Facile Synthesis of Monodisperse Magnesium Oxide Microspheres via Seed‐Induced Precipitation and Their Applications in High‐ Performance Liquid Chromatography

Low‐cost, uniform, and monodisperse spherical particles are desirable for a variety of applications. We report the realization of uniform spherical magnesium oxide with a diameter of 10.5 μm and specific surface area of 140.9 m² g^–1 resulting from a facile seed‐induced precipitation in the presence of a trace amount of phosphate species. By optimizing the experimental parameters, the results demonstrate that the morphologies of magnesium oxide precursors are very sensitive to the amount and the sequence of addition of Mg₅(CO₃)₄(OH)₂ · 4H₂O seeds, as well as the amount and type of phosphate species. These particles have also been used as a packing material for high performance liquid chromatography. In comparison with the commercial spherical silica, as‐synthesized spherical magnesium oxide exhibits excellent efficiency in the separation of polycyclic aromatic hydrocarbons, and has a larger retention to planar compounds in contrast to non‐planar ones. It is believed that this method will provide a simple and versatile approach to large‐scale production of spherical magnesium oxide via a facile seed‐induced mechanism. The spherical magnesium oxide may find widespread use as a packing material in the group separation of polycylic aromatic hydrocarbons from target samples.     

Targeted Synergy between Adjacent Co Atoms on Graphene Oxide as an Efficient New Electrocatalyst for Li–CO2 Batteries

Li–CO₂ batteries are an attractive technology for converting CO₂ into energy. However, the decomposition of insulating Li₂CO₃ on the cathode during discharge is a barrier to practical application. Here, it is demonstrated that a high loading of single Co atoms (≈5.3%) anchored on graphene oxide (adjacent Co/GO) acts as an efficient and durable electrocatalyst for Li–CO₂ batteries. This targeted dispersion of atomic Co provides catalytically adjacent active sites to decompose Li₂CO₃. The adjacent Co/GO exhibits a highly significant sustained discharge capacity of 17 358 mA h g^?1 at 100 mA g^?1 for >100 cycles. Density functional theory simulations confirm that the adjacent Co electrocatalyst possesses the best performance toward the decomposition of Li₂CO₃ and maintains metallic‐like nature after the adsorption of Li₂CO₃.     

Topotactic Conversion Route to Mesoporous Quasi‐Single‐Crystalline Co3O4 Nanobelts with Optimizable Electrochemical Performance

The growth of mesoporous quasi‐single‐crystalline Co₃O₄ nanobelts by topotactic chemical transformation from α‐Co(OH)₂ nanobelts is realized. During the topotactic transformation process, the primary α‐Co(OH)₂ nanobelt frameworks can be preserved. The phases, crystal structures, morphologies, and growth behavior of both the precursory and resultant products are characterized by powder X‐ray diffraction (XRD), electron microscopy—scanning electron (SEM) and transmission electron (TEM) microscopy, and selected area electron diffraction (SAED). Detailed investigation of the formation mechanism of the porous Co₃O₄ nanobelts indicates topotactic nucleation and oriented growth of textured spinel Co₃O₄ nanowalls (nanoparticles) inside the nanobelts. Co₃O₄ nanocrystals prefer [0001] epitaxial growth direction of hexagonal α‐Co(OH)₂ nanobelts due to the structural matching of [0001] α‐Co(OH)₂//[111] Co₃O₄. The surface‐areas and pore sizes of the spinel Co₃O₄ products can be tuned through heat treatment of α‐Co(OH)₂ precursors at different temperatures. The galvanostatic cycling measurement of the Co₃O₄ products indicates that their charge–discharge performance can be optimized. In the voltage range of 0.0–3.0 V versus Li⁺/Li at 40 mA g^?1, reversible capacities of a sample consisting of mesoporous quasi‐single‐crystalline Co₃O₄ nanobelts can reach up to 1400 mA h g^?1, much larger than the theoretical capacity of bulk Co₃O₄ (892 mA h g^?1).     

