Hierarchically dual‐mesoporous TiO2 microspheres have been synthesized by a solvothermal process in the presence of 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMImBF4) and diethylenetriamine ...(DETA) as co‐templates. Secondary mesostructured defects in the hierarchical TiO2 microspheres produce oxygen vacancies, which not only significantly enhance photocatalytic activity in the degradation of methylene blue (1.7 times that with P25) and acetone (2.9 times that with P25), but are also beneficial for lithium storage. Moreover, we propose a mechanism to rationalize the role of this dual mesoporosity of the TiO2 microspheres in enhancing molecular diffusion, ion transportation, and electronic transitions.
Beneficial dual mesoporosity: Hierarchically dual‐mesoporous TiO2 has been synthesized by a co‐templating method. Its mesostructured defects caused by an ionic liquid lead to a high level of oxygen vacancies (see graphic), which significantly enhance its photoelectrochemical performance.
Confinement of noble nanometals in a zeolite matrix is a promising way to special types of catalysts that show significant advantages in size control, site adjustment, and nano‐architecture design. ...The beauty of zeolite‐confined noble metals lies in their unique confinement effects on a molecular scale, and thus enables spatially confined catalysis akin to enzyme catalysis. In this Minireview, the confined synthesis strategies of zeolite‐confined noble metals will be briefly discussed, showing the processes, advantages, features, and mechanisms. The confined catalysis carried on zeolite‐confined noble metals will be summarized, and great emphasis will be paid to the confinement effects involving size, encapsulation, recognition, and synergy. Great progress of atomic sites in the size effect, supercage stabilization in the encapsulation effect, site adsorption in the recognition effect, and cascade reaction in the synergy effect are highlighted. This Minireview is concluded with challenges and opportunities in terms of the synthesis of zeolite‐confined noble metals and their applications to design multifunctional catalysts with high catalytic activity, selectivity, and stability.
The beauty of zeolite‐confined noble metals lies in their unique confinement effects on a molecular scale, and thus enables spatially confined catalysis akin to enzyme catalysis. This Minireview summarizes synthesis strategies and targeted catalysis applications for multifunctional zeolite‐confined noble metal catalysts.
A solvothermal method to prepare PtNi alloys that have differing morphologies is described. By adjusting the feed ratio of Pt and Ni precursors in this process, PtNi alloys with different ...compositions (Pt : Ni atomic ratio from 1 : 3 to 3 : 1) and morphologies (evolution from nanobranches to nanoparticles) are generated. The prepared Pt48Ni52 alloy, which has a composite morphology comprised of nanobranches and nanoparticles, exhibits superior activity and durability towards the hydrogen evolution reaction (HER) in seawater compared to those of commercial Pt/C catalyst and other PtNi alloys that have different compositions and morphologies. The excellent seawater HER performance of Pt48Ni52 is ascribed to its nanobranch/nanoparticle morphology that optimally facilitates electron accumulation on Pt, which enhances resistance to chloride corrosion in seawater.
Corrosion control: A PtNi alloy with a composite morphology comprised of nanobranches and nanoparticles is described. The unique morphology of the PtNi alloy facilitates electron accumulation on Pt, which enhances its resistance to chloride corrosion and performance in electrocatalytic hydrogen production in seawater.
Detection of nanoscale objects is highly desirable in various fields such as early‐stage disease diagnosis, environmental monitoring and homeland security. Optical microcavity sensors are renowned ...for ultrahigh sensitivities due to strongly enhanced light‐matter interaction. This review focuses on single nanoparticle detection using optical whispering gallery microcavities and photonic crystal microcavities, both of which have been developing rapidly over the past few years. The reactive and dissipative sensing methods, characterized by light‐analyte interactions, are explained explicitly. The sensitivity and the detection limit are essentially determined by the cavity properties, and are limited by the various noise sources in the measurements. On the one hand, recent advances include significant sensitivity enhancement using techniques to construct novel microcavity structures with reduced mode volumes, to localize the mode field, or to introduce optical gain. On the other hand, researchers attempt to lower the detection limit by improving the spectral resolution, which can be implemented by suppressing the experimental noises. We also review the methods of achieving a better temporal resolution by employing mode locking techniques or cavity ring up spectroscopy. In conclusion, outlooks on the possible ways to implement microcavity‐based sensing devices and potential applications are provided.
Single nanoparticle detection is of critical importance in various fields from fundamental research to practical applications. Optical microcavities are excellent candidates to be employed in ultra‐sensitive sensing due to significantly enhanced light‐matter interaction. The sensing performance can be improved by obtaining better spectral resolution and temporal resolution, and techniques can be applied to realize practical and portable sensors using microcavities.
