Rapid start-up of carbon-free H2 production by ammonia oxidative decomposition over Co/Ce0.5Zr0.5O2 with microwave irradiation.

Hydrogen is a promising combustion improver for use with ammonia fuels, but a cost-effective method for easily producing hydrogen from ammonia at a high rate has yet to be developed. Here, we show that microwave irradiation instantly triggers oxidative decomposition of ammonia over a Co/Ce0.5Zr0.5O2 catalyst to produce hydrogen at a high rate. The microwave irradiation rapidly heats the inside of the catalyst from room temperature to the catalytic auto-ignition temperature of ammonia, thus initiating exothermic oxidative decomposition of ammonia to produce hydrogen. This method provides a highly efficient means of producing hydrogen for potential use in a carbon-free, ammonia-fueled power generation process.

Direct and stable hydrogenation of CO2 to aromatics over a tandem catalyst Zn0.1Ti0.9Ox/HZSM-5.

Direct and stable conversion of CO2 to aromatics (CTA) is an attractive route for reducing CO2 emissions. However, due to the chemical inertness of CO2, direct CTA reaction with high aromatics selectivity is still challenging. In this work, a tandem catalyst Zn0.1Ti0.9Ox/HZSM-5 with appropriate density and strength of acid sites exhibits a high aromatics selectivity of 67.2% and long-term stability over 100 h. Furthermore, the total selectivity of benzene, toluene, and xylene achieves 24.1% over Zn0.1Ti0.9Ox/HZSM-5 with a modified hydrophilic surface. In addition, the CTA via the formate route has been determined in this reaction system.

Leaflet-heterostructures by MWCNT self-assembly following electrospinning.

Electrospinning of nanocarbons such as graphene and carbon nanotubes typically produces mats composed of one-dimensional fibers where the carrier polymer encapsulates the nanocarbons. Recently it was found that decreasing the amount of carrier polymer in approaching the electrospinning-electrospray boundary for graphene suspensions resulted in retention of the graphene two-dimensional anisotropy with one-dimensional carrier polymer fibers connecting flakes. We explored a similar decrease in carrier polymer in MWCNT suspensions to investigate the network topology that might ensue. Unexpectedly, two-dimensional leaflet meso-networks were obtained wherein the leaflets comprise laterally aligned MWCNTs one to several nanotubes thick. A mechanism based on capillary force-driven MWCNT self-assembly activated by menisci formed during drying of electrospun fibers is presented. Such materials offer new approaches to producing high surface-area coatings for catalytic and energy applications and suggest ways of formulating two-dimensional MWCNT assemblies in metal foams and other open-cell porous materials.

ZnO nanoparticles encapsulated cellulose-lignin film for antibacterial and biodegradable food packaging.

Foodborne illness caused by consuming foods contaminated by pathogens remains threating to the public health. Despite considerable efforts of using renewable source materials, it is highly demanding to fabricate food packaging with multiple properties including eco-friendliness, bactericidal effect and biocompatibility. Here, sodium lignosulfonate (SL) and ZnO nanoparticles (ZnO NPs) were used as functional filler and structure components, respectively, on the cellulose nanofibers (CNFs)-based films, which endows the produced membrane (CNF/SL-ZnO) the UV-light blocking, antioxidant, and antimicrobial characteristics. Due to the interconnected polymeric structure, the prepared CNF/SL-ZnO films possessed considerable mechanical properties, thermal stability, and good moisture barrier capability. Moreover, the tested samples exhibited an improved shelf life in food packaging. Furthermore, metagenome analysis revealed superior biodegradability of obtained films with negligible side effect on the soil microenvironment. Therefore, the biocompatible, degradable, and antibacterial CNF/SL-ZnO film holds enormous potential for sustainable uses including food packaging.

Controlling Triboelectric Charge of MOFs by Leveraging Ligands Chemistry.

