Catalytic methane decomposition (CMD) is a promising route for the co-production of COx-free H-2 and value-added carbon, but its practical application is limited by catalyst deactivation caused by carbon deposition and Ni sintering. In this work, Ni catalysts supported on silica materials with different pore architectures, namely fibrous KCC-1, bimodal porous BPS-5, and channel-type MCM-41 and SBA-15, were systematically compared to clarify the role of support structure in Ni dispersion, carbon deposition, and CMD stability. Among them, Ni(30)/KCC-1 showed the best overall performance, reaching 81.3% CH4 conversion at 800 degrees C and maintaining >50% conversion for more than 180 min at 600 degrees C. The three-dimensional radially fibrous network of KCC-1 favored highly dispersed Ni species, alleviated pore blockage, and promoted the formation of highly graphitized multi-walled carbon nanotubes (I-D/I-G = 0.88). In contrast, MCM-41 and SBA-15 tended to form larger surface Ni particles and deactivated more rapidly, while BPS-5 only partly relieved diffusion limitations. Kinetic analysis over Ni(30)/KCC-1 gave an apparent reaction order of 1.29 and an apparent activation energy of 47.65 kJ mol(-1), indicating high intrinsic CMD activity. These results demonstrate the structural superiority of KCC-1 as a Ni support and provide guidance for designing durable catalysts for low-carbon hydrogen production with simultaneous carbon nanomaterial valorization.

ABSTRACT A fluorine‐free hydrophilic coating was fabricated on polytetrafluoroethylene (PTFE) membranes using sodium dodecylbenzenesulfonate (SDBS), nano‐silica (SiO 2 ), and ethylene‐vinyl alcohol copolymer (EVOH) through a simple immersion–drying process. The modification aimed to improve membrane wettability, permeability, and chemical stability. FTIR, XPS, SEM, and AFM analyses confirmed the formation of a uniform organic–inorganic composite coating. AFM further showed that the characteristic granular morphology and surface roughness changed little after immersion in acidic, alkaline, and oxidative solutions, indicating good nanoscale structural stability under harsh conditions. At the optimal composition (SDBS:SiO 2 :EVOH = 2:1:1), the water contact angle decreased from 124.8° for pristine PTFE to 60.6°, while the pure water flux reached 3727.99 L m −2 h −1 . The modified membrane also exhibited high flux recovery after bovine serum albumin fouling, with a flux recovery ratio of 92.3%. In oil–water separation tests, the membrane achieved separation efficiencies above 98% and maintained stable performance during three consecutive filtration cycles. In addition, stable wettability and permeation performance were retained after 1‐week immersion in solutions ranging from pH 1–14. The results indicate that the EVOH‐stabilized SiO 2 /SDBS coating provides an effective, PFAS‐free, and scalable strategy for preparing durable hydrophilic PTFE membranes under harsh operating conditions.

Formic acid (HCOOH) has received attention as a liquid organic hydrogen carrier (LOHC) due to its ability to decompose into hydrogen and carbon dioxide under mild conditions. Despite its potential, the efficient dehydrogenation of formic acid remains a challenge due to the required presence of a base or additive to facilitate its dehydrogenation. In contrast, the utilization of the corresponding formate salts represents attractive alternatives, since they are non-corrosive, non-irritating, and easier to handle. Herein, we report the catalytic decomposition of sodium formate for hydrogen generation using a ruthenium pincer complex (I) immobilized on highly dehydroxylated silica 700. This complex exhibited a good turnover frequency (TOF = 14735 h- 1) along with excellent selectivity in the decomposition of sodium formate, where surface silanol assisted proton transfer facilitated the generation of hydrogen and carbon dioxide. Furthermore, controlled experimental and Density Functional Theory calculations were employed to elucidate the reaction intermediates, electronic structure, and transition states, offering a deeper mechanistic understanding of the reaction pathway. Overall, this study highlights the dual role of silica support, serving both as a structural support and as an active participant in the reaction as a proton source.