A Zn–CO2 Flow Battery Generating Electricity and Methane

Metal–CO₂ batteries represent an economical and efficient CO₂ utilization technique, which provides a mechanism combining CO₂ reduction with electricity generation instead of electricity input. Existing metal–CO₂ batteries generally work in a closed system by recycling CO₂. In this study, a flow battery is designed with a hollow fiber of carbon nanotubes (cathode), Zn wire (anode), and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (electrolyte). The battery can continuously consume CO₂ to produce CH₄ under ambient conditions and promptly output the gaseous product through the hollow fiber, with a Faradaic efficiency up to 94%. Simultaneously, the battery generates electricity, with an energy density of 288.3 Wh kg^?1 (based on the zinc mass) and a stability up to 8 days. The high selectivity and efficiency of the battery is attributed to a water‐shuttling assisted proton mechanism and delicate electrode–electrolyte interplay. Moreover, the Zn anode is electrochemically renewed and the battery assembled with the regenerated Zn anode restores battery performances to the former level. The renewable characteristic implies that, if the regeneration of Zn anode is coupled to excessive renewable energy sources, then the Zn–CO₂ flow battery will be promising to accomplish a net reduction of CO₂ emission.     

Nitrogen‐Doped Cobalt Oxide Nanostructures Derived from Cobalt–Alanine Complexes for High‐Performance Oxygen Evolution Reactions

Taking advantage of the self‐assembling function of amino acids, cobalt–alanine complexes are synthesized by straightforward process of chemical precipitation. Through a controllable calcination of the cobalt–alanine complexes, N‐doped Co₃O₄ nanostructures (N‐Co₃O₄) and N‐doped CoO composites with amorphous carbon (N‐CoO/C) are obtained. These N‐doped cobalt oxide materials with novel porous nanostructures and minimal oxygen vacancies show a high and stable activity for the oxygen evolution reaction. Moreover, the influence of calcination temperature, electrolyte concentration, and electrode substrate to the reaction are compared and analyzed. The results of experiments and density functional theory calculations demonstrate that N‐doping promotes the catalytic activity through improving electronic conductivity, increasing OH^? adsorption strength, and accelerating reaction kinetics. Using a simple synthetic strategy, N‐Co₃O₄ reserves the structural advantages of micro/nanostructured complexes, showing exciting potential as a catalyst for the oxygen evolution reaction with good stability.     

Bimetal–Organic Framework: One‐Step Homogenous Formation and its Derived Mesoporous Ternary Metal Oxide Nanorod for High‐Capacity,High‐Rate,and Long‐Cycle‐Life Lithium Storage

Metal–organic frameworks (MOFs) and relative structures with uniform micro/mesoporous structures have shown important applications in various fields. This paper reports the synthesis of unprecedented mesoporous Ni_xCo_3?xO₄ nanorods with tuned composition from the Co/Ni bimetallic MOF precursor. The Co/Ni‐MOFs are prepared by a one‐step facile microwave‐assisted solvothermal method rather than surface metallic cation exchange on the preformed one‐metal MOF template, therefore displaying very uniform distribution of two species and high structural integrity. The obtained mesoporous Ni_0.3Co_2.7O₄ nanorod delivers a larger‐than‐theoretical reversible capacity of 1410 mAh g^?1 after 200 repetitive cycles at a small current of 100 mA g^?1 with an excellent high‐rate capability for lithium‐ion batteries. Large reversible capacities of 812 and 656 mAh g^?1 can also be retained after 500 cycles at large currents of 2 and 5 A g^?1, respectively. These outstanding electrochemical performances of the ternary metal oxide have been mainly attributed to its interconnected nanoparticle‐integrated mesoporous nanorod structure and the synergistic effect of two active metal oxide components.     

Mesoporous Co3O4 and CoO@C Topotactically Transformed from Chrysanthemum‐like Co(CO3)0.5(OH)·0.11H2O and Their Lithium‐Storage Properties

In this work, a novel hydrothermal route is developed to synthesize cobalt carbonate hydroxide, Co(CO₃)_0.5(OH)·0.11H₂O. In this method, sodium chloride salt is utilized to organize single‐crystalline nanowires into a chrysanthemum‐like hierarchical assembly. The morphological evolution process of this organized product is investigated by examining different reaction intermediates during the synthesis. The growth and thus the final assembly of the Co(CO₃)_0.5(OH)·0.11H₂O can be finely tuned by selecting preparative parameters, such as the molar ratio of the starting chemicals, the additives, the reaction time and the temperature. Using the flower‐like Co(CO₃)_0.5(OH)·0.11H₂O as a solid precursor, quasi‐single‐crystalline mesoporous Co₃O₄ nanowire arrays are prepared via thermal decomposition in air. Furthermore, carbon can be added onto the spinel oxide by a chemical‐vapor‐deposition method using acetylene, which leads to the generation of carbon‐sheathed CoO nanowire arrays (CoO@C). Through comparing and analyzing the crystal structures, the resultant products and their high crystallinity can be explained by a sequential topotactic transformation of the respective precursors. The electrochemical performances of the typical cobalt oxide products are also evaluated. It is demonstrated that tuning of the surface texture and the pore size of the Co₃O₄ products is very important in lithium‐ion‐battery applications. The carbon‐decorated CoO nanowire arrays exhibit an excellent cyclic performance with nearly 100% capacity retention in a testing range of 70 cycles. Therefore, this CoO@C nanocomposite can be considered to be an attractive candidate as an anode material for further investigation.     

