Boosted Oxygen Kinetics of Hierarchically Mesoporous Mo2C/C for High-current-density Zn-air Battery.

The high-current-density Zn-air battery shows big prospects in next-generation energy technologies, while sluggish O2 reaction and diffusion kinetics barricade the applications. Herein, the sequential assembly is innovatively demonstrated for hierarchically mesoporous molybdenum carbides/carbon microspheres with a tunable thickness of mesoporous carbon layers (Meso-Mo2C/C-x, where x represents the thickness). The optimum Meso-Mo2C/C-14 composites (≈2 µm in diameter) are composed of mesoporous nanosheets (≈38 nm in thickness), which possess bilateral mesoporous carbon layers (≈14 nm in thickness), inner Mo2C/C layers (≈8 nm in thickness) with orthorhombic Mo2C nanoparticles (≈2 nm in diameter), a high surface area of ≈426 m2 g-1, and open mesopores (≈6.9 nm in size). Experiments and calculations corroborate the hierarchically mesoporous Mo2C/C can enhance hydrophilicity for supplying sufficient O2, accelerate oxygen reduction kinetics by highly-active Mo2C and N-doped carbon sites, and facilitate O2 diffusion kinetics over hierarchically mesopores. Therefore, Meso-Mo2C/C-14 outputs a high half-wave potential (0.88 V vs RHE) with a low Tafel slope (51 mV dec-1) for oxygen reduction. More significantly, the Zn-air battery delivers an ultrahigh power density (272 mW cm-2), and an unprecedented 100 h stability at a high-current-density condition (100 mA cm-2), which is one of the best performances.

Construction of sub micro-nano-structured silicon based anode for lithium-ion batteries.

The significant volume change experienced by silicon (Si) anodes during lithiation/delithiation cycles often triggers mechanical-electrochemical failures, undermining their utility in high-energy-density lithium-ion batteries (LIBs). Herein, we propose a sub micro-nano-structured Si based material to address the persistent challenge of mechanic-electrochemical coupling issue during cycling. The mesoporous Si-based composite submicrospheres (M-Si/SiO2/CS) with a high Si/SiO2content of 84.6 wt.% is prepared by magnesiothermic reduction of mesoporous SiO2submicrospheres followed by carbon coating process. M-Si/SiO2/CS anode can maintain a high specific capacity of 740 mAh g-1at 0.5 A g-1after 100 cycles with a lower electrode thickness swelling rate of 63%, and exhibits a good long-term cycling stability of 570 mAh g-1at 1 A g-1after 250 cycles. This remarkable Li-storage performance can be attributed to the synergistic effects of the hierarchical structure and SiO2frameworks. The spherical structure mitigates stress/strain caused by the lithiation/delithiation, while the internal mesopores provide buffer space for Si expansion and obviously shorten the diffusion path for electrolyte/ions. Additionally, the amorphous SiO2matrix not only servers as support for structure stability, but also facilitates the rapid formation of a stable solid electrolyte interphase layer. This unique architecture offers a potential model for designing high-performance Si-based anode for LIBs.

Constructing mesoporous biochar derived from waste carton: Improving multi-site adsorption of dye wastewater and investigating mechanism.

The development of cost-efficient biochar adsorbent with a simple preparation method is essential to constructing efficient wastewater treatment system. Here, a low-cost waste carton biochar (WCB) prepared by a simple two-step carbonization was applied in efficiently removing Rhodamine B (RhB) in aqueous environment. The maximum ability of WCB for RhB adsorption was 222 mg/g, 6 and 10 times higher than both of rice straw biochar (RSB) and broadbean shell biochar (BSB), respectively. It was mainly ascribed to the mesopore structure (3.0-20.4 nm) of WCB possessing more spatial sites compared to RSB (2.2 nm) and BSB (2.4 nm) for RhB (1.4 nm✕1.1 nm✕0.6 nm) adsorption. Furthermore, external mass transfer (EMT) controlled mass transfer resistance (MTR) of the RhB sorption process by WCB which was fitted with the Langmuir model well. Meanwhile, the adsorption process was dominated by physisorption through van der Waals forces and π-π interactions. A mixture of three dyes in river water was well removed by using WCB. This work provides a straightforward method of preparing mesoporous biochar derived from waste carton with high-adsorption capacity for dye wastewater treatment.