The widespread use of fluorinated silane coupling agents in hydrophobic textile coatings has raised increasing concerns due to their bioaccumulation and environmental persistence. In this study, a series of fluorine-free, POSS-based silane coupling agents were synthesized via hydrosilylation between octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) and two functional silanes-trimethoxyhydrosilane (MTMS) and bis(trimethylsiloxy)methylsilane (MDHM)-with tunable molar ratios. These hybrid silanes were applied to cotton fabric using a simple one-step dip-coating method. Among them, the POSS-4MTMS-4MDHM formulation, at a concentration of 0.2 wt%, imparted superhydrophobicity with a water contact angle (WCA) of 151 degrees and a sliding angle (SA) of 8 degrees. The modified fabric exhibited outstanding mechanical durability, maintaining a WCA of 147 degrees after 100 abrasion cycles under 200 g loading, and retained excellent water repellency after ultrasonic washing and tape-peeling tests. Furthermore, the coating demonstrated chemical resistance over a wide pH range, while preserving the inherent softness and improving the surface smoothness of the fabric. In oil-water separation tests, the coated fabric achieved a separation efficiency of 98.5% and an oil flux of 11.59 L m(-2) s(-1), with efficiency remaining above 97% after 30 reuse cycles. This scalable, fluorine-free strategy enables the fabrication of multifunctional, robust textile coatings with hydrophobic, antifouling, and separation properties.

This study employed nonahydrate ferric nitrate and hexahydrate cobalt nitrate as precursors to fabricate catalysts via calcination, varying the iron-cobalt molar ratios (1: 5, 3: 4, 1: 1, 4: 3, 5: 1). It identified the optimal ratio for catalytic decomposition of methane (CDM) performance. Furthermore, adjusting the calcination temperature enabled control over the spinel content in catalysts with the optimal Fe: Co ratio (3: 4), resulting in a range of single and bimetallic catalysts with diverse spinel contents. Comparative analysis revealed the superior performance of bimetallic catalysts compared to single-metal counterparts. Specifically, under the conditions of 800 degrees C and GHSV 6 L/(gcat.& sdot;h), Fe3Co4-700 degrees C achieved a maximum methane conversion of 75.6%, after maintaining a CDM test for 6 h, there is no decrease in stability. This is because the synergistic effect of Fe and Co bimetallic in the Fe3Co4-700 degrees C catalyst facilitates the transfer of charges between the bimetals, alters the surface charge density of the catalyst, enhances the electron donation capability of active sites, thereby favoring the adsorption and cracking processes of methane. XRD indicates that this catalyst with smaller crystallite size benefits the dispersion of catalytic active sites, thus improving the CDM performance. Results underscored the significant impacts of calcination temperature and metal ratio on the catalyst's spinel content and crystallite size. Characterization of spent catalysts unveiled carbon products primarily comprising carbon nano-onions, graphite, and carbon nanotubes, with the optimal catalyst yielding 5.8 gC/gcat.. Increasing calcination temperatures facilitated the formation of the spinel phase. At 150 degrees C, the Fe: Co (3: 4) catalyst had minimal spinel content, whereas at 300 degrees C, 700 degrees C, and 1000 degrees C, the contents are 9%, 11%, and 24%, respectively. Notably, at 1500 degrees C, the spinel content dramatically surged to 62%. The relationship between spinel content and spent catalyst crystallite size is not linear, the smaller crystal size is more conducive to the dispersion of catalytic active sites, thereby improving the CDM performance. Catalysts without spinel doping exhibited a crystallite size of around 32.2 nm, which decreased to 25.6 nm with 11% spinel content, and increased to 42.7 nm with 62% content. These findings yield profound insights into the influence of calcination temperature and iron cobalt ratios on catalyst performance, providing valuable guidance for the production of efficient CDM catalysts.