Core–Shelled Low‐Oxidation State Oxides@Reduced Graphene Oxides Cubes via Pressurized Reduction for Highly Stable Lithium Ion Storage

Metal oxides have been regarded as promising next‐generation anode materials for rechargeable lithium ion batteries; however, their poor stability, which is caused by large volume changes during repeated lithiation/delithiation, remains a challenge. Here, conformally encapsulated low‐oxidation state oxide cubes with reduced graphene oxide (RGO) obtained via a new pressurized reduction consisting of external mechanical compression and internal thermokinetic reduction from highly porous metal oxides/RGO aerogel (RGOA) are reported. Using single crystalline (SC) cobalt oxides and iron oxide cubes as model systems, the SC‐Co₃O₄ or Fe₂O₃ cube/RGOA are pressurized into compacted xerogel along with a uniform thermokinetic reduction, which result in topotactic transformation to core‐shelled CoO/RGO or Fe₃O₄@RGO cubes. The SC‐CoO and SC‐Fe₃O₄ cubes isolated perfectly in the RGO shells have dramatically improved their cycling stabilities for lithium ion storage to hundreds of times.     

Ultrathin Cobalt–Manganese Nanosheets: An Efficient Platform for Enhanced Photoelectrochemical Water Oxidation with Electron‐Donating Effect

An ultrathin cobalt–manganese (Co‐Mn) nanosheet, consisting of amorphous Co(OH)_x layers and ultrasmall Mn₃O₄ nanocrystals, is designed as an efficient co‐catalyst on an α‐Fe₂O₃ film for photoelectrochemical (PEC) water oxidation. The uniformly distributed Co‐Mn nanosheets lead to a remarkable 2.6‐fold enhancement on the photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) and an impressive cathodic shift (≈200 mV) of onset potential compared with bare α‐Fe₂O₃ film. Furthermore, the decorated photoanode exhibits a prominent resistance against photocorrosion with excellent stability for over 10 h. Detailed mechanism investigation manifests that incorporation of Mn sites in the nanosheets could create electron donation to Co sites and facilitate the activation of the OH group, which drastically increases the catalytic activities for water oxidation. These findings provide valuable guidance for designing high‐performance co‐catalysts for PEC applications and open new avenues toward controlled fabrication of mixed metallic composites.     

Biphase Cobalt–Manganese Oxide with High Capacity and Rate Performance for Aqueous Sodium‐Ion Electrochemical Energy Storage

Manganese‐based metal oxide electrode materials are of great importance in electrochemical energy storage for their favorable redox behavior, low cost, and environmental friendliness. However, their storage capacity and cycle life in aqueous Na‐ion electrolytes is not satisfactory. Herein, the development of a biphase cobalt–manganese oxide (Co? Mn? O) nanostructured electrode material is reported, comprised of a layered MnO₂?H₂O birnessite phase and a (Co_0.83Mn_0.13Va_0.04)_tetra(Co_0.38Mn_1.62)_octaO_3.72 (Va: vacancy; tetra: tetrahedral sites; octa: octahedral sites) spinel phase, verified by neutron total scattering and pair distribution function analyses. The biphase Co? Mn? O material demonstrates an excellent storage capacity toward Na‐ions in an aqueous electrolyte (121 mA h g^?1 at a scan rate of 1 mV s^?1 in the half‐cell and 81 mA h g^?1 at a current density of 2 A g^?1 after 5000 cycles in full‐cells), as well as high rate performance (57 mA h g^?1 a rate of 360 C). Electrokinetic analysis and in situ X‐ray diffraction measurements further confirm that the synergistic interaction between the spinel and layered phases, as well as the vacancy of the tetrahedral sites of spinel phase, contribute to the improved capacity and rate performance of the Co? Mn? O material by facilitating both diffusion‐limited redox and capacitive charge storage processes.     