Metal-organic frameworks (MOFs) have emerged as promising materials for triboelectric nanogenerators (TENGs), but the effects of ligand choice on triboelectric charge remain underexplored. Hence, this paper demonstrates the effect of single, binary, and ternary ligands on TENG performance of cobalt/cerium-based (Co─Ce) bimetallic MOFs utilizing 2-methylimidazole (2Melm), terephthalic acid (BDC), and benzene tricarboxylic acid (BTC) as ligands. The detailed structural characterization revealed that varying ligand chemistries led to distinct MOF features affecting TENG performance. Single ligand bimetallic MOFs (designated as CoCe-2MeIm, CoCe-BDC, CoCe-BTC) has lower performance than binary ligand (designated as CoCe-2MeIm-BDC, CoCe-2MeIm-BTC, CoCe-BDC-BTC) and ternary ligand MOFs (designated as CoCe-2MeIm-BDC-BTC). Among all, the binary ligand MOF, CoCe-2MeIm-BTC, shows the best results (598 V, 26.7 µA) due to the combined effect of imidazole ring and (─COO─) groups. This is attributed to lone pairs on nitrogen atoms and a delocalized π-electron system in imidazole system in this material. CoCe-BTC has the lowest results (31 V, 3.2 µA) due to the bulkier nature of the electron-withdrawing (─COO─) groups and their impact on the π-electron system of the benzene ring. This study showcases the potential of ligand chemistry manipulation to control triboelectric charge and thereby enhance MOF-based TENG performance.

Synergistic effects of oxygen vacancies and mesoporous structures in amorphous C@TiO2 for photocatalytic CO2 reduction.

In this study, the theoretical calculations proves that the combination of oxygen vacancy and amorphous carbon films in TiO2 (VO-CT) can effectively reduce the energy bandgap and work function. The minimum Gibbs free energies required for the CO2RR reaction of VO-CT are 0.20 eV, which is lower than pure TiO2. The amorphous c@TiO2 nanomaterials with oxygen vacancy and mesoporous structures (VO-MCT) are prepared with the P123 surfactant as the template and oxalic acid as an inducer. The electron paramagnetic resonance indicates the presence of abundant oxygen vacancy defects in the samples. UV-vis spectra indicate that the mesoporous structure enhances light absorption capacity. The photocatalytic CO2 reduction tests show that the highest conversion rates for CH4 and CO of VO-MCT are 14 µmol g-1 h-1 and 10.66 µmol g-1 h-1, respectively. The electron consumption rate of VO-MCT is 12.43 times higher than that of commercial TiO2 (P200).

Mechanoactivated amorphization and photopolymerization of styryldipyryliums.

Conventional topochemical photopolymerization reactions occur exclusively in precisely-engineered photoactive crystalline states, which often produces high-insoluble polymers. To mitigate this, here, we report the mechanoactivation of photostable styryldipyrylium-based monomers, which results in their amorphization-enabled solid-state photopolymerization and produces soluble and processable amorphous polymers. A combination of solid-state nuclear magnetic resonance, X-ray diffraction, and absorption/fluorescence spectroscopy reveals the crucial role of a mechanically-disordered monomer phase in yielding polymers via photo-induced [2 + 2] cycloaddition reaction. Hence, mechanoactivation and amorphization can expand the scope of topochemical polymerization conditions to open up opportunities for generating polymers that are otherwise difficult to synthesize and analyze.

Composition effects of electrodeposited Cu-Ag nanostructured electrocatalysts for CO2 reduction.

The electrochemical carbon dioxide reduction (CO2RR) on Cu-based catalysts is a promising strategy to store renewable electricity and produce valuable C2+ chemicals. We investigate the CO2RR on Cu-Ag nanostructures that have been electrodeposited in a green choline chloride and urea deep eutectic solvent (DES). We determine the electrochemically active surface area (ECSA) using lead underpotential deposition (UPD) to investigate the CO2RR intrinsic activity and selectivity. We show that the addition of Ag on electrodeposited Cu primarily suppresses the production of hydrogen and methane. While the production of carbon monoxide slightly increases, the partial current of the total C2+ products does not considerably increase. Despite that the production rate of C2+ is similar on Cu and Cu-Ag, the addition of Ag enhances the formation of alcohols and oxygenates over ethylene. We highlight the potential of metal electrodeposition from DES as a sustainable strategy to develop bimetallic Cu-based nanocatalysts for CO2RR.

Co-Cu nanoparticles uniformly embedded in the intra-crystalline mesoporous Silicalite-1 for catalytic ammonia borane hydrolysis.

