Carbon dioxide reduction into useful chemical products is a key technology to address urgent climate and energy challenges. In this study, a nanohybrid made by Co₃O₄ and graphene is proposed as an efficient electrocatalyst for the selective reduction of CO₂ to formate at low overpotential. The comparison between samples with different metal oxide to carbon ratio and with or without doping of the graphene moiety, indicates that the most active catalyst is formed by highly dispersed and crystalline nanocubes exposing {001} oriented surfaces, whereas the nitrogen doping is critical to obtain a controlled morphology and to facilitate a topotactic transformation during electrocatalytic conditions to CoO, which results to be the true active phase. The nanohybrid made up by intermediate loading of Co₃O₄ supported on Nitrogen doped graphene is the most active catalyst, being able to produce 3.14 mmol of formate in 8 h at -0.95 V vs SCE with a faradic efficiency of 83%.

Four novel dinuclear N-heterocyclic dicarbene gold(I) complexes with a propylene linker between the carbene moieties have been synthesized and their luminescence and electrochemical properties, together with their reactivity towards bromine oxidative addition, have been screened. All the complexes emit in the solid state in the blue-green spectral range (400–500 nm) with appreciable intensities (Φ_em up to ≈10%). In cyclic voltammetry, the Au(I)/Au(0) peak splits at low temperature into two separate peaks relative to the couples Au(I)–Au(I)/Au(I)–Au(0) and Au(I)–Au(0)/Au(0)–Au(0), thus indicating the presence of an Au⋯Au interaction in the dinuclear complex. Oxidative addition of bromine affords as a major or unique product Au(II)–Au(II) complexes most likely as a consequence of the interaction between the two gold centres favoured by the propylene linker.

An overview of the current state of mechanistic understanding of gold-catalyzed intermolecular alkyne hydrofunctionalization reactions is presented. Moving from the analysis of the main features of the by-now-generally accepted reaction mechanism, studies and evidences pointing out the mechanistic peculiarities of these reactions using different nucleophiles HNu that add to the alkyne triple bond are presented and discussed. The effects of the nature of the employed alkyne substrate and of the gold catalyst (employed ligands, counteranions, gold oxidation state), of additional additives and of the reaction conditions are also considered. Aim of this work is to provide the reader with a detailed mechanistic knowledge of this important reaction class, which will be invaluable for rapidly developing and optimizing synthetic protocols involving a gold-catalyzed alkyne hydrofunctionalization as a reaction step.