Search

The atom-cluster interaction has recently been exploited as an effective way to increase the performance of metal-nitrogen-carbon catalysts for oxygen reduction reaction (ORR). However, the rational design of such catalysts and understanding their structure-property correlations remain a great challenge. Herein, we demonstrate that the introduction of adjacent metal (M)-N 4 single atoms (SAs) could significantly improve the ORR performance of a well-screened Fe atomic cluster (AC) catalyst by combining density functional theory (DFT) calculations and experimental analysis. The DFT studies suggest that the Cu-N 4 SAs act as a modulator to assist the O 2 adsorption and cleavage of O-O bond on the Fe AC active center, as well as optimize the release of OH* intermediates to accelerate the whole ORR kinetic. The depositing of Fe AC with Cu-N 4 SAs on nitrogen doped mesoporous carbon nanosheet are then constructed through a universal interfacial monomicelles assembly strategy. Consistent with theoretical predictions, the resultant catalyst exhibits an outstanding ORR performance with a half-wave potential of 0.92 eV in alkali and 0.80 eV in acid, as well as a high power density of 214.8 mW cm -2 in zinc air battery. This work provides a novel strategy for precisely tuning the atomically dispersed poly-metallic centers for electrocatalysis., (© 2023 Wiley-VCH GmbH.)

The development of highly efficient and stable oxygen reduction electrocatalysts and revealing their underlying catalytic mechanism are crucial in expanding the applications of metal-air batteries. Herein, an excellent FeCo alloy nanoparticles (NPs)-decorated N-doped mesoporous carbon electrocatalyst (FeCo/NC) for oxygen reduction reaction, prepared through the pyrolysis of a dual metal containing metal-organic framework composite scaffold is reported. Benefiting from the highly exposed bimetal active sites and the carefully designed structure, the Fe 0.25 Co 0.75 /NC-800 catalyst exhibits a promising electrocatalytic activity and a superior durability, better than those of the state-of-the-art catalysts. Suggested by both the X-ray absorption fine structures and the density functional theoretical calculation, the outstanding catalytic performance is originated from the synergistic effects of the bimetallic loading in NC catalysts, where the electronic modulation of the Co active sites from the nearby Fe species leads to an optimized binding strength for reaction intermediates. This work demonstrates a class of highly active nonprecious metals electrocatalysts and provides valuable insights into investigating the structure-performance relationship of transition metal-based alloy catalysts., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Recent efforts have observed nanoscaled chemical short-range order in bulk high-entropy alloys (HEAs). Simultaneously inspired with the nanostructuring technology, HEA nanoparticles (NPs) with complete chemical order may be achieved. Herein, structurally ordered HEA (OHEA) NPs are constructed on a novel 2D nitrogen-rich mesoporous carbon sandwich framework (OHEA-mNC) by combining a ligand-assisted interfacial assembly with NH 3 annealing. Characterization results show that the resultant materials possess an ultrathin 2D nanosheet structure with large mesopores (≈10 nm), where structurally ordered HEA NPs with an L1 2 phase are homogeneously dispersed. The atom-resolved chemical analyses explicitly determine the location of each atomic site. When being evaluated for the oxygen reduction reaction, the OHEA-mNC NPs afford a greatly enhanced catalytic performance, including a large half-wave potential (0.90 eV) and a high durability (0.01 V decay after 10 000 cycles) compared with the disordered HEA and commercial Pt/C catalysts. The excellent performance is attributed to the enhanced mass transfer rate, improved electron conductivity, and the presence of the stable chemically ordered HEA phase, as revealed by both the experimental results and theoretical calculation. This study suggests a highly feasible process to achieve structurally ordered HEA NPs with advanced mesoporous function in the electrochemical field., (© 2022 Wiley-VCH GmbH.)

Here, we report a universal single-atom coating (SAC) strategy by taking advantage of the rich chemistry of tannic acid (TA). TA units not only self-assemble into a cross-linked porous polyphenolic framework, but also can grip on different substates via multiple binding modes. Benefiting from the diverse chelating ability of TA, a series of mono-, and bi-metallic SACs can be formed on substrates of different materials (e. g., carbon, SiO 2 , TiO 2 , MoS 2 ), dimensions (0D-3D) and sizes (50 nm-5 cm). By contrast, uniform SAC cannot be achieved using common approaches such as pyrolysis of metal-dopamine complexes or metal-organic frameworks. As a proof-of-concept demonstration, two Co SACs immobilized on graphene and TiO 2 were prepared. The former one shows six-fold higher mass activity than Pt/C toward oxygen reduction. The latter one displays outstanding photocatalytic activity owing to the high activity of the single atoms and the formation of the single-atom coating-TiO 2 heterojunction., (© 2022 Wiley-VCH GmbH.)

