Enhanced Photobiocatalytic Cascades at Pickering Droplet Interfaces.

Developing new methods to engineer photobiocatalytic reactions is of utmost significance for artificial photosynthesis, but it remains a grand challenge due to the intrinsic incompatibility of biocatalysts with photocatalysts. In this work, photocatalysts and enzymes were spatially colocalized at Pickering droplet interfaces, where the reaction microenvironment and the spatial distance between two distinct catalysts were exquisitely regulated to achieve unprecedented photobiocatalytic cascade reactions. As proof of the concept, ultrathin graphitic carbon nitride nanosheets loaded with Au nanoparticles were precisely positioned in the outer interfacial layer of Pickering oil droplets to produce HO under light irradiation, while enzymes were exactly placed in the inner interfacial layer to catalyze the subsequent biocatalytic oxidation reactions using in situ formed HO as an oxidant.

Amphiphilic Covalent Organic Framework Nanoparticles for Pickering Emulsion Catalysis with Size Selectivity.

Exploiting advanced amphiphilic solid catalysts is crucial to the development of Pickering emulsion catalysis. Herein, covalent organic framework (COF) nanoparticles constructed with highly hydrophobic monomers as linkers were found to show superior amphiphilicity and they were then developed as a new class of solid emulsifiers for Pickering emulsion catalysis. Employing amphiphilic COFs as solid emulsifiers, Pickering emulsions with controllable emulsion type and droplet sizes were obtained.

Spatial Localization of Two Enzymes at Pickering Emulsion Droplet Interfaces for Cascade Reactions.

Developing biocatalytic cascades in abiological conditions is of utmost significance, but such processes often suffer from low reaction efficiency because of incompatible reaction environments and suppressed intermediate transportation. Herein we report a new type of biocatalytic cascade by localizing two different enzymes separately in the outer and inner interfacial layers of Pickering emulsion droplets. This versatile approach enables the localization of two enzymes in their preferred reaction microenvironments and simultaneously in nanoscale proximity of each other.

Boosting Catalytic Selectivity through a Precise Spatial Control of Catalysts at Pickering Droplet Interfaces.

Exploration of new methodologies to tune catalytic selectivity is a long-sought goal in catalytic community. In this work, oil-water interfaces of Pickering emulsions are developed to effectively regulate catalytic selectivity of hydrogenation reactions, which was achieved via a precise control of the spatial distribution of metal nanoparticles at the droplet interfaces. It was found that Pd nanoparticles located in the inner interfacial layer of Pickering droplets exhibited a significantly enhanced selectivity for -chloroaniline (up to 99.

Amorphous-to-Crystalline Transformation: General Synthesis of Hollow Structured Covalent Organic Frameworks with High Crystallinity.

Morphological control of covalent organic frameworks (COFs) is particularly interesting to boost their applications; however, it remains a grand challenge to prepare hollow structured COFs (HCOFs) with high crystallinity and uniform morphology. Herein, we report a versatile and efficient strategy of amorphous-to-crystalline transformation for the general and controllable fabrication of highly crystalline HCOFs. These HCOFs exhibited ultrahigh surface areas, radially oriented nanopore channels, quite uniform morphologies, and tunable particle sizes.

Metal-Nanoparticles-Loaded Ultrathin g-CN Nanosheets at Liquid-Liquid Interfaces for Enhanced Biphasic Catalysis.

Exploiting new interface-active solid catalysts is crucial to construct efficient Pickering emulsion systems for biphasic catalysis. In this work, ultrathin g-CN nanosheets (g-CN-NSs) were developed as a new solid emulsifier to directly position catalytic sites at oil-water interfaces for improving the reaction efficiency of a biphasic reaction. Exemplified by a metal-involved biphasic reaction of nitroarenes reduction, the developed Pd/g-CN-NSs catalyst with Pd nanoparticles loaded on the surface of g-CN-NSs exhibited excellent activity with a catalytic efficiency of 1220 h.

Dual metal nanoparticles within multicompartmentalized mesoporous organosilicas for efficient sequential hydrogenation.

Controlling localization of multiple metal nanoparticles on a single support is at the cutting edge of designing cascade catalysts, but is still a scientific and technological challenge because of the lack of nanostructured materials that can not only host metal nanoparticles in different sub-compartments but also enable efficient molecular transport between different metals. Herein we report a multicompartmentalized mesoporous organosilica with spatially separated sub-compartments that are connected by short nanochannels. Such a unique structure allows co-localization of Ru and Pd nanoparticles in a nanoscale proximal fashion.

Salt of Organosilicon Framework as a Novel Emulsifier for Various Water-Oil Biphasic Systems and a Catalyst for Dibromination of Olefins in an Aqueous Medium.

Pickering emulsifiers are significant for organic reactions in an aqueous medium because they have the ability of emulsifying water-oil biphasic systems. For this reason, 2,5-bis[()-2-(triethoxysilyl)vinyl]pyridine [BTOSVP] containing a pyridine bridging group was selected as a precursor to prepare a novel salt of organosilicon framework (SOF), an amphiphilic mesoporous pyridine hydrobromide nanosphere. We first synthesized a mesoporous organosilicon framework made up of organic groups containing vinyl groups, pyridine groups, and so forth.

