No abstract

In manufacturing C−N bond‐containing compounds, it is an important challenge to alternate the conventional methodologies that utilize reactive substrates, toxic reagents, and organic solvents. In this study, we developed an electrochemical method to synthesize a C−N bond‐containing molecule avoiding the use of cyanides and amines by harnessing nitrate (NO3−) as a nitrogen source in an aqueous electrolyte. In addition, we utilized oxalic acid as a carbon source, which can be obtained from electrochemical conversion of CO2. Thus, our approach can provide a route for the utilization of anthropogenic CO2 and nitrate wastes, which cause serious environmental problems including global warming and eutrophication. Interestingly, the coreduction of oxalic acid and nitrate generated reactive intermediates, which led to C−N bond formation followed by further reduction to an amino acid, namely, glycine. By carefully controlling this multireduction process with a fabricated Cu–Hg electrode, we demonstrated the efficient production of glycine with a faradaic efficiency (F.E.) of up to 43.1 % at −1.4 V vs. Ag/AgCl (current density≈90 mA cm−2).

A review on manganese oxide-based electrocatalysts for the water oxidation reaction.

Electrochemical water splitting is a promising means to produce eco‐friendly hydrogen fuels. Inspired by the Mn4CaO5 cluster in nature, substantial works have been performed to develop efficient manganese (Mn)‐based heterogeneous catalysts. Despite improvements in catalytic activity, the underlying mechanism of the oxygen evolution reaction (OER) is not completely elucidated owing to the lack of direct spectroscopic evidence for the active Mn‐oxo moieties. We identify water oxidation intermediates on the surface of Mn3O4 nanoparticles (NPs) in the OER at neutral pH by in situ Raman spectroscopy. A potential‐dependent Raman peak was detected at 760 cm−1 and assigned to the active MnIV=O species generated during water oxidation. Isotope‐labeling experiments combined with scavenger experiments confirmed the generation of surface terminal MnIV=O intermediates in the Mn‐oxide NPs. This study provides an insight into the design of systems for the observation of reaction intermediates.