Hierarchical CeO2@N-C Ultrathin Nanosheets for Efficient Selective Oxidation of Benzylic Alcohols in Water.

A monodisperse CeO2@N-C ultrathin nanosheet self-assembled hierarchical structure (USHR) has been prepared by metal-organic framework template methods. The uniform coating of nitrogen-doped carbon (N-C) layers could play an important role in the adsorption and activation of benzylic alcohol. The unique 3D hierarchical structure self-assembled by ultrathin nanosheets provided enough active sites for the catalytic reaction. Therefore, the CeO2@N-C USHR can afford excellent catalytic performance for selective oxidation of benzylic alcohols in water.

Niobium Boride/Graphene Directing High-Performance Lithium-Sulfur Batteries Derived from Favorable Surface Passivation.

Efficient catalysts are needed to accelerate the conversion and suppress the shuttling of polysulfides (LiPSs) to promote the further development of lithium-sulfur (Li-S) batteries. Intermetallic niobium boride (NbB2) has indefinite potential due to superior catalytic activity. Nonetheless, the lack of a rational understanding of catalysis creates a challenge for the design of catalysts. Herein, a NbB2/reduced graphene oxide-modified PP separator (NbB2/rGO/PP) is rationally designed. Essential, an in-depth insight into the catalysis mechanism of NbB2 toward LiPSs is established based on experiments and multiperspective measurement characterization, ab initio molecular dynamics (AIMD), and density functional theory (DFT). It has been uncovered that the actual catalyst that interacts with LiPSs in NbB2 is the passivated surface with an oxide layer (O2-NbB2), which occurs through B-O-Li and Nb-O-Li bonds, rather than the clean NbB2 surface. And the decomposition barrier of Li2S is greatly reduced by a substantial margin, dropping from 3.390 to 0.93 and 0.85 eV on the Nb-O and B-O surfaces, respectively, with fast Li+ diffusivity. Consequently, the cell with NbB2/rGO/PP as a functional separator achieves a high discharge capacity of 873 mAh g-1 at 1C after 100 cycles. Moreover, the benefits of NbB2/rGO/PP can be effectively maintained even at a high sulfur loading of 7.06 mg cm-2 without significant reduction and with a low electrolyte/sulfur ratio of 8 µL mg-1s. This study enhances our understanding of the catalytic mechanism of Li-S systems and presents a promising approach for developing electrocatalysts that are resilient to poisoning.

Mo2C catalyst leads to highly efficient hydrogen transfer of alcohols and amines to synthesize N-alkylamines.

We found that molybdenum carbide (Mo2C) can be applied as a novel and efficient heterogeneous catalyst for hydrogen transfer of anilines and alcohols to synthesize N-alkylamines. The results of experiments and DFT calculations demonstrate that Mo2C surface can reduce the energy barrier of the key step of alcohol dehydrogenation and generate a hydrogen spillover effect, thereby exhibiting outstanding catalytic performance.

Transforming Dye Molecules into Electrochemical Allies: Direct Red 80 as a Dual-Functional Electrolyte Additive for Dendrite-Free Aqueous Zinc-Ion Batteries.

Despite the numerous advantages of abundant zinc resources, low redox potential, and affordability, aqueous zinc-ion batteries (AZIBs) currently face limitations due to dendritic growth and side reactions. This study explores the use of low-cost and efficient anionic dyes, specifically Direct Red 80 (DR80) as dual-functional electrolyte additives to enhance the electrochemical performance of AZIBs and facilitate the reuse of dye wastewater. Experimental and theory calculation results all demonstrate that the DR80 molecules readily adsorb onto the surface of the zinc anode, creating a stable and robust solid electrolyte interphase layer. This layer acts as a protective barrier, effectively mitigating H+ attacks and reducing both hydrogen evolution and corrosion reactions. Additionally, it covers any initial protrusions on the zinc anode, preventing the occurrence of the "tip-effect" phenomenon and limiting access of water to the zinc anode, thereby minimizing water decomposition. Moreover, the sulfonic acid groups of DR80 molecules displace some water molecules in [Zn(H2O)6]2+, disrupting the original solvent sheath and reducing water decomposition. Especially, using the DR80 additive, the Zn/Zn cell reaches an impressive cycle life of 1500 h at 2 mA cm-2@1 mAh cm-2. Given the low cost and widespread availability, this additive shows great potential in the future practical implementation of AZIBs.