Zeolite-encaged metal nanoparticles (NPs) catalysts are emerging as a new frontier owing to their superior ability to stabilize the structure and catalytic performance in the thermal and environmental catalytic reaction. However, the pore size below 2 nm of the conventional zeolites usually limits the accessibility of metal active sites. Herein, Co-Cu NPs of about 2.5-3.5 nm were uniformly encapsulated in the intracrystalline mesoporous Silicalite-1 (S-1) through alkali-treatment ligand-assisted strategy. The obtained sample (termed CoxCu1-x@HS-1) exhibited efficient activity and stability in the ammonia borane hydrolysis with the highest TOF value of 21.46 molH2·molMe-1·min-1. UV-vis DRS spectra indicated that intracrystalline mesopores have greatly improved the openness and accessibility of the active sites, thus improving their catalytic performance. The introduction of Cu regulates the electronic properties of Co, further increasing hydrogen production activity. This research creates new prospects to design other high-performance hierarchical porous zeolite-confined metal/metal oxide catalysts.

Zr modulated N doping composites for CO2 conversion into carbonates.

Acidic and basic sites of catalysts are essential for CO2 capture and activation. In this work, Zr, N-ZnO/ZnAl-LDH-IL composites in ionic liquid and methanol systems were fabricated, and applied to catalyze the synthesis of ethylene carbonate (EC) from ethylene glycol (EG) and CO2 with about 4.76 mmolEC gCat.-1 h-1. The composites showed more strong basic sites due to the effective induction of reactive groups on the catalyst surface by Zr doping, resulting in an increase of pyridinic-N groups from 5.48% to 22.25%. More C atoms adjacent to pyridinic-N as strong basic sites was conducive to the activation of CO2 and EG. In addition, the possible catalytic pathway and mechanism of the composites for synthesizing EC as well as the doping of La, Fe, Ce, and Cu were also investigated, which provides an effective strategy for regulating the acid-base centers on the catalyst surface through ionic liquids and methanol solvents.

Insights into the hydrogen generation and catalytic mechanism on Co-based nanocomposites derived from pyrolysis of organic metal precursor.

Hydrogen generation from boron hydride is important for the development of hydrogen economy. Cobalt (Co) element has been widely used in the hydrolysis of boron hydride. Pyrolysis is a common method for materials synthesis in catalytic fields. Herein, Co-based nanocomposites derived from the pyrolysis of organic metal precursors and used for hydrolysis of boron hydride are summarized and discussed. The different precursors consisting of MOF, supported, metal, and metal phosphide precursors are summarized. The catalytic mechanism consisting of dissociation mechanism based on oxidative addition-reduction elimination, pre-activation mechanism, SN2 mechanism, four-membered ring mechanism, and acid-base mechanism is intensively discussed. Finally, conclusions and outlooks are conveyed from the design of high-efficiency catalysts, the characterization of catalyst structure, the enhancement of catalytic activities, the investigation of the catalytic mechanism, and the catalytic stability of active structure. This review can provide guidance for designing high-efficiency catalysts and boosting development of hydrogen economy.

Highly efficient hydrodesulfurization driven by an in-situ reconstruction of ammonium/amine intercalated MoS2 catalysts.

Hydrodesulfurization (HDS) is a commonly used route for producing clean fuels in modern refinery. Herein, ammonium/amine-intercalated MoS2 catalysts with various content of 1T phase and S vacancies have been successfully synthesized. Along with the increment of 1T phase and S vacancies of MoS2, the initial reaction rate of the HDS of dibenzothiophene (DBT) can be improved from 0.09 to 0.55 µmol·gcat-1·s-1, accounting for a remarkable activity compared to the-state-of-the-art catalysts. In a combinatory study via the activity evaluation and catalysts characterization, we found that the intercalation species of MoS2 played a key role in generating more 1T phase and S vacancies through the 'intercalation-deintercalation' processes, and the hydrogenation and desulfurization of HDS can be significantly promoted by 1T phase and S vacancies on MoS2, respectively. This study provides a practically meaningful guidance for developing more advanced HDS catalysts by the intercalated MoS2-derived materials with an in-depth understanding of structure-function relationships.