The 2D titanium carbide MXene with both extraordinary electromagnetic attenuation and elastic properties has shown great potential as the building block for constructing mechanically robust microwave absorbing composites (MACs). However, the weak thermal stability has inhibited the successful incorporation of MXene into the inorganic MACs matrix so far. Herein, an ultralow temperature sintering strategy to fabricate a hierarchical aluminosilicate glass composite is demonstrated by using EMT zeolite as starting powder, which can not only endow the composites with high sinterability, but also facilitate the alignment of MXene in the glass matrix. Accordingly, the highly oriented MXene and mesoporous structure can effectively reduce the conduction loss in the out-of-plane direction while maintaining its large polarization loss. Meanwhile, the in situ formed Ni nanoparticles via ion exchange serve as a synergistic modulator to further improve the attenuation capability and impedance matching of composite, resulting in a low reflection loss of -59.5 dB in X band and general values below -20 dB with a low fitting thickness from 4 to 18 GHz. More attractively, such a delicate structure also gives the composite a remarkable fracture strength and contact-damage-resistance, which qualifies the mesoporous glass composite as a structural MACs with a superior comprehensive performance., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Mesoporous materials have drawn more and more attention in the field of biosensors due to their high surface areas, large pore volumes, tunable pore sizes, as well as abundant frameworks. In this review, the progress on mesoporous materials-based biosensors from enzymatic to nonenzymatic are highlighted. First, recent advances on the application of mesoporous materials as supports to stabilize enzymes in enzymatic biosensing technology are summarized. Special emphasis is placed on the effect of pore size, pore structure, and surface functional groups of the support on the immobilization efficiency of enzymes and the biosensing performance. Then, the development of a nonenzymatic strategy that uses the intrinsic property of mesoporous materials (carbon, silica, metals, and composites) to mimic the behavior of enzymes for electrochemical sensing of some biomolecules is discussed. Finally, the challenges and perspective on the future development of biosensors based on mesoporous materials are proposed., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Despite the ultrahigh intrinsic strength of multiwalled carbon nanotube (MWCNT), the strengthening effect on ceramic matrix composite remains far from expectation mainly due to the weak load transfer between the reinforcement and ceramic matrix. With the assistance of the in situ pullout test, it is revealed that the liquid-phase sintering (LPS) can serve as a novel strategy to achieve effective load transfer in MWCNT reinforced ceramic matrix composites. The YAlO 3 formed liquid phase during spark plasma sintering of SiC composite greatly facilitates radical elastic deformation of MWCNT, leading to highly increased interfacial shear strength (IFSS) as well as interlayer shear resistance (ISR) of nested walls. The liquid phase with superior wettability can even penetrate into the defects of MWCNT, which further increases the ISR of MWCNT. Moreover, the first-principles calculation indicates that the oxygen terminated YAlO 3 phase displays much stronger bonding compared with SiC matrix, which is also responsible for the large IFSS in the composite. As a result, as high as 30% improvement of bending strength is achieved in the composite with only 3 wt% MWCNT in comparison to the monolithic ceramic, manifesting the unprecedented strengthening effect of MWCNT assisted by LPS., Competing Interests: The authors declare no conflict of interest., (© 2020 The Authors. Published by Wiley‐VCH GmbH.)

The direct assembly of functional nanoparticles into a highly crystalline mesoporous semiconductor with oriented configurations is challenging but of significance. Herein, an evaporation induced oriented co-assembly strategy is reported to incorporate SnO 2 nanocrystals (NCs) into a 3D branched mesoporous TiO 2 framework by using poly(ethylene oxide)-block-polystyrene (PEO- b -PS) as the template, SnO 2 NCs as the direct tin source, and titanium butoxide (TBOT) as the titania precursor. Owing to the combined properties of ultrasmall particle size (3-5 nm), excellent dispersibility and presence of abundant hydroxyl groups, SnO 2 NCs can easily interact with PEO block of the template through hydrogen bonding and co-assemble with hydrolyzed TBOT to form a novel hierarchical branched mesoporous structure (SHMT). After calcination, the obtained composites exhibit a unique 3D flower-like structure, which consists of numerous mesoporous rutile TiO 2 branches with uniform cylindrical mesopores (≈9 nm). More importantly, the SnO 2 NCs are homogeneously distributed in the mesoporous TiO 2 matrix, forming numerous n-n heterojunctions. Due to the unique textual structures, the SHMT-based gas sensors show excellent gas sensing performance with fast response/recovery dynamics, high sensitivity, and selectivity toward ethanol., Competing Interests: The authors declare no conflict of interest., (© 2019 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.)