Finely Crafted 3D Electrodes for Dendrite‐Free and High‐Performance Flexible Fiber‐Shaped Zn–Co Batteries

Rechargeable aqueous Zn‐based batteries, benefiting from their good reliability, low cost, high energy/power densities, and ecofriendliness, show great potential in energy storage systems. However, the poor cycling performance due to the formation of Zn dendrites greatly hinders their practical applications. In this work, a trilayer 3D CC‐ZnO@C‐Zn anode is obtained by in situ growing ZIFs (zeolitic‐imidazolate frameworks) derived ZnO@C core–shell nanorods on carbon cloth followed by Zn deposition, which exhibits excellent antidendrite performance. Using CC‐ZnO@C‐Zn as the anode and a branch‐like Co(CO₃)_0.5(OH)_x·0.11H₂O@CoMoO₄ (CC‐CCH@CMO) as the cathode, a Zn–Co battery is rationally designed, displaying excellent energy/power densities (235 Wh kg^?1, 12.6 kW kg^?1) and remarkable cycling performance (71.1% after 5000 cycles). Impressively, when using a gel electrolyte, a highly customizable, fiber‐shaped flexible all‐solid‐state Zn–Co battery is assembled for the first time, which presents a high energy density of 4.6 mWh cm^?3, peak power density of 0.42 W cm^?3, and long durability (82% capacity retention after 1600 cycles) as well as excellent flexibility. The unique 3D electrode design in this study provides a novel approach to achieve high‐performance Zn‐based batteries, showing promising applications in flexible and portable energy‐storage systems.     

Nanocasting of Mesoporous In‐TM (TM = Co,Fe, Mn) Oxides: Towards 3D Diluted‐Oxide Magnetic Semiconductor Architectures

Transition metal (Co, Fe, Mn)‐doped In₂O_3?y mesoporous oxides are synthesized by nanocasting using mesoporous silica as hard templates. 3D ordered mesoporous replicas are obtained after silica removal in the case of the In‐Co and In‐Fe oxide powders. During the conversion of metal nitrates into the target mixed oxides, Co, Fe, and Mn ions enter the lattice of the In₂O₃ bixbyite phase via isovalent or heterovalent cation substitution, leading to a reduction in the cell parameter. In turn, non‐negligible amounts of oxygen vacancies are also present, as evidenced from Rietveld refinements of the X‐ray diffraction patterns. In addition to (In_1?xTM_x)₂O_3?y, minor amounts of Co₃O₄, α‐Fe₂O₃, and Mn_xO_y phases are also detected, which originate from the remaining TM cations not forming part of the bixbyite lattice. The resulting TM‐doped In₂O_3?y mesoporous materials show a ferromagnetic response at room temperature, superimposed on a paramagnetic background. Conversely, undoped In₂O_3?y exhibits a mixed diamagnetic‐ferromagnetic behavior with much smaller magnetization. The influence of the oxygen vacancies and the doping elements on the magnetic properties of these materials is discussed. Due to their 3D mesostructural geometrical arrangement and their room‐temperature ferromagnetic behavior, mesoporous oxide‐diluted magnetic semiconductors may become smart materials for the implementation of advanced components in spintronic nanodevices.     

Single‐Phase Mixed Transition Metal Carbonate Encapsulated by Graphene: Facile Synthesis and Improved Lithium Storage Properties

Transition metal carbonates (TMCs) with complex composition and robust hybrid structure hold great potential as high‐performance electrode materials for lithium‐ion batteries (LIBs). However, poor ionic/electronic conductivities and large volume changes of TMCs during lithiation/delithiation processes have hindered their applications. Herein, single‐phase Mn? Co mixed carbonate composites encapsulated by reduced graphene oxide (Mn_xCo_1?xCO₃/RGO), in which Mn and Co species are distributed randomly in one crystal structure, are successfully synthesized through a facial liquid‐state method. When evaluated as LIB anodes, the Mn_xCo_1?xCO₃/RGO composites exhibit enhanced electrochemical performance compared with the reference CoCO₃/RGO and MnCO₃/RGO. Specifically, the Mn_0.7Co_0.3CO₃/RGO delivers an ultrahigh capacity of 1454 mA h g^?1 after 130 cycles at 100 mA g^?1 and exhibits an ultralong cycling stability (901 mA h g^?1 after 1500 cycles at 2000 mA g^?1). This is the best lithium storage performance among carbonate‐based anodes reported up to date. Such superb performance is attributed to the hybrid structure and enhanced electroconductivity due to the integration of Co and Mn into one crystal structure, which is complemented by electrochemical impedance spectroscopy and density functional theory calculations. The facile synthesis, promising electrochemical results, and scientific understanding of the Mn_xCo_1?xCO₃/RGO provides a design principle and encourages more research on TMCs‐based electrodes.     