Precise regulation of phosphorus in nitrogen-coordinated porous carbon spheres for tunable CO2 electroreduction to syngas.

The production of high-demand syngas with tunable ratios by CO2 electroreduction has attracted considerable research interest. However, it is challenging to balance the evolution performance of H2 and CO with wide H2/CO ratios, while maintaining high efficiency. Herein, nitrogen-coordinated hierarchical porous carbon spheres with varying phosphorus content (PxNC-T) are assembled to regulate syngas production performance. The precise introduction of P modulates the local charge distribution of nitrogen-coordinated carbons, thereby accelerating the protonation process of ∗CO2-to-∗COOH and promoting moderate H∗ adsorption. Specifically, syngas with wide H2/CO ratios (0.60-4.98) is obtained over a low potential range (-0.46 to -0.86 V vs. RHE). As a representative, P1.0NC-900 presents a remarkable current density (-152 mA cm-2) at -1.0 V vs. RHE in flow cells and delivers a decent peak power density (1.93 mW cm-2) in reversible Zn-CO2 batteries. Our work provides valuable insights into the rational design of carbon-based catalysts for CO2 reduction.

The frontier of tungsten oxide nanostructures in electronic applications.

Electrochromic (EC) glazing has garnered significant attention recently as a crucial solution for enhancing energy efficiency in future construction and automotive sectors. EC glazing could significantly reduce the energy usage of buildings compared to traditional blinds and glazing. Despite their commercial availability, several challenges remain, including issues with switching time, leakage of electrolytes, production costs, etc. Consequently, these areas demand more attention and further studies. Among inorganic-based EC materials, tungsten oxide nanostructures are essential due to its outstanding advantages such as low voltage demand, high coloration coefficient, large optical modulation range, and stability. This review will summarize the principal design and mechanism of EC device fabrication. It will highlight the current gaps in understanding the mechanism of EC theory, discuss the progress in material development for EC glazing, including various solutions for improving EC materials, and finally, introduce the latest advancements in photo-EC devices that integrate photovoltaic and EC technologies.

Metal chloride cathodes for next-generation rechargeable lithium batteries.

Rechargeable lithium-ion batteries (LIBs) have prospered a rechargeable world, predominantly relying on various metal oxide cathode materials for their abilities to reversibly de-/intercalate lithium-ion, while also serving as lithium sources for batteries. Despite the success of metal oxide, issues including low energy density have raised doubts about their suitability for next-generation lithium batteries. This has sparked interest in metal chlorides, a neglected cathode material family. Metal chlorides show promise with factors like energy density, diffusion coefficient, and compressibility. Unfortunately, challenges like high solubility hamper their utilization. In this review, we highlight the opportunities for metal chlorides in the post-lithium-ion era. Subsequently, we summarize their dissolution challenges. Furthermore, we discuss recent advancements, encompassing liquid-state electrolyte engineering, solid-state electrolytes (SSEs) cooperation, and LiCl-based cathodes. Finally, we provide an outlook on future research directions of metal chlorides, emphasizing electrode fabrication, electrolyte design, the application of SSEs, and the exploration of conversion reactions.

Synergistic effect between transition metal single atom and SnS2 toward deep CO2 reduction.

The electrochemical reduction of CO2 is an efficient channel to facilitate energy conversion, but the rapid design and rational screening of high-performance catalysts remain a great challenge. In this work, we investigated the relationships between the configuration, energy, and electronic properties of SnS2 loaded with transition metal single atom (TM@SnS2) and analyzed the mechanism of CO2 activation and reduction by using density functional theory. The "charge transfer bridge" promoted the adsorption of CO2 on TM@SnS2, thus enhancing the binding of HCOOH∗ to the catalyst for further hydrogenation and reduction to high-value CH4. The research revealed that the binding free energy of COOH∗ on TM@SnS2 formed a "volcano curve" with the limiting potential of CO2 reduction to CH4, and the TM@SnS2 (TM = Cr, Ru, Os, and Pt) at the "volcano top" exhibited a high CH4 activity.

Application of metal-organic frameworks and their derivates for thermal-catalytic C1 molecules conversion.