Peroxidase-like Nanozymes for Point-of-Care SERS Sensing and Wound Healing.

The emergence of nanozymes provides a potential method for combating multidrug-resistant bacteria resulted from the abuse of antibiotics. However, in nanozyme-catalyzed systems, few studies have addressed the actual hydrogen peroxide (H2O2) level involved in sterilization. Herein, we designed a high-efficiency peroxidase-mimicking nanozyme with surface-enhanced Raman scattering (SERS) property by assembling gold nanoparticles on single-layer Cu2+-C3N4 (AuNP-Cu2+-C3N4). The nanozyme effectively converts the low-active Raman reporter 3,3',5,5'-tetramethylbenzidine (TMB) into its oxidized form with H2O2, resulting in SERS signal changes, thereby achieving highly sensitive quantification of H2O2 with limit of detection as low as 0.60 µM. More importantly, the nanozyme can specifically catalyze H2O2 into antibacterial hydroxyl radicals. In vitro and in vivo evaluations demonstrate the remarkable antibacterial efficacy of the nanozyme/H2O2 combination against Staphylococcus aureus (up to 99.9%), which could promote wound healing in mice and allow point-of-care monitoring the amount of H2O2 participated in effective sterilization. This study not only displays great potential in combining multiple functionalities of nanomaterials for versatile bioassays but also provides a promising approach to design nanozymes for biomedical and catalytic applications.

COx-free hydrogen production via ammonia decomposition over mesoporous Co/Al2O3 catalysts with highly dispersed Co species synthesized by a facile method.

Transition metals have been considered as potential catalysts for ammonia decomposition to produce COx-free hydrogen for fuel cells. However, the facile synthesis of transition metal catalysts with small size active species, high porosity and good structural stability is still a challenge in catalytic NH3 decomposition. Herein, mesoporous Co/Al2O3 catalysts with various cobalt contents were synthesized by a facile modified sol-gel method. The catalyst 15CoAl with 15 at% cobalt content realizes the optimal catalytic NH3 decomposition performance. 92% NH3 conversion at 600 °C is achieved with a gaseous hourly space velocity (GHSV) of 24 000 cm3 gcat-1 h-1 and a hydrogen formation rate of 33.9 mmol gcat-1 min-1 at 600 °C is maintained after a 120 h long-duration stability test. Uniform small cobalt particles with high dispersion are well embedded into the skeleton of the mesoporous Al2O3 matrix. The aggregation of active cobalt species during the high temperature reaction can be effectively prevented by the mesoporous Al2O3 matrix due to the strong interaction between them, thus ensuring a good catalytic performance for ammonia decomposition.

POSS and imidazolium-constructed ionic porous hypercrosslinked polymers with multiple active sites for synergistic catalytic CO2 transformation.