Templating Synthesis of SnO2 Nanotubes Loaded with Ag2O Nanoparticles and Their Enhanced Gas Sensing Properties

A new kind of SnO₂ nanotubes loaded with Ag₂O nanoparticles can be synthesized by using Ag@C coaxial nanocables as sacrificial templates. The composition of silver in SnO₂ nanotubes can be controlled by tuning the compositions of metallic Ag in Ag@C sacrificial templates, and the morphology of tubular structures can be changed by use of nanocables with different thicknesses of carbonaceous layer. This simple strategy is expected to be extended for the fabrication of similar metal‐oxide doped nanotubes using different nanocable templates. In contrast to SnO₂@Ag@C nanocables as well as to other types of SnO₂ reported previously, the Ag₂O‐doped SnO₂ nanotubes exhibit excellent gas sensing behaviors. The dynamic transients of the sensors demonstrated both their ultra‐fast response (1–2 s) and ultra‐fast recovery (2–4 s) towards ethanol, and response (1–4 s) and recovery (4–5 s) towards butanone. The combination of SnO₂ tubular structure and catalytic activity of Ag₂O dopants gives a very attractive sensing behavior for applications as real‐time monitoring gas sensors with ultra‐fast responding and recovering speed.     

Barium Hydroxide as an Interlayer Between Zinc Oxide and a Luminescent Conjugated Polymer for Light‐Emitting Diodes

A study of hybrid light‐emitting diodes (HyLEDs) fabricated with and without solution‐processible Cs₂CO₃ and Ba(OH)₂ inorganic interlayers is presented. The interlayers are deposited between a zinc oxide electron‐injection layer and a fluorescent emissive polymer poly(9‐dioctyl fluorine–alt‐benzothiadiazole) (F8BT) layer, with a thermally evaporated MoO₃/Au layer used as top anode contact. In comparison to Cs₂CO₃, the Ba(OH)₂ interlayer shows improved charge carrier balance in bipolar devices and reduced exciton quenching in photoluminance studies at the ZnO/Ba(OH)₂/F8BT interface compared to the Cs₂CO₃ interlayer. A luminance efficiency of ≈28 cd A^?1 (external quantum efficiency (EQE) ≈ 9%) is achieved for ≈1.2 μm thick single F8BT layer based HyLEDs. Enhanced out‐coupling with the aid of a hemispherical lens allows further efficiency improvement by a factor of 1.7, increasing the luminance efficiency to ≈47cd A^?1, corresponding to an EQE of 15%. The photovoltaic response of these structures is also studied to gain an insight into the effects of interfacial properties on the photoinduced charge generation and back‐recombination, which reveal that Ba(OH)₂ acts as better hole blocking layer than the Cs₂CO₃ interlayer.     

Template‐Directed Liquid ALD Growth of TiO2 Nanotube Arrays: Properties and Potential in Photovoltaic Devices

Dense and well‐aligned arrays of TiO₂ nanotubes extending from various substrates are successfully fabricated via a new liquid‐phase atomic layer deposition (LALD) in nanoporous anodic alumina (AAO) templates followed by alumina dissolution. The facile and versatile process circumvents the need for vacuum conditions critical in traditional gas‐phase ALD and yet confers ALD‐like deposition rates of 1.6–2.2 Å cycle^?1, rendering smooth conformal nanotube walls that surpass those achievable by sol–gel and Ti‐anodizing techniques. The nanotube dimensions can be tuned, with most robust structures being 150–400 nm tall, 60–70 nm in diameter with 5–20 nm thick walls. The viability of TiO₂ nanotube arrays deposited on indium tin oxide (ITO)–glass electrodes for application in model hybrid poly(3‐hexylthiophene) (P3HT):TiO₂ solar cells is studied. The results achieved provide platforms and research directions for further advancements.     

