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The selectivity control toward aldehyde in the aromatic alcohol oxidation remains a grand challenge using molecular oxygen under mild conditions. In this work, we designed and synthesized Pt/PCN-224(M) composites by integration of Pt nanocrystals and porphyrinic metal-organic frameworks (MOFs), PCN-224(M). The composites exhibit excellent catalytic performance in the photo-oxidation of aromatic alcohols by 1 atm O at ambient temperature, based on a synergetic photothermal effect and singlet oxygen production. Additionally, in opposition to the function of the Schottky junction, injection of hot electrons from plasmonic Pt into PCN-224(M) would lower the electron density of the Pt surface, which thus is tailorable for the optimized catalytic performance via the competition between the Schottky junction and the plasmonic effect by altering the light intensity. To the best of our knowledge, this is not only an unprecedented report on singlet oxygen-engaged selective oxidation of aromatic alcohols to aldehydes but also the first report on photothermal effect of MOFs.

Metal nanoparticles (NPs) stabilized by metal−organic frameworks (MOFs) are very promising for catalysis, while reports on their cooperative catalysis for a cascade reaction have been very rare. In this work, Pd NPs incorporated into a MOF, MIL-101, have jointly completed a tandem reaction on the basis of MOF Lewis acidity and Pd NPs. Subsequently, ultrafine PdAg alloy NPs (∼1.5 nm) have been encapsulated into MIL-101. The obtained multifunctional PdAg@MIL-101 exhibits good catalytic activity and selectivity in cascade reactions under mild conditions, on the basis of the combination of host−guest cooperation and bimetallic synergy, where MIL-101 affords Lewis acidity and Pd offers hydrogenation activity while Ag greatly improves selectivity to the target product. As far as we know, this is the first work on bimetallic NP@MOFs as multifunctional catalysts with multiple active sites (MOF acidity and bimetallic species) that exert respective functions and cooperatively catalyze a one-pot cascade reaction.

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Site-selective blocking by ALD disentangles the geometric and electronic effects of catalysts beyond the selectivity volcano.

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For TiO 2 supported Au catalysts, the Au particle size and the interfacial perimeter sites between Au particles and the TiO 2 support both play important roles in CO oxidation reaction. However, changing the Au particle size inevitably accompanied by the change of the perimeter length makes it extremely difficult to identify their individual roles. Here we reported a new strategy to isolate them by applying TiO 2 overcoat to Au/Al 2 O 3 and Au/SiO 2 catalysts using atomic layer deposition (ALD) where the new Au−TiO 2 interfacial length was precisely tuned to different degrees while preserving the particle size. High resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements of CO chemisorption all confirmed that the TiO 2 overcoat preferentially decorates the low-coordinated sites of Au nanoparticles and generates Au−TiO 2 interfaces. In CO oxidation, we demonstrated a remarkable improvement of the catalytic activities of Au/ Al 2 O 3 and Au/SiO 2 catalysts by the ALD TiO 2 overcoat. More interestingly, the activity as a function of TiO 2 ALD cycles obviously showed a volcano-like behavior, providing direct evidence that the catalytic activities of TiO 2 overcoated Au catalysts strongly correlate with the total length of perimeter sites. Finally, our work suggests that this strategy might be a new method for atomic level understanding the reaction mechanism and high performance catalyst design.

Hydrogenation of nitriles represents as an atom-economic route to synthesize amines, crucial building blocks in fine chemicals. However, high redox potentials of nitriles render this approach to produce a mixture of amines, imines and low-value hydrogenolysis byproducts in general. Here we show that quasi atomic-dispersion of Pd within the outermost layer of Ni nanoparticles to form a Pd1Ni single-atom surface alloy structure maximizes the Pd utilization and breaks the strong metal-selectivity relations in benzonitrile hydrogenation, by prompting the yield of dibenzylamine drastically from ∼5 to 97% under mild conditions (80 °C; 0.6 MPa), and boosting an activity to about eight and four times higher than Pd and Pt standard catalysts, respectively. More importantly, the undesired carcinogenic toluene by-product is completely prohibited, rendering its practical applications, especially in pharmaceutical industry. Such strategy can be extended to a broad scope of nitriles with high yields of secondary amines under mild conditions.