In this work, we reported a facile one-pot approach to construct polyhedral oligomeric silsesquioxane (POSS) and imidazolium-based ionic porous hypercrosslinked polymers (denoted as iPHCPs) with multiple active sites towards efficient catalytic conversion of carbon dioxide (CO2) to high value-added cyclic carbonates. The targeted iPHCPs were synthesized from a rigid molecular building block octavinylsilsesquioxane (VPOSS) and a newly-designed phenyl-based imidazolium ionic crosslinker through the AlCl3-catalyzed Friedel-Crafts reaction. The desired multiple active sites come from the mixed anions including free Cl- and Br- anions, and in situ formed Lewis acidic metal-halogen complex anions [AlCl3Br]- within imidazolium moieties and POSS-derived Si-OH groups during the synthetic process. The typical polymer iPHCP-12 possesses a hierarchical micro-/mesoporous structure with a high surface area up to 537 m2 g-1 and shows a fluffy nano-morphology. By virtue of the co-existence of free nucleophilic Cl- and Br- anions, the metal complex anion [AlCl3Br]- with both electrophilic and nucleophilic characters and electrophilic hydrogen bond donor (HBD) Si-OH groups, iPHCP-12 is regarded as an efficient recyclable heterogeneous catalyst for synergistic catalytic conversion of CO2 with various epoxides into cyclic carbonates under mild conditions. The present work provides a succinct one-pot strategy to construct task-specific ionic porous hypercrosslinked polymers from easily available modules for the targeted catalytic applications.

An easy way to identify high performing covalent organic frameworks for hydrogen storage.

The complexity of secondary building units (SBUs), an indicator that can not only be calculated but also visually estimated, is proposed as a highly indicative predictor of hydrogen storage performance. With optimal pore sizes and void fractions, selecting COFs consisting of simple SBUs greatly improves the probability of top-performing COFs towards the ultimate DOE hydrogen storage target, as an easy principle for experimentalists to select hydrogen adsorbents.

Metalated-bipyridine-based porous hybrid polymers with POSS-derived Si-OH groups for synergistic catalytic CO2 fixation.

Herein, we construct a new series of N-heterocyclic ligand bipyridine-based porous hybrid polymers (denoted Bpy-PHPs) from the Heck reaction of a rigid building unit octavinylsilsesquioxane (VPOSS) and 5,5'-dibromo-2,2'-bipyridine. Surprisingly, the typical sample Bpy-PHP-4 was found to be a metal-/halogen-free heterogeneous catalyst in the cycloaddition reaction of CO2 with a few epoxides under atmospheric pressure. After coordination with ZnBr2, the resultant ZnBr2@Bpy-PHP-4 afforded largely enhanced heterogeneous catalytic activities upon the conversion of carbon dioxide (CO2) and various epoxides into cyclic carbonates without using any co-catalysts under mild conditions. The moderate catalytic activities of Bpy-PHP-4 may be due to the presence of hydrogen bond donors (HBDs), i.e., polyhedral oligomeric silsesquioxane (POSS)-derived Si-OH groups and N active sites from Bpy linkers. In comparison, the high catalytic efficiency of ZnBr2@Bpy-PHP-4 should be attributed to the synergistic catalysis of Si-OH groups, N active atoms, and Bpy-coordinated ZnBr2. Moreover, the catalyst ZnBr2@Bpy-PHP-4 can be easily recovered and reused ten times without any significant loss of catalytic activities. This work affords an efficient metal-based porous hybrid polymer heterogeneous catalyst for the cycloaddition reaction of CO2 and epoxides under mild and co-catalyst-free conditions.

Facile synthesis of crystalline viologen-based porous ionic polymers with hydrogen-bonded water for efficient catalytic CO2 fixation under ambient conditions.

In this work, we report a series of crystalline viologen-based porous ionic polymers (denoted VIP-X, X = Cl or Br), that have in situ formed dicationic viologens paired with halogen anions and intrinsic hydrogen-bonded water molecules, towards metal-free heterogeneous catalytic conversion of carbon dioxide (CO2) under mild conditions. The targeted VIP-X materials were facilely constructed via the Menshutkin reaction of 4,4'-bipyridine with 4,4'-bis(bromomethyl)biphenyl (BCBMP) or 4,4'-bis(chloromethyl)biphenyl (BBMBP) monomers. Their crystalline and porous structures, morphological features and chemical structures and compositions were fully characterized by various advanced techniques. The optimal catalyst VIP-Br afforded a high yield of 99% in the synthesis of cyclic carbonate by CO2 cycloaddition with epichlorohydrin under atmospheric pressure (1 bar) and a low temperature (40 °C), while other various epoxides could be also converted into cyclic carbonates under mild conditions. Moreover, the catalyst VIP-Br could be separated easily and reused with good stability. The remarkable catalytic performance could be attributed to the synergistic effect of the enriched Br- anions and available hydrogen bond donors -OH groups coming from H-bonded water molecules.

