Na-Promoted Bimetallic Hydroxide Nanoparticles for Aerobic C-H Activation: Catalyst Design Principles and Insights into Reaction Mechanism.

A precious metal-free bimetallic FeMn(OH) hydroxide catalyst was developed that is capable of catalyzing aerobic C-H oxidation reactions at low temperatures, without the need for an initiator, relying sustainably on molecular oxygen. Through a systematic synthetic effort, we scanned a wide nanoparticle synthesis parameter space to lay out a detailed set of catalyst design principles unraveling how the Fe/Mn cation ratio, NaOH(aq) concentration used in the synthesis, catalyst washing procedures, extent of residual Na promoters on the catalyst surface, reaction temperature, and catalyst loading influence catalytic C-H activation performance as a function of the electronic, surface chemical, and crystal structure of FeMn(OH) bimetallic hydroxide nanostructures. Our comprehensive XRD, XPS, BET, ICP-MS, H NMR, and XANES structural/product characterization results as well as mechanistic kinetic isotope effect (KIE) studies provided the following valuable insights into the molecular level origins of the catalytic performance of the bimetallic FeMn(OH) hydroxide nanostructures: (i) catalytic reactivity is due to the coexistence and synergistic operation of Fe and Mn cationic sites (with minor contributions from Fe and Mn sites) on the catalyst surface, where in the absence of one of these synergistic sites (i.

Unraveling Molecular Fingerprints of Catalytic Sulfur Poisoning at the Nanometer Scale with Near-Field Infrared Spectroscopy.

Fundamental understanding of catalytic deactivation phenomena such as sulfur poisoning occurring on metal/metal-oxide interfaces is essential for the development of high-performance heterogeneous catalysts with extended lifetimes. Unambiguous identification of catalytic poisoning species requires experimental methods simultaneously delivering accurate information regarding adsorption sites and adsorption geometries of adsorbates with nanometer-scale spatial resolution, as well as their detailed chemical structure and surface functional groups. However, to date, it has not been possible to study catalytic sulfur poisoning of metal/metal-oxide interfaces at the nanometer scale without sacrificing chemical definition.

All-Solution-Processed, Oxidation-Resistant Copper Nanowire Networks for Optoelectronic Applications with Year-Long Stability.

Copper nanowires (Cu NWs) hold promise as they possess equivalent intrinsic electrical conductivity and optical transparency to silver nanowires (Ag NWs) and cost substantially less. However, poor resistance to oxidation is the historical challenge that has prevented the large-scale industrial utilization of Cu NWs. Here, we use benzotriazole (BTA), an organic corrosion inhibitor, to passivate Cu NW networks.