The dehydrogenation of formic acid can provide an efficient pathway for hydrogen generation in the presence of a suitable catalyst. Homogeneous catalysts have been extensively studied and utilized for highly active and selective processes compared to conventional heterogeneous catalysis, which often shows lower reactivity and selectivity. However, the latter is preferred for practical applications, considering its easy separation and recyclability. By incorporating a homogeneous organometallic complex on an appropriate support, the unique features of both catalysts can be combined and utilized effectively. Herein, we investigate the immobilization of an iridium picolinamide complex (1) supported on 3D fibrous modified silica that demonstrates high accessibility. The support involves a tetracoordinate aluminum hydride site featuring a strong Lewis acidic nature. A study of the interaction and coordination sites around the surface fragment was conducted via various techniques, including elemental analysis, FT-IR, solid-state NMR, XAS, and first-principles calculations, which provided informative data. We explored the use of solid additives in a solvent-free reaction medium and avoided utilizing volatile bases to achieve process feasibility with a high TOF of 40 000 h-1.

The shale gas revolution has shifted propylene production from naphtha cracking to on-purpose production with propane dehydrogenation (PDH) as the dominant technology1-9. Because PDH is endothermic and requires high temperatures that favour sintering and coking, the challenge is to develop active and stable catalysts1-3 that are sufficiently stable10,11. Zeolite-supported Pt-Sn catalysts have been developed to balance activity, selectivity and stability12,13 and more recent work documented a PDH catalyst based on zeolite-anchored single rhodium atoms with exceptional performance and stability14. Here we show for silicalite-1 (S-1) that migration of encapsulated Pt-Sn2 clusters and hence agglomeration and anchoring within the zeolite versus agglomeration on the external surface can be controlled by adjusting the length of the S-1 crystals' b-axis. We find that, when this axis is longer than 2.00 μm, migration of Pt-Sn2 monomers during PDH results in intracrystalline formation of (Pt-Sn2)2 dimers that are securely locked in the channels of S-1 and capable of converting pure propane feed to propylene at 550 °C for more than 6 months with 98.3% selectivity at 91% equilibrium conversion. This performance exceeds that of other Pt-based PDH catalysts and approaches that of the Rh-based catalyst. Although synthesis requirements and cost are at present prohibitive for industrial use, we anticipate that our approach to controlling the migration and lockup of metals in zeolites may enable the development of other noble-metal catalysts that offer extended service lifetimes in industrial applications15-17.

Formic acid (FA) has been well recognized as one of the most promising hydrogen carriers. The dehydrogenation of the FA could offer an efficient process to on-demand hydrogen generation with a suitable catalyst. Homogeneous catalysts have demonstrated superior activity and selectivity compared to traditional heterogeneous catalysis. However, the latter is preferred for large-scale applications. By incorporating the homogeneous organometallic complex onto an appropriate support, the unique features of both types of catalysts can be combined and utilized effectively. Herein, we synthesized an immobilized PN3P-Ir pincer catalyst (2) supported onto KCC-1, a 3D fibrous silica nanosphere that exhibits a high surface area and contains a tetracoordinate aluminum site. To reduce the use of volatile additives, the choice of cesium formate (CsO2CH) was found to be crucial as at 80-90 degrees C, CsO2CH could act as a reaction medium and serve as basic additive. Remarkable reactivities under neat conditions were achieved with a TOF of 13,290 h-1 and a TON of up to 540,000. The comparative study indicates a significant improvement of 2 from its homogenous counterpart, PN3P-IrH3 (1).

Polytetrafluoroethylene (PTFE) membranes are renowned for their excellent thermal stability, resistance to strong acids and alkalis, and superior mechanical stability. However, its inherent strong hydrophobicity significantly limits its use in water treatment. In this study, a SiO2 coating was successfully deposited in-situ on the surface of PTFE membranes using a hydrolyzed solution of tetraethyl orthosilicate (TEOS) compounded with the commercial fluorinated polyoxyethylene ether surfactant FS-31 (C6F13CH2CH2O(CH2CH2O)nH). The modification mechanism involves using the low surface energy nonionic fluorocarbon surfactant FS-31, which interacts hydrophobically with the PTFE substrate, serving as an "anchor" point around which the TEOS hydrolyzes and condenses around the fibers and nodes of the PTFE membrane, forming a complete and stable chemical network structure. The results show that the initial water contact angle of the modified membrane dropped to 36.5 degrees, and the water flux reached 537.9 L m- 2 h-1. After being continuously immersed in strong acid (5 wt% HCl), strong alkali (4 wt% NaOH), and oxidizing agent (5 wt% NaClO) for one week, the membrane maintained excellent hydrophilicity and stability. This study proposes a mild and efficient modification method to prepare durable hydrophilic PTFE membranes, portending great potential for applications in harsh environments.

