Al2 O3 -Stabilized Pt Nanozymes: Peroxidase Mimetics and Application in Glucose Detection.

As promising alternatives for natural enzymes, much attention has been paid to nanozymes. And our recent study showed that the medium acid sites on the support are the active sites for the adsorption and oxidation of the substrate. Thus, in this work, due to the abundance of medium acid sites, Al2 O3 was chosen as the support to prepare Pt/Al2 O3 nanozymes. Through the Pt/Al2 O3 samples, we further proved that the distribution of the Pt clusters and the amount of the medium acid sites can significantly influence the peroxidase-like activity. Then the Pt/Al2 O3 sample was used for the detection of glucose. And as low as 0.96 µM glucose could be detected with a linear range from 5-60 µM via our method. This work showed the great potential applications of the easily prepared Pt/Al2 O3 samples in varieties of simple, robust, and easy-to-make analytical approaches in the future.

Atomic Insights into Synergistic Nitroarene Hydrogenation over Nanodiamond-Supported Pt1 -Fe1 Dual-Single-Atom Catalyst.

Fundamental understanding of the synergistic effect of bimetallic catalysts is of extreme significance in heterogeneous catalysis, but a great challenge lies in the precise construction of uniform dual-metal sites. Here, we develop a novel method for constructing Pt1 -Fe1 /ND dual-single-atom catalyst, by anchoring Pt single atoms on Fe1 -N4 sites decorating a nanodiamond (ND) surface. Using this catalyst, the synergy of nitroarenes selective hydrogenation is revealed. In detail, hydrogen is activated on the Pt1 -Fe1 dual site and the nitro group is strongly adsorbed on the Fe1 site via a vertical configuration for subsequent hydrogenation. Such synergistic effect decreases the activation energy and results in an unprecedented catalytic performance (3.1 s-1 turnover frequency, ca. 100 % selectivity, 24 types of substrates). Our findings advance the applications of dual-single-atom catalysts in selective hydrogenations and open up a new way to explore the nature of synergistic catalysis at the atomic level.

A Manganese-Based Metal-Organic Framework as a Cold-Adapted Nanozyme.

The development of cold-adapted enzymes with high efficiency and good stability is an advanced strategy to overcome the limitations of catalytic medicine in low and cryogenic temperatures. In this work, inspired by natural enzymes, a novel cold-adapted nanozyme based on a manganese-based nanosized metal-organic framework (nMnBTC) is designed and synthesized. The nMnBTC as an oxidase mimetic not only exhibits excellent activity at 0 °C, but also presents almost no observable activity loss as the temperature is increased to 45 °C. This breaks the traditional recognition that enzymes show maximum activity only under specific psychrophilic or thermophilic condition. The superior performance of nMnBTC as a cold-adapted nanozyme can be attributed to its high-catalytic efficiency at low temperature, good substrate affinity, and flexible conformation. Based on the robust performance of nMnBTC, a low-temperature antiviral strategy is developed to inactivate influenza virus H1N1 even at -20 °C. These results not only provide an important guide for the rational design of highly efficient artificial cold-adapted enzymes, but also pave a novel way for biomedical application in cryogenic fields.

Rhodium nanoparticles confined in titania nanotubes for efficient Hydrogen evolution from Ammonia Borane.

Designing efficient catalysts for hydrogen evolution from hydrolysis of ammonia borane (AB) have attracted considerable attention. Rhodium (Rh) based catalysts with rational design present remarkable catalytic performance for the reaction. Herein, we report the confined Rh@TiO2 catalysts synthesized by atomic layer deposition combining with the sacrificial template approach, in which the Rh nanoparticles are uniformly confined on the inner surface of the porous titania nanotubes. The optimized catalysts show high catalytic activity with a turnover frequency value of 334.1 molH2·molRh-1·min-1 and better durability. Mechanistic investigation demonstrates that the cleavage of OH bands in water should be the rate determining step, and the appropriate concentration of NaOH can further enhance the hydrogen evolution activity. The catalysts can also achieve the hydrogenation of various organic substrates using AB as the hydrogen source. In addition, our present strategy is general and can be extended to the synthesis of other confined catalysts for various catalytic reactions.

