Borocarbonitride Catalyzed Ethylbenzene Oxidative Dehydrogenation: Activity Enhancement via Encapsulation of Mn Clusters inside the Tube.

Borocarbonitride (BCN) catalysts, boasting multiple redox sites, have shown considerable potential in alkane oxidative dehydrogenation (ODH) to olefin molecules. However, their catalytic efficiency still lags behind that of leading commercial catalysts, primarily due to the limited reactivity of oxygen functional groups. In this study, a groundbreaking hybrid catalyst is developed, featuring BCN nanotubes (BCNNTs) encapsulated with manganese (Mn) clusters, crafted through a meticulous supramolecular self-assembly and postcalcination strategy. This novel catalyst demonstrates a remarkable enhancement in activity, achieving 30% conversion and ≈100% selectivity toward styrene in ethylbenzene ODH reactions. Notably, its performance surpasses both pure BCNNTs and those hosting Mn nanoparticles. Structural and kinetic analyses unveil a robust interaction between BCNNTs and the Mn component, substantially boosting the catalytic activity of BCNNTs. Furthermore, density functional theory (DFT) calculations elucidate that BCNNTs encapsulated with Mn clusters not only stabilize key intermediates (─B─O─O─B─) but also enhance the nucleophilicity of active sites through electron transfer from the Mn cluster to the BCNNTs. This electron transfer mechanism effectively lowers the energy barrier for ─C─H cleavage, resulting in a 13% improvement in catalytic activity compared to pure BCNNTs.

Fabrication of Oriented MOF-Based Mixed Matrix Membrane via Ion-Induced Synchronous Synthesis.

Developing a facile strategy for constructing oriented mixed matrix membranes (MMMs) with uniformly dispersed and high-loading metal-organic frameworks (MOFs) is a crucial scientific challenge in probing the enhanced capability and potential applications of MOF-polymer MMMs. Herein, a novel synchronous synthetic method for constructing oriented CuBDC/poly(m-phenylenediamine) (CuBDC/PmPD) MMM with uniform MOF dispersion at high loading at the air-solution interface via the dual function of metal ions is reported. The resulting MMM exhibits excellent separation performance in ion sieving and seawater desalination due to the structural integrity of the proposed membrane and the highly interconnected channels created through the oriented distribution of MOF in a polymer matrix. Such a cutting-edge approach may provide promising insights into the development of advanced MMMs with optimized structure and superior performances.

Redox Concomitant Formation Method for Fabrication of Cu(I)-MOF/Polymer Composites with Antifouling Properties.

Marine biofouling, which is one of the technical challenges hindering the growth of the marine economy, has been controlled using cuprous oxide (Cu2O) nanoparticles due to the exceptional antifouling properties of Cu(I) ions. However, Cu2O nanoparticles have encountered bottlenecks due to explosive releases of Cu+ ions, high toxicity at elevated doses, and long-term instability. Here, we present a novel method called Redox Concomitant Formation (RCF) for fabricating a hierarchical Cu(I) metal-organic framework polypyrrole (Cu(I)-MOF/PPy) composite. This method enables in-situ phase transition via successive redox reactions that change the chemical valence state and coordination mode of Cu(II)-MOF, resulting in a new structure of Cu(I)-MOF while creating a PPy layer surrounded by the hierarchical structure. Owing to the steady release of Cu+ ions from the Cu(I) sites and photothermal properties of PPy, Cu(I)-MOF/PPy exhibits superior and broad-spectrum resistance to marine bacteria, algae, and surface-adhered biofilms in complex biological environments, as well as long-term stability, resulting in 100% eradication efficiency under solar-driven heating. Mechanistic insights into successive structural redox reactions and formation using the RCF method are provided in detail, enabling the fabrication of novel MOFs with the desired composition and structure for a wide range of potential applications.

A Tale of Two Sites: Neighboring Atomically Dispersed Pt Sites Cooperatively Remove Trace H2 in CO-Rich Stream.