Fe-Co Co-Doped 1D@2D Carbon-Based Composite as an Efficient Catalyst for Zn-Air Batteries.

A Fe-Co dual-metal co-doped N containing the carbon composite (FeCo-HNC) was prepared by adjusting the ratio of iron to cobalt as well as the pyrolysis temperature with the assistance of functionalized silica template. Fe1Co-HNC, which was formed with 1D carbon nanotubes and 2D carbon nanosheets including a rich mesoporous structure, exhibited outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activities. The ORR half-wave potential is 0.86 V (vs. reversible hydrogen electrode, RHE), and the OER overpotential is 0.76 V at 10 mA cm-2 with the Fe1Co-HNC catalyst. It also displayed superior performance in zinc-air batteries. This method provides a promising strategy for the fabrication of efficient transition metal-based carbon catalysts.

Controllable preparation of mesoporous spike gold nanocrystals for surface-enhanced Raman spectroscopy detection of micro/nanoplastics in water.

Microplastics and nanoplastics are emerging classes of environmental contaminants that pose significant threats to human health. In particular, small nanoplastics (<1 µm) have drawn considerable attention owing to their adverse effects on human health; for example, nanoplastics have been found in the placenta and blood. However, reliable detection techniques are lacking. In this study, we developed a fast detection method that combines membrane filtration technology and surface-enhanced Raman spectroscopy (SERS), which can simultaneously enrich and detect nanoplastics with sizes as small as 20 nm. First, we synthesized spiked gold nanocrystals (Au NCs), achieving a controlled preparation of thorns ranging from 25 nm to 200 nm and regulating the number of thorns. Subsequently, mesoporous spiked Au NCs were homogeneously deposited on a glass fiber filter membrane to form an Au film as a SERS sensor. The Au-film SERS sensor achieved in-situ enrichment and sensitive SERS detection of micro/nanoplastics in water. Additionally, it eliminated sample transfer and prevented the loss of small nanoplastics. Using the Au-film SERS sensor, we detected 20 nm to 10 µm standard polystyrene (PS) microspheres with a detection limit of 0.1 mg/L. We also realized the detection of 100 nm PS nanoplastics at the 0.1 mg/L level in tap water and rainwater. This sensor provides a potential tool for rapid and susceptible on-site detection of micro/nanoplastics, especially small-sized nanoplastics.

Bifunctional vanadium doped mesoporous Co3O4 on nickel foam towards highly efficient overall urea and water splitting in the alkaline electrolyte.

Developing more active and stable electrode materials for oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is necessary for electrocatalytic water and urea oxidation which can be used to generate hydrogen. Here, a low-cost vanadium-doped mesoporous cobalt oxide on Ni foam (V/meso-Co/NF) electrodes are obtained via the grouping of an in-situ citric acid (CA)-assisted evaporation-induced self-assembly (EISA) method and electrophoretic deposition process, and work as highly efficient and long-lasting electrocatalytic materials for OER/UOR. In particular, V/meso-Co/NF electrodes require 329 mV overpotential to maintain a 50 mA/cm2, with exceptional long-term durability of 30 h. Interestingly, V/meso-Co/NF also exhibits excellent electrocatalytic UOR performance, reaching 50 and 100 mA/cm2 versus RHE at low potentials of 1.34 and 1.35 V, respectively. By employing the V/meso-Co/NF materials as both the anode and cathode, this urea electrolysis assembly V/meso-Co/NF-5 (+,-) reaches current densities of 100 mA cm-2 at 1.62 V in KOH/urea, which is nearly 340 mV lesser than classical water electrolysis. The V/meso-Co/NF-5 electrocatalysts also exhibit remarkable durability for electrocatalytic OERs and UORs. The obtained findings revealed that the synthesized V/meso-Co/NF might be a promising electrode materials for overall urea-rich wastewater management and H2 generation from wastewater.

