Traditionally, supported metal catalysts have been synthesized by reduction of precursors directly over the support. In these techniques, it is challenging to control the metal cluster size, composition and crystal structure. Herein, we have developed a novel approach to design catalysts with controlled morphologies by infusing presynthesized nanocrystals into the supports. High surface area mesoporous materials, including graphitic carbons, have been utilized for obtaining a high degree of metal dispersion to enhance catalyst stabilities and activities. Gold and iridium nanocrystals have been infused in mesoporous silica with loadings up to 2 wt % using supercritical CO₂ as an antisolvent in toluene to enhance the van der Waals interactions between nanocrystals and the silica. The iridium catalysts show high catalytic activity and do not require high temperature annealing for ligand removal, as ligands bind weakly to the iridium surface. To further enhance metal loadings to >10 % in the catalysts, short-ranged interactions between the metal nanocrystals and the support are further strengthened with weakly binding ligands to expose more of the metal surface to the support. For pre-synthesized FePt nanocrystals, coated with oleic acid and oleylamine ligands, high loadings >10 wt % in mesoporous silica are achieved, without using CO₂. The strong metal-support interactions favor FePt adsorption on the support and also enhance stability against sintering at high temperatures. High resistance to sintering favors formation of the FePt intermetallic crystal structure with <4 nm size upon thermal annealing at 700 °C. The fundamental understanding of the metal-support interactions gained from these studies is then utilized in the design of highly stable Pt and Pt-Cu electrocatalysts with controlled size, composition and alloy structure supported on graphitized mesoporous carbons for oxygen reduction. The resistance of the graphitic carbons to oxidation coupled with strong metal-support interactions mitigate nanoparticle isolation from the support, nanoparticle coalescence, Pt dissolution and subsequent Ostwald ripening and thus enhance catalyst stability. The control of the Pt nanocrystal morphology with high concentrations of highly active (111) surface leads to 25% higher activities than commercial Pt catalysts. Furthermore, the catalyst activities obtained for Pt-Cu catalysts are 4-fold higher than Pt catalysts due to strained Pt shell generated from electrochemical dealloying of copper from the nanoparticle surface. / text

Photocatalysis is a robust synthetic tool capable of breaking and assembling chemical bonds using single electron chemistry. This is achieved through the catalytic conversion of light energy to chemical energy in situ, such that the photons being delivered are themselves reagents. Herein, an inexpensive and environmentally-benign platform for scaling up photocatalytic reaction is disclosed, harnessing blue light naturally emitted by deep-sea bioluminescent bacteria. Photobacterium angustum GB-1 was demonstrated to photoexcite both polypyridyl organometallic chromophores and organic dyes at short molecular distances, enabling photocatalysis without any external energy-consuming lamps.While improving the eco-friendliness of photocatalysis itself, we also present a method to use photocatalysis for environmental remediation. Using visible light, a nontoxic organic photosensitizer, and oxygen, we demonstrate the controlled oxidative depolymerization of polystyrene—including polystyrene retrieved from waste receptacles in Havemeyer—to acetophenone. This method is based on results obtained in the controlled aerobic deannulation of cycloalkanes, which is also discussed herein. Lastly, a means by which catalysis itself can be made more cost, resource, and time effective is presented. An innovative computational platform in development predicts new catalysts for reactions currently energetically inaccessible. In collaboration with the developers, we present experimental validation of their theoretical predictions, as well as perform the synthesis of a de novo fluorinated thiazolium precatalyst calculated to significantly lower the energetic barrier of an otherwise energetically prohibitive Stetter reaction.