Boosting the sintering resistance of platinum-alumina catalyst via a morphology-confined phosphate doping strategy

It is still a great challenge to develop robust sintering-resistant automotive exhaust catalysts due to the harsh working temperature varying from ambient to >1000 °C. Here we report a strategy...

β-Cyclodextrin-Silica Hybrid: A Spatially Controllable Anchoring Strategy for Cu(II)/Cu(I) Complex Immobilization

The development of new strategies for spatially controllable immobilization has encouraged the preparation of novel catalysts based on the organic-inorganic hybrid concept. In the present paper, a Cu-based multi-structured silica catalyst has been prepared and fully characterized. The inclusion of Cu(II) in β-cyclodextrins has been exploited with the double aim to stabilize the metal and to act as a source of Cu(I) catalytic sites. Multi-technique characterization by infrared, UV-visible, electron microscopy and X-ray absorption spectroscopies of the fresh and exhaust catalysts provided information on the local structure, redox properties and stability of the investigated hybrid systems. The catalytic system showed that copper nanospecies were dispersed on the support and hardly affected by the catalytic tests, confirming the stabilizing effect of β-CD, and likely of the N1-(3-Trimethoxysilylpropyl) diethylenetriamine spacer, as deduced by X-ray absorption spectroscopy analysis. Overall, we demonstrate a feasible approach to efficiently anchor Cu(II) species and to obtain a reusable single-site hybrid catalyst well suited for Cu(I)-catalyzed alkyne-azide cycloaddition.

Activation of subnanometric Pt on Cu-modified CeO2 via redox-coupled atomic layer deposition for CO oxidation

Improving the low-temperature activity (below 100 °C) and noble-metal efficiency of automotive exhaust catalysts has been a continuous effort to eliminate cold-start emissions, yet great challenges remain. Here we report a strategy to activate the low-temperature performance of Pt catalysts on Cu-modified CeO2 supports based on redox-coupled atomic layer deposition. The interfacial reducibility and structure of composite catalysts have been precisely tuned by oxide doping and accurate control of Pt size. Cu-modified CeO2-supported Pt sub-nanoclusters demonstrate a remarkable performance with an onset of CO oxidation reactivity below room temperature, which is one order of magnitude more active than atomically-dispersed Pt catalysts. The Cu-O-Ce site with activated lattice oxygen anchors deposited Pt sub-nanoclusters, leading to a moderate CO adsorption strength at the interface that facilitates the low-temperature CO oxidation performance.