Mesoporous Carbon-Based Materials for Enhancing the Performance of Lithium-Sulfur Batteries.

The most promising energy storage devices are lithium-sulfur batteries (LSBs), which offer a high theoretical energy density that is five times greater than that of lithium-ion batteries. However, there are still significant barriers to the commercialization of LSBs, and mesoporous carbon-based materials (MCBMs) have attracted much attention in solving LSBs' problems, due to their large specific surface area (SSA), high electrical conductivity, and other unique advantages. The synthesis of MCBMs and their applications in the anodes, cathodes, separators, and "two-in-one" hosts of LSBs are reviewed in this study. Most interestingly, we establish a systematic correlation between the structural characteristics of MCBMs and their electrochemical properties, offering recommendations for improving performance by altering the characteristics. Finally, the challenges and opportunities of LSBs under current policies are also clarified. This review provides ideas for the design of cathodes, anodes, and separators for LSBs, which could have a positive impact on the performance enhancement and commercialization of LSBs. The commercialization of high energy density secondary batteries is of great importance for the achievement of carbon neutrality and to meet the world's expanding energy demand.

Preparation of Biochar with Developed Mesoporous Structure from Poplar Leaf Activated by KHCO3 and Its Efficient Adsorption of Oxytetracycline Hydrochloride.

The effective removal of oxytetracycline hydrochloride (OTC) from the water environment is of great importance. Adsorption as a simple, stable, and cost-effective technology is regarded as an important method for removing OTC. Herein, a low-cost biochar with a developed mesoporous structure was synthesized via pyrolysis of poplar leaf with potassium bicarbonate (KHCO3) as the activator. KHCO3 can endow biochar with abundant mesopores, but excessive KHCO3 cannot continuously promote the formation of mesoporous structures. In comparison with all of the prepared biochars, PKC-4 (biochar with a poplar leaf to KHCO3 mass ratio of 5:4) shows the highest adsorption performance for OTC as it has the largest surface area and richest mesoporous structure. The pseudo-second-order kinetic model and the Freundlich equilibrium model are more consistent with the experimental data, which implies that the adsorption process is multi-mechanism and multi-layered. In addition, the maximum adsorption capacities of biochar are slightly affected by pH changes, different metal ions, and different water matrices. Moreover, the biochar can be regenerated by pyrolysis, and its adsorption capacity only decreases by approximately 6% after four cycles. The adsorption of biochar for OTC is mainly controlled by pore filling, though electrostatic interactions, hydrogen bonding, and π-π interaction are also involved. This study realizes biomass waste recycling and highlights the potential of poplar leaf-based biochar for the adsorption of antibiotics.

Hybrid Composite of Sn(IV)-Porphyrin and Mesoporous Structure for Enhanced Visible Light Photocatalytic Degradation of Organic Dyes.

Two hybrid composites (SnP@MCM-41 and SnP@SiO2) were fabricated by chemical adsorption of (trans-dihydroxo)(5,10,15,20-tetraphenylporphyrinato)tin(IV) (SnP) on mesoporous structured Mobil Composition of Matter No. 41 (MCM-41) and SiO2 nanoparticles. These materials were characterized by Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, fluorescence spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy techniques. The incorporation of SnP into MCM-41 and SiO2 supports efficient photocatalytic degradation of the anionic erioglaucine, cationic rhodamine B, and neutral m-cresol purple dyes under visible light irradiation in an aqueous solution. The performances of degradation of these dyes by these photocatalysts under visible light irradiation varied from 87 to 95%. The pseudo-first-order degradation rate constant of organic dyes for SnP@MCM-41 was higher than those of SnP@SiO2 and SnP. These visible light photocatalysts showed remarkable stability and reliable reusability.

Tuning Mass Transport in Electrocatalysis Down to Sub-5†nm through Nanoscale Grade Separation.