One-carbon (C1) catalysis refers to the conversion of compounds with a single carbon atom, especially carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4), into clean fuels and valuable chemicals via catalytic strategy is crucial for sustainable and green development. Among various catalytic strategies, thermal-driven process seems to be one of the most promising pathways for C1 catalysis due to the high efficiency and practical application prospect. Notably, the rational design of thermal-driven C1 catalysts plays a vital role in boosting the targeted products synthesis of C1 catalysis, which relies heavily on the choice of ideal active site support, catalyst fabrication precursor, and catalytic reaction field. As a novel crystalline porous material, metal-organic frameworks (MOFs) has made significant progress in the design and synthesis of various functional nanomaterials. However, the application of MOFs in C1 catalysis faces numerous challenges, such as thermal stability, mechanical strength, yield of MOFs, and so on. To overcome these limitations and harness the advantages of MOFs in thermal-driven C1 catalysis, researchers have developed various catalyst/carrier preparation strategies. In this review, we provide a concise overview of the recent advancements in the conversion of CO, CO2, and CH4 into clean fuels and valuable chemicals via thermal-catalytic strategy using MOFs-based catalysts. Furthermore, we discuss the main challenges and opportunities associated with MOFs-based catalysts for thermal-driven C1 catalysis in the future.

Binder assisted graphene derivatives as lubricants in copper: Improved tribological performance for industrial application.

Originally derived from graphite, high-quality single-layer graphene is an excellent anti-wear and -friction additive in metal matrix. Here, the tribological performance of 3 different commercialized graphene derivatives (e.g., graphene oxide [GO], reduced graphene oxide [RGO], and graphene nanoplatelet [GNP]) as additives in a Cu matrix, were investigated from an industrial perspective. To increase the interaction of graphene derivatives with Cu particles, and addressing the aggregation problem of the graphene derivatives, different binders (polyvinyl alcohol [PVA] and cellulose nanocrystals [CNC]) were introduced into the system. Benefiting from such a strategy, a uniform distribution of the graphene derivatives in Cu matrix was achieved with graphene loading up to 5 wt %. After high-temperature sintering, the graphene is preserved and well distributed in the Cu matrix. It was found that the GNP-containing sample shows the most stable friction coefficient behavior. However, GO and RGO also improve the tribological performance of Cu under different circumstances.

Unique activity of a Keggin POM for efficient heterogeneous electrocatalytic OER.

Polyoxometalates (POMs) have been well studied and explored in electro/photochemical water oxidation catalysis for over a decade. The high solubility of POMs in water has limited its use in homogeneous conditions. Over the last decade, different approaches have been used for the heterogenization of POMs to exploit their catalytic properties. This study focused on a Keggin POM, K6[CoW12O40], which was entrapped in a sol-gel matrix for heterogeneous electrochemical water oxidation. Its entrapment in the sol-gel matrix enables it to catalyze the oxygen evolution reaction at acidic pH, pH 2.0. Heterogenization of POMs using the sol-gel method aids in POM's recyclability and structural stability under electrochemical conditions. The prepared sol-gel electrode is robust and stable. It achieved electrochemical water oxidation at a current density of 2 mA/cm2 at a low overpotential of 300 mV with a high turnover frequency (TOF) of 1.76 [mol O2 (mol Co)-1s-1]. A plausible mechanism of the electrocatalytic process is presented.

Hybridized nanozymes for anti-osteosarcoma therapy via the Fenton reaction.

Abnormal accumulation of hydrogen peroxide (H2O2) in the tumor microenvironment is associated with altered metabolism, abnormal proliferation of tumor cells, and changes in the tumor microenvironment. Based on this phenomenon, we have developed manganese-doped zeolitic imidazolate frameworks (Mn-ZIF) nanozymes, which exhibit superior peroxidase (POD)-like activity and enhanced cytotoxicity. Inside the tumor, the H2O2 is catalyzed by Mn-ZIF nanozymes through the Fenton reaction to generate more potent hydroxyl radicals (·OH), further increasing the local reactive oxygen species (ROS) levels in tumor cells and inducing tumor cell death. Meanwhile, the removal of H2O2 in the tumor microenvironment reduces tumor proliferation. We have confirmed the anti-tumor effect of these particles in an in situ osteosarcoma (OS) model, providing a direction for the future design of hybrid nanozyme drug delivery systems.