyte interfaces in solid-state batteries. Due to the heterogeneity of these systems, interrogation of interfacial activity at nanometer length scales is desired to understand system performance, yet the buried nature of the interfaces makes localized activity inaccessible to conventional electrochemical techniques. Herein, we demonstrate nanoscale electrochemical imaging of hydrogen evolution at individual Pt nanoparticles (PtNPs) positioned at a buried interface using scanning electrochemical cell microscopy (SECCM). Specifically, we image the hydrogen evolution reaction (HER) at individual carbon-supported PtNP electrocatalysts covered by a 100 to 800 nm thick layer of the proton exchange membrane Nafion. The rate of hydrogen evolution at PtNP at this buried interface is shown to be a function of Nafion thickness, with the highest activity observed for ∼200 nm thick films.

A silver nanoparticle immobilized penicillamine self-assembled electrode, AgNPs–PCA–Au, can simultaneously sense dopamine, epinephrine, ascorbic acid and uric acid at neutral pH.