Single-atom catalysts (SACs) exhibit distinct catalytic behavior compared with nano-catalysts because of their unique atomic coordination environment without the direct bonding between identical metal centers. How these single atom sites interact with each other and influence the catalytic performance remains unveiled as designing densely populated but stable SACs is still an enormous challenge to date. Here, a fabrication strategy for embedding high areal density single-atom Pt sites via a defect engineering approach is demonstrated. Similar to the synergistic mechanism in binuclear homogeneous catalysts, from both experimental and theoretical results, it is proved that electrons would redistribute between the two oxo-bridged paired Pt sites after hydrogen adsorption on one site, which enables the other Pt site to have high CO oxidation activity at mild-temperature. The dynamic electronic interaction between neighboring Pt sites is found to be distance dependent. These new SACs with abundant Pt-O-Pt paired structures can improve the efficiency of CO chemical purification.

Effects of porous structure and oxygen functionalities on electrochemical synthesis of hydrogen peroxide on ordered mesoporous carbon.

Two-electron oxygen reduction reaction (2e- ORR) is a promising alternative to energy-intensive anthraquinone process for hydrogen peroxide (H2O2) production. Metal-free nanocarbon materials have garnered intensive attention as highly prospective electrocatalysts for H2O2 production, and an in-depth understanding of their porous structure and active sites have become a critical scientific challenge. The present research investigates a range of porous carbon catalysts, including non-porous, microporous, and mesoporous structures, to elucidate the impacts of porous structures on 2e- ORR activity. The results highlighted the superiority of mesoporous carbon over other porous materials, demonstrating remarkable H2O2 selectivity. Furthermore, integration of X-ray photoelectron spectroscopy (XPS) data analysis with electrochemical assessment results unravels the moderate surface oxygen content is the key to increase 2e- ORR activity. These results not only highlight the intricate interplay between pore structure and oxygen content in determining catalytic selectivity, but also enable the design of carbon catalysts for specific electrochemical reactions.

Selective electrooxidation of 5-hydroxymethylfurfural to 5-formyl-furan-2-formic acid on non-metallic polyaniline catalysts: structure-function relationships.

The biomass-derived HMF oxidation reaction (HMFOR) holds great promise for sustainable production of fine chemicals. However, selective electrooxidation of HMF to high value-added intermediate product 5-formyl-furan-2-formic acid (FFCA) is still challenging. Herein, we report the electrocatalytic HMFOR to selectively produce FFCA using carbon paper (CP) supported polyaniline (PANI) as a catalyst. The PANI/CP non-metallic hybrid catalyst with moderate oxidation capacity exhibitsoptimized FFCA selectivity up to 76% in alkaline media, which has reached the best performance in reported literature studies. Identification and quantification of active sites for the HMFOR are further realized via linking the activity to structural compositions of PANI; both polaronic-type nitrogen (N3) and positively charged nitrogen (N4) species are proved responsible for adsorption and activation of HMF, and the intrinsic activity of N4 is higher than that of N3. The present work provides new physical-chemical insights into the mechanism of the HMFOR on non-metallic catalysts, paving the way for the establishment of structure-function relations and further development of novel electrochemical synthesis systems.

Nitrogen-Doped Graphene Monolith Catalysts for Oxidative Dehydrogenation of Propane.

It's of paramount importance to develop renewable nanocarbon materials to replace conventional precious metal catalysts in alkane dehydrogenation reactions. Graphene-based materials with high surface area have great potential for light alkane dehydrogenation. However, the powder-like state of the graphene-based materials seriously limits their potential industrial applications. In the present work, a new synthetic route is designed to fabricate nitrogen-doped graphene-based monolith catalysts for oxidative dehydrogenation of propane. The synthetic strategy combines the hydrothermal-aerogel and the post thermo-treatment procedures with urea and graphene as precursors. The structural characterization and kinetic analysis show that the monolithic catalyst well maintains the structural advantages of graphene with relatively high surface area and excellent thermal stability. The homogeneous distributed nitrogen species can effectively improve the yield of propylene (5.3% vs. 1.9%) and lower the activation energy (62.6 kJ mol-1 vs. 80.1 kJ mol-1) in oxidative dehydrogenation of propane reaction comparing with un-doped graphene monolith. An optimized doping amount at 1:1 weight content of the graphene to urea precursors could exhibit the best catalytic performance. The present work paves the way for developing novel and efficient nitrogen-doped graphene monolithic catalysts for oxidative dehydrogenation reactions of propane.