Nano and single-atom catalysis open new possibilities of producing green hydrogen (H2 ) by water electrolysis. However, for the hydrogen evolution reaction (HER) which occurs at a characteristic reaction rate proportional to the potential, the fast generation of H2 nanobubbles at atomic-scale interfaces often leads to the blockage of active sites. Herein, a nanoscale grade-separation strategy is proposed to tackle mass-transport problem by utilizing ordered three-dimensional (3d) interconnected sub-5 nm pores. The results reveal that 3d criss-crossing mesopores with grade separation allow efficient diffusion of H2 bubbles along the interconnected channels. After the support of ultrafine ruthenium (Ru), the 3d mesopores are on a superior level to two-dimensional system at maximizing the catalyst performance and the obtained Ru catalyst outperforms most of the other HER catalysts. This work provides a potential route to fine-tuning few-nanometer mass transport during water electrolysis.

General Synthetic Strategy to Ordered Mesoporous Carbon Catalysts with Single-Atom Metal Sites for Electrochemical CO2 Reduction.

The electrochemical carbon dioxide reduction reaction (CO2 RR) is a transformative technology to reduce the carbon footprint of modern society. Single-site catalysts have been demonstrated as promising catalysts for CO2 RR, but general synthetic methods for catalysts with high surface area and tunable single-site metal composition still need to be developed to unambiguously investigate the structure-activity relationship crossing various metal sites. Here, a generalized coordination-condensation strategy is reported to prepare single-atom metal sites on ordered mesoporous carbon (OMC) with high surface areas (average 800 m2  g-1 ). This method is applicable to a broad range of metal sites (Fe, Co, Ni, Cu, Pt, Pd, Ru, and Rh) with loadings up to 4 wt.%. In particular, the CO2 RR to carbon monoxide (CO) Faradaic efficiency (FE) with Ni single-site OMC catalyst reaches 95%. This high FE is maintained even under large current density (>140 mA cm-2 ) and in a long-term study (14 h), which suits the urgently needed large-scale applications. Theoretical calculations suggest that the enhanced activity on single-atom Ni sites results from balanced binding energies between key intermediates, COOH and CO, for CO2 RR, as mediated by the coordination sphere.

Rare earth Y doping induced lattice strain of mesoporous PtPd nanospheres for alkaline oxygen reduction electrocatalysis.

The synthesis of catalysts with controllable morphology and composition is important to enhance the catalytic performance for oxygen reduction reaction (ORR). Herein, trimetallic PtPdY mesoporous nanospheres (PtPdY MNs) are produced via a one-step chemical reduction method applying F127 as soft temple under acidic condition. The mesoporous structure provides a large contact area and also stimulates the diffusion and mass transfer of reactants and products. Besides, synergistic effect among Pt, Pd and Y elements effectively alters their electronic structure, enhancing the catalytic activity. Therefore, the PtPdY MNs show excellent ORR permanence to Pt/C under the alkaline solution. This study offers an effective channel for the preparation of mesoporous metals with rare earth metal doping towards promising electrocatalytic applications.

Surface Chemistry and Mesopore Dual Regulation by Sulfur-Promised High Volumetric Capacity of Ti3 C2 Tx Films for Sodium-Ion Storage.

Electrochemical sodium-ion storage has come out as a promising technology for energy storage, where the development of electrode material that affords high volumetric capacity and long-term cycling stability remains highly desired yet a challenge. Herein, Ti3 C2 Tx (MXene)-based films are prepared by using sulfur (S) as the mediator to modulate the surface chemistry and microstructure, generating S-doped mesoporous Ti3 C2 Tx films with high flexibility. The mesoporous architecture offers desirable surface accessibility without significantly sacrificing the high density of Ti3 C2 Tx film. Meanwhile, the surface sulfur doping of Ti3 C2 Tx favors the diffusion of sodium ions. These merits are of critical importance to realize high volumetric capacity of the electrode material. As a consequence, as the freestanding electrode material for electrochemical sodium-ion storage, the S-doped mesoporous Ti3 C2 Tx film exhibits a high volumetric capacity of 625.6 mAh cm-3 at 0.1 A g-1 , which outperforms that of many reported electrodes. Moreover, outstanding rate capability and excellent long-term cycling stability extending 5000 cycles are achieved. The work opens the door for innovative design and rational fabrication of MXene-based films with ultrahigh volumetric capacity for sodium-ion storage.