Porous TiO2 Nanotubes with Spatially Separated Platinum and CoOx Cocatalysts Produced by Atomic Layer Deposition for Photocatalytic Hydrogen Production.

Efficient separation of photogenerated electrons and holes, and associated surface reactions, is a crucial aspect of efficient semiconductor photocatalytic systems employed for photocatalytic hydrogen production. A new CoOx /TiO2 /Pt photocatalyst produced by template-assisted atomic layer deposition is reported for photocatalytic hydrogen production on Pt and CoOx dual cocatalysts. Pt nanoclusters acting as electron collectors and active sites for the reduction reaction are deposited on the inner surface of porous TiO2 nanotubes, while CoOx nanoclusters acting as hole collectors and active sites for oxidation reaction are deposited on the outer surface of porous TiO2 nanotubes. A CoOx /TiO2 /Pt photocatalyst, comprising ultra-low concentrations of noble Pt (0.046 wt %) and CoOx (0.019 wt %) deposited simultaneously with one atomic layer deposition cycle, achieves remarkably high photocatalytic efficiency (275.9 µmol h-1 ), which is nearly five times as high as that of pristine TiO2 nanotubes (56.5 µmol h-1 ). The highly dispersed Pt and CoOx nanoclusters, porous structure of TiO2 nanotubes with large specific surface area, and the synergetic effect of the spatially separated Pt and CoOx dual cocatalysts contribute to the excellent photocatalytic activity.

Ultrathin Coating of Confined Pt Nanocatalysts by Atomic Layer Deposition for Enhanced Catalytic Performance in Hydrogenation Reactions.

Metal-support interfaces play a prominent role in heterogeneous catalysis. However, tailoring the metal-support interfaces to realize full utilization remains a major challenge. In this work, we propose a graceful strategy to maximize the metal-oxide interfaces by coating confined nanoparticles with an ultrathin oxide layer. This is achieved by sequential deposition of ultrathin Al2 O3 coats, Pt, and a thick Al2 O3 layer on carbon nanocoils templates by atomic layer deposition (ALD), followed by removal of the templates. Compared with the Pt catalysts confined in Al2 O3 nanotubes without the ultrathin coats, the ultrathin coated samples have larger Pt-Al2 O3 interfaces. The maximized interfaces significantly improve the activity and the protecting Al2 O3 nanotubes retain the stability for hydrogenation reactions of 4-nitrophenol. We believe that applying ALD ultrathin coats on confined catalysts is a promising way to achieve enhanced performance for other catalysts.

A Tandem Catalyst with Multiple Metal Oxide Interfaces Produced by Atomic Layer Deposition.

Ideal heterogeneous tandem catalysts necessitate the rational design and integration of collaborative active sites. Herein, we report on the synthesis of a new tandem catalyst with multiple metal-oxide interfaces based on a tube-in-tube nanostructure using template-assisted atomic layer deposition, in which Ni nanoparticles are supported on the outer surface of the inner Al2 O3 nanotube (Ni/Al2 O3 interface) and Pt nanoparticles are attached to the inner surface of the outer TiO2 nanotube (Pt/TiO2 interface). The tandem catalyst shows remarkably high catalytic efficiency in nitrobenzene hydrogenation over Pt/TiO2 interface with hydrogen formed in situ by the decomposition of hydrazine hydrate over Ni/Al2 O3 interface. This can be ascribed to the synergy effect of the two interfaces and the confined nanospace favoring the instant transfer of intermediates. The tube-in-tube tandem catalyst with multiple metal-oxide interfaces represents a new concept for the design of highly efficient and multifunctional nanocatalysts.