A Microbial‐Mineralization‐Inspired Approach for Synthesis of Manganese Oxide Nanostructures with Controlled Oxidation States and Morphologies

Manganese oxide nanostructures are synthesized by a route inspired by microbial mineralization in nature. The combination of organic molecules, which include antioxidizing and chelating agents, facilitates the parallel control of oxidation states and morphologies in an aqueous solution at room temperature. Divalent manganese hydroxide (Mn(OH)₂) is selectively obtained as a stable dried powder by using a combination of ascorbic acid as an antioxidizing agent and other organic molecules with the ability to chelate to manganese ions. The topotactic oxidation of the resultant Mn(OH)₂ leads to the selective formation of trivalent manganese oxyhydroxide (β‐MnOOH) and trivalent/tetravalent sodium manganese oxide (birnessite, Na_0.55Mn₂O₄·1.5H₂O). For microbial mineralization in nature, similar synthetic routes via intermediates have been proposed in earlier works. Therefore, these synthetic routes, which include in the present study the parallel control over oxidation states and morphologies of manganese oxides, can be regarded as new biomimetic routes for synthesis of transition metal oxide nanostructures. As a potential application, it is demonstrated that the resultant β‐MnOOH nanostructures perform as a cathode material for lithium ion batteries.     

Synthesis and Lithium Storage Properties of Co3O4 Nanosheet‐Assembled Multishelled Hollow Spheres

Single‐, double‐, and triple‐shelled hollow spheres assembled by Co₃O₄ nanosheets are successfully synthesized through a novel method. The possible formation mechanism of these novel structures was investigated using powder X‐ray diffraction, scanning and transmission electron microscopies, Fourier transform IR, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. Both poly(vinylpyrrolidone) (PVP) soft templates and the formation of cobalt glycolate play key roles in the formation of these novel multishelled hollow structures. When tested as the anode material in lithium‐ion batteries (LIBs), these multishelled microspheres exhibit excellent cycling performance, good rate capacity, and enhanced lithium storage capacity. This superior cyclic stability and capacity result from the synergetic effect of small diffusion lengths in the nanosheet building blocks and sufficient void space to buffer the volume expansion. This facile strategy may be extended to synthesize other transition metal oxide materials with hollow multishelled micro‐/nanostrucutures, which may find application in sensors and catalysts due to their unique structural features.     

Highly Connected Silicon–Copper Alloy Mixture Nanotubes as High‐Rate and Durable Anode Materials for Lithium‐Ion Batteries

Seeking high‐capacity, high‐rate, and durable anode materials for lithium‐ion batteries (LIBs) has been a crucial aspect to promote the use of electric vehicles and other portable electronics. Here, a novel alloy‐forming approach to convert amorphous Si (a‐Si)‐coated copper oxide (CuO) core–shell nanowires (NWs) into hollow and highly interconnected Si–Cu alloy (mixture) nanotubes is reported. Upon a simple H₂ annealing, the CuO cores are reduced and diffused out to alloy with the a‐Si shell, producing highly interconnected hollow Si–Cu alloy nanotubes, which can serve as high‐capacity and self‐conductive anode structures with robust mechanical support. A high specific capacity of 1010 mAh g^?1 (or 780 mAh g^?1) has been achieved after 1000 cycles at 3.4 A g^?1 (or 20 A g^?1), with a capacity retention rate of ≈84% (≈88%), without the use of any binder or conductive agent. Remarkably, they can survive an extremely fast charging rate at 70 A g^?1 for 35 runs (corresponding to one full cycle in 30 s) and recover 88% capacity. This novel alloy‐nanotube structure could represent an ideal candidate to fulfill the true potential of Si‐loaded LIB applications.     

Vesicle‐Assisted Assembly of Mesoporous Ce‐Doped Pd Nanospheres with a Hollow Chamber and Enhanced Catalytic Efficiency

Mesoporous Ce‐doped Pd nanospheres with a hollow chamber are synthesized by chemical reduction of PdCl₂ with KBH₄ in an aqueous solution containing Ce(NO₃)₃ and Bu₄PBr. The later acts as a template for the hollow chamber via forming organic vesicles. During the liquid‐phase phenol hydrogenation to cyclohexanone, the as‐prepared catalyst exhibits a much‐higher activity than the corresponding solid nanoparticle catalyst prepared in the absence of Bu₄PBr. Meanwhile, the Ce dopants greatly enhance the activity and selectivity to cyclohexanone. The hollow chamber is quite stable against heating in solution and the catalyst could be used repetitively many times. Such a catalyst shows a good potential in industrial applications.