The activation of dioxygen for selective oxidation of organic molecules is a major catalytic challenge. Inspired by the activity of nitrogen-doped carbons in electrocatalytic oxygen reduction, we combined such a carbon with metal-oxide catalysts to yield cooperative catalysts. These simple materials boost the catalytic oxidation of several alcohols, using molecular oxygen at atmospheric pressure and low temperature (80 °C). Cobalt and copper oxide demonstrate the highest activities. The high activity and selectivity of these catalysts arises from the cooperative action of their components, as proven by various control experiments and spectroscopic techniques. We propose that the reaction should not be viewed as occurring at an 'active site', but rather at an 'active doughnut'-the volume surrounding the base of a carbon-supported metal-oxide particle.

To effectively manipulate the electronic structure of the catalysts, we present here a simple bottom-up synthesis protocol for agglomerating palladium and cuprous oxide ultrasmall nanoclusters into single nanoparticles, forming so-called quantum dot assemblies (QDAs). Our synthesis is based on the galvanic displacement of copper with palladium cations under O2-free conditions, rendering the simultaneous and unique crystal growth of ∼3 nm Cu2O and Pd clusters. Such assemblies, comprising ultrasmall nanoconstitutes, offer much more phase boundaries, where the interfacial electronic effect becomes prominent in catalysis. This is demonstrated in the electrocatalytic oxidation of formaldehyde, ethanol, and glucose. In all three cases, the QDA catalyst, despite its similar Pd loading, outperforms the monometallic palladium catalyst. Indeed, complementing the experimental results with density functional theory calculations, we could confirm the sharply increased charge density at the Pd–Cu heterojunction and the decreased energy barrier of the formaldehyde oxidation on the QDA catalyst. Finally, we applied these catalysts in electroless copper deposition – an industrially relevant process for manufacturing printed circuit boards. The QDA catalysts gave uniform and robust copper wires at a rate that was three times faster than that of the monometallic Pd catalyst, showing their potential for real-life applications.