No abstract

Ni(OH)2-catalyzed electrochemical oxidation of ammonia can be used for the synthesis S- or P-containing NH4NO3-based fertilizers with up to 72% faradaic efficiency and up to 98% ammonia removal efficiency.

Optimizing CO2 electrolyzer cell voltage requirement: aqueous and organic reductive electrocatalysis paired with electrooxidation of urea and ammonia.

Electrocarboxylation of organic halides represents a CO2 utilization strategy and a green alternative for the synthesis of many industrially relevant carboxylic acids. However, current electrocarboxylation methods rely on the utilization of sacrificial metal anodes, which are not sustainable, require high voltages, and complicate the understanding of the reaction mechanism. Here, we demonstrate the feasibility of performing electrocarboxylation reactions in divided cells with aqueous anolytes and nonsacrificial anodes, thereby eliminating the reliance on sacrificial anodes and opening the door for coupling of this important reduction process with various electrooxidation reactions requiring aqueous electrolytes. Specifically, we report a detailed study of electrocarboxylation of (1-bromoethyl)­benzene at a silver cathode coupled with an oxygen evolution reaction at a platinum anode in a divided cell with organic and aqueous compartments separated by ion-exchange membranes of different types. We examine how operating parameters, including membrane type, applied potential, substrate concentration, electrolyte, and temperature affect the overall process and the reaction product distribution. Based on the extensive experimental results, we propose a detailed mechanism for major electrochemical product formation accounting for both aprotic and protic environments. Systematic analysis and mechanistic insights presented in this study are expected to enable a rational catalyst, electrolyte, and system design tailored to electroorganic CO2 fixation with different organic substrates to obtain industrially relevant carboxylic acids at practical potentials and currents.

The electrochemical urea oxidation reaction (UOR) to N 2 represents an efficient route to simultaneous nitrogen removal from N-enriched waste and production of renewable fuels at the cathode. However, the overoxidation of urea to NO x À usually dominates over its oxidation to N 2 at Ni(OH) 2 -based anodes. Furthermore, detailed reaction mechanisms of UOR remain unclear, hindering the rational catalyst design. We found that UOR to NO x À on Ni(OH) 2 is accompanied by the formation of near stoichiometric amount of cyanate (NCO À ), which enabled the elucidation of UOR mechanisms. Based on our experimental and computational findings, we show that the formation of NO x À and N 2 follows two distinct vacancy-dependent pathways. We also demonstrate that the reaction selectivity can be steered towards N 2 formation by altering the composition of the catalyst, e.g., doping the catalyst with copper (Ni 0.8 Cu 0.2 (OH) 2 ) increases the faradaic efficiency of N 2 from 30 % to 55 %.

The electrochemical urea oxidation reaction (UOR) to N2 represents an efficient route to simultaneous nitrogen removal from N‐enriched waste and production of renewable fuels at the cathode. However, the overoxidation of urea to NOx− usually dominates over its oxidation to N2 at Ni(OH)2‐based anodes. Furthermore, detailed reaction mechanisms of UOR remain unclear, hindering the rational catalyst design. We found that UOR to NOx− on Ni(OH)2 is accompanied by the formation of near stoichiometric amount of cyanate (NCO−), which enabled the elucidation of UOR mechanisms. Based on our experimental and computational findings, we show that the formation of NOx− and N2 follows two distinct vacancy‐dependent pathways. We also demonstrate that the reaction selectivity can be steered towards N2 formation by altering the composition of the catalyst, e.g., doping the catalyst with copper (Ni0.8Cu0.2(OH)2) increases the faradaic efficiency of N2 from 30 % to 55 %.

Catalytic decomposition of diazomalonates and other diazoesters using Rh(II)- and Cu(II)-complexes in the presence of α,β-unsaturated δ-(N-aryl)amino esters gives rise to the formation of multi-functionalized pyrrolidines with yields of up to 82%. The reaction apparently occurs as a domino process involving the initial N-ylide formation followed by intramolecular Michael addition to the conjugated system of amino esters to afford the pyrrolidine heterocycle. The whole process can also be classified as a [4 + 1]-annulation of the δ-amino α,β-unsaturated ester with the carbenoid intermediate.

A review is given of the results of experimental studies of electron cap ture, loss and ionization in collisions of atomic species with hydrogen atoms. The results are considered in relation to current theoretical descriptions of the collision processes.