Properties of mesoporous hybrid perovskite nanocrystals and its application in light-emitting diodes.

We fabricated mesoporous perovskite nanocrystal for the first time, and investigated its optical properties and application in light-emitting diodes (LEDs). The transformation of mesoporous structure can be ascribed to the decomposition of nanocrystals under dilution condition, which results in the blueshift of luminescence. The mesoporous nanocrystals under proper dilution may achieve improved perovskite LEDs, with maximum luminance and current efficiency of 23370 cd m-2and 6.7 cd A-1, respectively. This work provide an avenue to the optical engineering of perovskite nanocrystals, and demonstrate that perovskite concentration is one of key factors for realizing efficient LEDs.

Engineering of Coordination Environment and Multiscale Structure in Single-Site Copper Catalyst for Superior Electrocatalytic Oxygen Reduction.

Herein, we report efficient single copper atom catalysts that consist of dense atomic Cu sites dispersed on a three-dimensional carbon matrix with highly enhanced mesoporous structures and improved active site accessibility (Cu-SA/NC(meso)). The ratio of +1 to +2 oxidation state of the Cu sites in the Cu-SA/NC(meso) catalysts can be controlled by varying the urea content in the adsorption precursor, and the activity for ORR increases with the addition of Cu1+ sites. The optimal Cu1+-SA/NC(meso)-7 catalyst with highly accessible Cu1+ sites exhibits superior ORR activity in alkaline media with a half-wave potential (E1/2) of 0.898 V vs RHE, significantly exceeding the commercial Pt/C, along with high durability and enhanced methanol tolerance. Control experiments and theoretical calculations demonstrate that the superior ORR catalytic performance of Cu1+-SA/NC(meso)-7 catalyst is attributed to the atomically dispersed Cu1+ sites in catalyzing the reaction and the advantage of the introduced mesoporous structure in enhancing the mass transport.

Two-Dimensional MXene-Polymer Heterostructure with Ordered In-Plane Mesochannels for High-Performance Capacitive Deionization.

The application of traditional electrode materials for high-performance capacitive deionization (CDI) has been persistently limited by their low charge-storage capacities, excessive co-ion expulsion and slow salt removal rates. Here we report a bottom-up approach to the preparation of a two-dimensional (2D) Ti3 C2 Tx MXene-polydopamine heterostructure having ordered in-plane mesochannels (denoted as mPDA/MXene). Interfacial self-assembly of mesoporous polydopamine (mPDA) monolayers on MXene nanosheets leads to the mPDA/MXene heterostructure, which exhibits several unique features: (1) MXene undergoes reversible ion intercalation/deintercalation and possesses high conductivity; (2) mPDA layers establish redox capacitive characteristics and Na+ selectivity, and also help to prevent self-stacking and oxidation of MXene; (3) in-plane mesochannels enable the smooth transport of ions at the internal spaces of this stacked 2D material. When applied as an electrode material for CDI, mPDA/MXene nanosheets exhibit top-level CDI performance and cycling stability compared to those of the so far reported 2D materials. Our study opens an avenue for the rational construction of MXene-organic hybrid heterostructures, and further motivates the development of high-performance CDI electrode materials.

Targeted immobilization of titanium (IV) on magnetic mesoporous nanomaterials derived from metal-organic frameworks for high-efficiency phosphopeptide enrichment in biological samples.

A selectively modified porous metal/carbon nanocomposite was fabricated to enhance the enrichment of low-abundance phosphopeptides from biological samples. The carbon matrix derived from the metal-organic framework provides a suitable pore size to allow the diffusion of peptides, while the deliberately modified metal nanoparticles within the pores enhance their interaction with the phosphopeptides. This nanocomposite shows extremely high enrichment selectivity for phosphopeptides in the MALDI-TOF MS detection, even when the molar ratio of α-casein digests versus bovine serum albumin digests was up to about 1:20,000. By combining such nanocomposite with nano-LC-MS/MS, 4556 unique phosphopeptides were identified with high selectivity (95.2%) from HeLa cell extracts. Furthermore, phosphopeptides from prostate tissue digests were also determined. A total of 277 and 1242 phosphopeptides were identified from normal and tumor tissues of a patient with prostate cancer, respectively. This indicates that phosphorylation and prostate cancer can be related to each other.

