Deciphering the role of nickel in electrochemical organic oxidation reactions

Abstract

Organic oxidation reactions (OORs) powered by renewable energy sources are gaining importance as a favorable alternative to oxygen evolution reaction, with the promise of reducing the cell potential and enhancing the overall viability of the water electrolysis. This comprehensive review delves into the electrochemical oxidation of diverse organic compounds, including alcohols, aldehydes, amines, and urea, as well as biomass-derived renewable feedstocks such as hydroxymethylfurfural and glycerol. The key focus centers on the role of nickel (Ni)-based catalysts for these OORs. The unique redox activity and chemical nature of Ni have been proven instrumental for the sustainable and cost-effective oxidation of various organic molecules more efficiently and selectively. This review article discusses how strategic choices, such as the selection of foreign metals, intercalating species, vacancies, defects, and a secondary element (e.g. chalcogens and non-metals), contribute to tuning the electrochemical performances of a Ni-based (pre)catalyst for OORs. Moreover, this review provides insights into the active species in various reaction environments and further explores reaction mechanisms, to apparent phase changes of the catalyst with the most relevant examples. Finally, the review not only elucidates the limitations of the current approaches but also outlines potential avenues for future advancements in OOR.