An electrocatalyst composed of RuO2 surrounded by interfacial carbon, is synthesized through controllable oxidization‐calcination. This electrocatalyst provides efficient charge transfer, numerous ...active sites, and promising activity for pH‐universal electrocatalytic overall seawater splitting. An electrolyzer with this catalyst gives current densities of 10 mA cm−2 at a record low cell voltage of 1.52 V, and shows excellent durability at current densities of 10 mA cm−2 for up to 100 h. Based on the results, a mechanism for the catalytic activity of the composite is proposed. Finally, a solar‐driven system is assembled and used for overall seawater splitting, showing 95% Faraday efficiency.
An electrocatalyst composed of RuO2 surrounded by interfacial carbon is synthesized through controllable oxidization‐calcination. The interfacial carbon in RuO2/carbon compositions can provide efficient charge transfer and enhanced structural stability for the RuO2, which exhibits promising activity for pH‐universal electrocatalytic overall seawater splitting and its application in the solar‐driven electrolyzer.
A room‐temperature, visible‐light‐driven N‐centered iminyl radical‐mediated and redox‐neutral C−C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has ...been accomplished. The strategy tolerates a wide range of O‐acyl oximes and unsaturated systems, such as alkenes, silyl enol ethers, alkynes, and isonitrile, enabling highly selective formation of various chemical bonds. This method thus provides an efficient approach to various diversely substituted cyano‐containing alkenes, ketones, carbocycles, and heterocycles.
A visible‐light‐driven room‐temperature N‐centered iminyl radical‐mediated and redox‐neutral C−C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has been accomplished. The strategy tolerates a wide range of O‐acyl oximes and alkenes, silyl enol ethers, alkynes, and isonitrile. This method allows access to various cyano‐containing alkenes, ketones, carbocycles, and heterocycles.
The evolution of cost‐effective and reserve‐rich nonprecious metals (NPMs) to replace precious metal electrocatalysts is of significant interest in modern electrocatalysis. The confinement effects in ...NPM‐based nanoparticles encapsulated in carbon nanoshells have been considered as an emerging and efficient way to special types of electrocatalysts which facilitate electrocatalytic activity and stability, even under rigorous conditions. This review focuses on the unique individual carbon encapsulation for high‐performance design of NPM‐based electrocatalysts, outlining all confinement synthesis methods, mechanistic studies on confinement effects, and the emerging practical reactions. It begins first introducing the synthetic methods for NPM‐based core@carbon shell electrocatalysts, and then follows clarification of the relationship between the fundamental confinement effects and the performance improvement of carbon shell encapsulating NPM‐based electrocatalysts. Further and detailed discussions on the alloying effect, doping effect, and heterojunction effect of the NPM‐based core to alter the electronic situation which affects the electrocatalytic performance are subsequently provided. Finally, the review provides a perspective on challenges and opportunities in future research with respect to both in‐depth theoretical research and potential design concept of such NPM‐based core@carbon shell electrocatalysts.
Individual nonprecious metal (NPM)‐based core@carbon shell electrocatalysts have attracted extensive attention as one of the promising electrocatalytic materials. Confined within the carbon shell endows the integral electrocatalysts with good physical and chemical properties. Further alloying, doping, and heterojunction design of the cores provide abundant options for diverse electrocatalytic reactions. The structure–performance relationship is comprehensively reviewed via the experimental results and theoretical calculations.
The homojunction of oxygen/metal vacancies and its interfacial n–p effect on the physiochemical properties are rarely reported. Interfacial n–p homojunctions of TiO2 are fabricated by directly ...decorating interfacial p‐type titanium‐defected TiO2 around n‐type oxygen‐defected TiO2 nanocrystals in amorphous–anatase homogeneous nanostructures. Experimental measurements and theoretical calculations on the cell lattice parameters show that the homojunction of oxygen and titanium vacancies changes the charge density of TiO2; a strong EPR signal caused by oxygen vacancies and an unreported strong titanium vacancies signal of 2D 1H TQ‐SQ MAS NMR are present. Amorphous–anatase TiO2 shows significant performance regarding the photogeneration current, photocatalysis, and energy storage, owing to interfacial n‐type to p‐type conductivity with high charge mobility and less structural confinement of amorphous clusters. A new “homojunction of oxygen and titanium vacancies” concept, characteristics, and mechanism are proposed at an atomic‐/nanoscale to clarify the generation of oxygen vacancies and titanium vacancies as well as the interface electron transfer.
The homojunction of oxygen and titanium vacancies developed in the amorphous–anatase interface of nanostructured TiO2 results in a unique n–p electronic transmission, which is mostly preferred to the mobility of electronic charge carriers. It also contributes to significant performance regarding photogeneration current, photocatalysis, and energy storage.
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