Mesoporous RhRu Nanosponges with Enhanced Water Dissociation toward Efficient Alkaline Hydrogen Evolution.

Lowering the energy barrier of water dissociation is critical to achieving highly efficient hydrogen evolution in alkaline conditions. Herein, we reported mesoporous RhRu nanosponges with enhanced water dissociation behavior as a new class of high-performance electrocatalysts for alkaline hydrogen evolution reaction (HER). The obtained nanosponges have a binary alloy structure (fcc) and a highly porous structure with high surface area.

Design of 3D Hollow Porous Heterogeneous Nickel-Cobalt Phosphides for Synergistically Enhancing Catalytic Performance for Electrooxidation of Methanol.

The synergistic effect among different components and the structural and morphological control of catalytic nanomaterials have attracted considerable research interest in the field of electrocatalysis, as using a rational design of the catalytic nanomaterials with the desired structure, morphology, and chemical compositions is an effective strategy for enhancing catalytic performance. Here, by changing the Ni/Co atomic ratio of raw materials, a series of samples with a three-dimensional (3D) hollow porous ternary multicomponent heterostructure has been successfully synthesized via a facile template-free solvothermal approach and subsequently annealing and phosphating treatments, and its formation mechanism is also investigated. By virtue of compositional and structural advantages, the optimized NiCoP (NiCoP/CoP/CoP) nanoparticles show very high mass activity (436.

Pore structure dependent activity and durability of mesoporous rhodium nanoparticles towards the methanol oxidation reaction.

This work reports a significant effect of porous structures on the electrocatalytic methanol oxidation performances of Rh-based catalysts. It is demonstrated that a three-dimensional net-like mesoporous structure with ultrathin subunits is beneficial to exposing more active sites and boosting electron transfer inside particles, thus presenting the highest activity.

Encapsulating mesoporous metal nanoparticles: towards a highly active and stable nanoreactor for oxidative coupling reactions in water.

We design and prepare a highly active and stable nanoreactor via encapsulating various mesoporous metal nanoparticles with an amphiphilic hollow shell, which presents excellent performance in oxidative coupling reactions in water for efficient production of α,β-unsaturated ketones.

Janus N-Doped Carbon@Silica Hollow Spheres as Multifunctional Amphiphilic Nanoreactors for Base-Free Aerobic Oxidation of Alcohols in Water.

The hydrophobicity/hydrophilicity of nanocatalysts has a significant impact on their performances via modulating the adsorption, transfer, and desorption of reactants/products. In this work, we reported a novel multifunctional amphiphilic nanoreactor composed of Janus nitrogen-doped carbon@silica hollow nanostructure and ultrasmall Pt nanoparticles. The core/shell polybenzoxazine@mesosilica spheres were used as the precursor for pyrolysis.

Janus mesoporous silica nanosheets with perpendicular mesochannels: affording highly accessible reaction interfaces for enhanced biphasic catalysis.

A Janus mesosilica nanosheet with perpendicular mesochannels has been explored to use as a highly efficient interfacial catalyst for biphasic reactions. Owing to the excellent interfacial activity and the highly accessible reaction interface, a significantly enhanced catalytic activity is presented in aqueous hydrogenation reactions.

Flow Pickering Emulsion Interfaces Enhance Catalysis Efficiency and Selectivity for Cyclization of Citronellal.

Cyclization of citronellal is a necessary intermediate step to produce the important flavor chemical (-)-menthol. Here, a continuous-flow Pickering emulsion (FPE) strategy for selective cyclization of citronellal to (-)-isopulegol by using water droplets hosting a heteropolyacid (HPA) catalyst to fill a column reactor is demonstrated. Owing to the large liquid-liquid interface and the excellent confinement ability of droplets toward HPA, the FPE system exhibited a much higher catalysis efficiency than its batch counterpart (2-5-fold) and an excellent durability (two months).

Guidance from an in situ hot stage in TEM to synthesize magnetic metal nanoparticles from a MOF.

A series of in situ hot stage experiments using transmission electron microscopy (TEM) were studied to directly observe the transition of a Ni-MOF to Ni nanoparticles wrapped in carbon (Ni-NPC) over temperatures ranging from ambient temperature to 700 °C. Ni-NPC-600 displays high catalytic activity in 4-nitrophenol reduction and high conversion, even after 10 cycles.

Amphiphilic hollow porous shell encapsulated Au@Pd bimetal nanoparticles for aerobic oxidation of alcohols in water.

This work describes the design, synthesis and analysis of an amphiphilic hollow mesoporous shell encapsulating catalytically active Au@Pd bimetal nanoparticles. The particles exhibited excellent catalytic activity and stability in the aerobic oxidation of primary and secondary alcohols to their corresponding aldehydes or ketones in water when using air as an oxidizing agent under atmospheric pressure.

A one-step carbonization route towards nitrogen-doped porous carbon hollow spheres with ultrahigh nitrogen content for CO2 adsorption.

Nitrogen doped porous carbon hollow spheres (N-PCHSs) with an ultrahigh nitrogen content of 15.9 wt% and a high surface area of 775 m(2) g(-1) were prepared using Melamine-formaldehyde nanospheres as hard templates and nitrogen sources. The N-PCHSs were completely characterized and were found to exhibit considerable CO2 adsorption performance (4.