Graphene Quantum Dots-Mediated Theranostic Penetrative Delivery of Drug and Photolytics in Deep Tumors by Targeted Biomimetic Nanosponges.

Dual-targeted delivery of drugs and energy by nanohybrids can potentially alleviate side effects and improve the unique features required for precision medicine. To realize this aim, however, the hybrids which are often rapidly removed from circulation and the piled up tumors periphery near the blood vessels must address the difficulties in low blood half-lives and tumor penetration. In this study, a sponge-inspired carbon composites-supported red blood cell (RBC) membrane that doubles as a stealth agent and photolytic carrier that transports tumor-penetrative agents (graphene quantum dots and docetaxel (GQD-D)) and heat with irradiation was developed. The RBC-membrane enveloped nanosponge (RBC@NS) integrated to a targeted protein that accumulates in tumor spheroids via high lateral bilayer fluidity exhibits an 8-fold increase in accumulation compared to the NS. Penetrative delivery of GQDs to tumor sites is actuated by near-infrared irradiation through a one-atom-thick structure, facilitating penetration and drug delivery deep into the tumor tissue. The synergy of chemotherapy and photolytic effects was delivered by the theranostic GQDs deep into tumors, which effectively damaged and inhibited the tumor in 21 days when treated with a single irradiation. This targeted RBC@GQD-D/NS with the capabilities of enhanced tumor targeting, NIR-induced drug penetration into tumors, and thermal ablation for photolytic therapy promotes tumor suppression and exhibits potential for other biomedical applications.

Molecularly imprinted mesoporous silica incorporating C3N4 dots and CdTe quantum dots as ratiometric fluorescent probe for determination of Malachite Green.

A new dual-emission ratiometric fluorescent probe was synthesized and successfully used for the determination of Malachite Green (MG) in fish farming water. The ratiometric fluorescent probe was successfully composited by sol-gel method using C3N4 and CdTe quantum dots as fluorescent materials combined with mesoporous molecularly imprinted polymers. MG quenches the red fluorescence of the CdTe QDs (with excitation/emission wavelengths at 350/680 nm) while the blue fluorescence of C3N4 (with excitation/emission wavelengths at 350/458 nm) remains unchanged. The change of fluorescence color and fluorescence intensity ratio can be successfully used for quantification of malachite green. In addition, the mesoporous structure has a large surface and good adsorption capacity for malachite green. The normalized intensity of fluorescence increases linearly in the 50-1000 ng·mL-1 MG concentration range, and the detection limit is 10 ng·mL-1. The imprinting factor is 3.2. The nanoprobe was applied to the determination of MG in fish farming water samples. Recoveries and relative standard deviations were 92.5-97.8% and 2.5-6.2%, respectively. Graphical abstract Schematic representation of synthesis of molecularly imprinted mesoporous silica ratiometric fluorescent probes incorporating C3N4 dots and CdTe quantum dots for determination of malachite green.

The Influence of PEG 4000 on the Physical and Microstructural Properties of 58S Bioactive Glasses.

Bioactive glass is currently considered a material with a high biocompatibility and has been used both in the field of bone regeneration and in the preparation of cosmetic products with the controlled release of active compounds. The present work involved a study on the synthesis of bioglass using the sol-gel process. The study aims to evaluate the influence of the treatment of bioglass with Polyethylene glycol 4000 (PEG 4000) on its main characteristics. The surface characteristics of this material were obtained by nitrogen adsorption/desorption analysis, using the standard BET (Brunauer-Emmett-Teller) equation, the crystallinity by XRD (X-ray diffraction) analysis, the surface structure by SEM (Scanning Electron Microscope), thermal stability by TGA (ThermoGravimetric Analyses), and chemical bonds changes by FTIR (Fourier transform infrared) spectroscopy. After treatment with PEG 4000, the average diameter of the pores increased insignificantly, the crystallinity peak disappeared, and the SEM analysis highlighted several clusters of very small sizes.