Two-in-one: construction of hydroxyl and imidazolium-bifunctionalized ionic networks in one-pot toward synergistic catalytic CO2 fixation.

A succinct strategy was demonstrated for constructing a hydroxyl group and imidazolium-bifunctionalized ionic network via a one-pot quaternization. Key to success lies in the rational design of multi-imidazole precursor and hydroxyl-containing counterpart. Unique properties of the resultant ionic network render its high catalytic efficiency toward CO2 fixation under ambient conditions.

P-Doped carbons derived from cellulose as highly efficient metal-free catalysts for aerobic oxidation of benzyl alcohol in water under an air atmosphere.

P-Doped carbons, prepared by carbonizing phosphoric acid-treated cellulose, exhibit high catalytic activity in metal-free aerobic oxidation of benzyl alcohol to benzaldehyde (99.7% yield) in water under air. A high turnover frequency is obtained due to the doped P-species of C3PO, identified via experiments and DFT calculations.

Constructing POSS and viologen-linked porous cationic frameworks induced by the Zincke reaction for efficient CO2 capture and conversion.

POSS and viologen-linked porous cationic frameworks (V-PCIF-X, X = Cl, Br) are constructed via the Zincke reaction between octa(aminophenyl)silsesquioxane and viologen linkers. The typical V-PCIF-Br has a high surface area with abundant ionic sites, micro-/mesopores and Si-OH groups, serving as an efficient porous adsorbent and metal-free catalyst for simultaneous CO2 capture and conversion.

C3N4-H5PMo10V2O40: a dual-catalysis system for reductant-free aerobic oxidation of benzene to phenol.

Hydroxylation of benzene is a widely studied atom economical and environmental benign reaction for producing phenol, aiming to replace the existing three-step cumene process. Aerobic oxidation of benzene with O2 is an ideal and dream process, but benzene and O2 are so inert that current systems either require expensive noble metal catalysts or wasteful sacrificial reducing agents; otherwise, phenol yields are extremely low. Here we report a dual-catalysis non-noble metal system by simultaneously using graphitic carbon nitride (C(3)N(4)) and Keggin-type polyoxometalate H(5)PMo(10)V(2)O(40) (PMoV(2)) as catalysts, showing an exceptional activity for reductant-free aerobic oxidation of benzene to phenol. The dual-catalysis mechanism results in an unusual route to create phenol, in which benzene is activated on the melem unit of C(3)N(4) and O2 by the V-O-V structure of PMoV(2). This system is simple, highly efficient and thus may lead the one-step production of phenol from benzene to a more practical pathway.

Mesoporous polyoxometalate-based ionic hybrid as a triphasic catalyst for oxidation of benzyl alcohol with H(2)O(2) on water.

A self-assembled mesoporous polyoxometalate-based ionic hybrid catalyst [TMGHA]2.4H0.6PW was prepared by combination of alcohol amino-tethered guanidinium ionic liquid [TMGHA]Cl with Keggin phosphotungstic acid H3PW12O40 (PW). Nitrogen sorption experiment validated the formation of mesostructure with moderate BET surface area, and scanning and transmission electron microscopy (SEM and TEM) showed a fluffy coral-shaped morphology for the hybrid. The contact angle test displayed that the hybrid owned hydrophilic-hydrophobic balanced surface that exhibited well wettability for both water and organic substrate like benzyl alcohol. Therefore, the hybrid can efficiently catalyze the water-mediated triphasic oxidation of benzyl alcohol with H2O2. During the reaction, the triphase catalytic system showed a special "on water" effect mainly due to the suitable mesostructure and surface wettability, thus providing some clues for the preparation of green heterogeneous catalyst.