Thiol Functionalised Supports for Controlled Metal Nanoparticle Formation for Improved C-C Coupling.

The myriad applications of metal nanoparticle systems have individual demands on their size, shape and electronic states, demanding novel synthetic methods to optimise these properties. Herein we report our method of exploiting strong thiol-Pd binding as a precursor for forming small, uniform Pd nanoparticles on activation. We validate our approach with a range of characterisation techniques and contrast our design strategy with an analogous wetness impregnation method, showing the drastic improvements for catalytic C-C coupling. The presence of the thiol groups offers greater control over nanoparticle formation, particularly temperature resolution on activation, potentially allowing more targeted nanoparticle formation procedures.

Bimetallic PdAu Catalysts within Hierarchically Porous Architectures for Aerobic Oxidation of Benzyl Alcohol.

Hierarchically porous (HP) zeotype materials (possessing both micropores and mesopores) offer improved diffusional access to intra-framework active sites, analogous to mesoporous materials, yet retain the high selectivity of the microporous (MP) bulk. We have recently designed crystalline hierarchically porous silicoaluminophosphates (SAPOs) with enhanced mass-transport characteristics, which can lead to significant improvement in catalytic activity and catalyst lifetime. In this study, we have prepared PdAu bimetallic nanostructures supported on HP-SAPO frameworks by an incipient impregnation of metal precursors followed by H2 reduction at 300 °C, for the aerobic oxidation of benzyl alcohol to benzaldehyde. PdAu NPs supported on HP framework displayed significantly enhanced catalytic activities, when compared with their MP analogues, clearly highlighting the benefits of introducing hierarchical porosity in the SAPO support matrix.

Exploring the origins of crystallisation kinetics in hierarchical materials using in situ X-ray diffraction and pair distribution function analysis.

The discovery of novel catalytic materials is predicated on understanding contemporary synthetic processes. With this fundamental knowledge in place it becomes possible to modify the final material with subtle changes to the synthesis process. In this vein, hierarchical materials, formed by the addition of a mesoporogen within the hydrothermal synthesis, have attracted a significant amount of attention due to their catalytic benefits over analogous microporous species. In this work we monitor the hydrothermal synthesis in situ of a hierarchical and a microporous aluminophosphate, for the first time, combining total scattering and pairwise distribution function data. In doing so we observe the local formation of the species, and the longer range crystallisation processes concurrently.

The influence of porosity on nanoparticle formation in hierarchical aluminophosphates.

In this work we explore the deposition of gold onto a silicoaluminophosphate, using a variety of known nanoparticle deposition techniques. By comparing the gold particles deposited on a traditional microporous aluminophosphate, with an analogous hierarchical species, containing both micropores and mesopores, we explore the influence of this dual porosity on nanoparticle deposition. We show that the presence of mesopores has limited influence on the nanoparticle properties, but allows the system to maintain porosity after nanoparticle deposition. This will aid diffusion of reagents through the system, allowing continued access to the active sites in hierarchical systems, which offers significant potential in catalytic oxidation/reduction reactions.