RESUMEN
The need for effective alternative energy sources and "green" industrial processes is a more crucial societal topic than ever. In this context, mastering oxygen reduction reactions (ORRs) is a key step to develop fuel cells or to propose alternatives to energy-intensive setups such as the anthraquinone process for hydrogen peroxide production. Achieving this goal using bio-inspired metal complexes based on abundant and non-toxic elements could provide an environmentally friendly option. Given the prevalence of Cu-containing active sites capable of reductive activation of dioxygen in nature, the development of Cu-based catalysts for the ORR thus appears to be a relevant approach. We herein report the preparation, full characterization and (TD)DFT investigation of a new dinuclear mixed-valent copper complex 6 exhibiting a Cu2S core and a bridging triflate anion. Its ORR activity was compared with that of its parent catalyst 1. Two types of solvents were used, acetonitrile and acetone, and various catalyst/Me8Fc (electron source) ratios were tested. Our results highlight a counterintuitive solvent effect for 1 and a drastic drop in the activity for 6 in coordinating acetonitrile together with the modification of its chemical structure.
RESUMEN
Inspection of Oxygen Reduction Reactions (ORRs) using a mixed-valent Cu2S complex as a pre-catalyst revealed a tuneable H2O2vs. H2O production under mild conditions by controlling the amount of sacrificial reducer. The fully reduced bisCuI state is the main active species in solution, with fast kinetics. This new catalytic system is robust for H2O2 production with several cycles achieved and opens up perspectives for integration into devices.
RESUMEN
We demonstrate, based on experimental and theoretical evidence, that the isolated [2(CH3 CN)2 ]2+ complex prepared in CH3 CN and containing a mixed-valent {Cu2II,I S} core evolves towards a new [2(CH3 CN)3 ]2+ species upon solvation in CH3 CN. Unlike its typeâ III structural analogue [2(H2 O)(OTf)]+ active toward N2 O reduction, this new typeâ I compound is inactive. This outcome opens new perspectives for a rational for N2 O activation using bio-inspired Cu/S complexes, especially on the role of the valence localization/delocalization and the Cu-Cu bond on the reactivity.