The catalytic decomposition of methane (CDM) is a plausible means to convert methane to turquoise hydrogen with simultaneous carbon sequestration, in the form of solid carbon nanomaterials (CNMs). The key to a cost-effective CDM process is a high-performance and low-cost catalysts. Mg-Fe-O CDM catalysts have shown outstanding CDM performance in comparison with Fe, whilst being affordable and easy to produce. By optimizing the Fe: Mg ratios (3: 1, 2: 1, 1: 1, 1: 2, 1: 3) of Mg-Fe-O catalysts to render the best activation and exsolution behavior of fresh catalysts containing partial solid solutions. The structural–functional relationships relevant to CDM are established by characterizing the fresh catalysts, the spent catalysts, as well as catalysts sampled at various stages of CDM by using BET, XRD, TEM-EDS, H2-TPR, Raman and TG. The results are interpreted with the help of computationally calculated phase diagrams of the Mg-Fe-O system at the operating conditions of interest. Notably, the catalyst with a Fe: Mg ratio of 1 offers the optimal CDM performance in terms of methane conversion (maximum 48%) and carbon yield (8.6 gC/gFe), attributed to the efficient exsolution of well dispersed Fe0 particles from the MgO-FeO solid solution matrix. As the CDM reaction proceeded, Fe/MgO catalysts gradually become coated with deposited CNMs, ultimately leading to the CDM process cessation. The results exemplify the importance of understanding the redox behavior of solid solutions for designing cost-effective CDM catalysts with superior catalytic performance.

The synthesis of heterogeneous Ti(iv)-based catalysts for ethylene polymerization following surface organometallic chemistry concepts is described. The unique feature of this catalyst arises from the silica support, KCC-1700. It has (i) a 3D fibrous morphology that is essential to improve the diffusion of the reactants, and (ii) an aluminum-bound hydroxyl group, [(0000000000000000000000000000000000000000000000000000111111111111111000000000000000000011111111111111100000000000000000001111111111111110000000000000000000000000000000000000000000000000000Si-O-Si)(Si-O-)2Al-OH] 2, used as an anchoring site. The [(Si-O-Si)(Si-O-)(Al-O-)TiNp3] 3 catalyst was obtained by reacting 2 with a tetrakis-(neopentyl) titanium TiNp4. The structure of 3 was fully characterized by FT-IR, advanced solid-state NMR spectroscopy [1H, 13C], elemental and gas-phase analysis (ICP-OES and CHNS analysis), and XPS. The benefits of combining these morphological (3D structure) and electronic properties of the support (aluminum plus titanium) were evidenced in ethylene polymerization. The results show a remarkable enhancement in the catalytic performance with the formation of HDPE. Notably, the resulting HDPE displays a molecular weight of 3 200 000 g mol-1 associated with a polydispersity index (PD) of 2.3. Moreover, the effect of the mesostructure (2D vs. 3D) was demonstrated in the catalytic activity for ethylene polymerization. The synthesis of heterogeneous Ti(iv)-based catalysts for ethylene polymerization following surface organometallic chemistry concepts is described.

Nonprecious-metal heterogeneous catalysts with atomically dispersed active sites demonstrated high activity and selectivity in different reactions, and the rational design and large-scale preparation of such catalysts are of great interest but remain a huge challenge. Current approaches usually involve extremely high-temperature and tedious procedures. Here, we demonstrated a straightforward and scalable preparation strategy. In two simple steps, the atomically dispersed Ni electrocatalyst can be synthesized in a tens grams scale with quantitative yield under mild conditions, and the active Ni sites were produced by immobilizing preorganized NiNx complex on the substrate surface via organic thermal reactions. This catalyst exhibits excellent catalysis performances in both oxygen evolution and reduction reactions. It also exhibited tunable catalysis activity, high catalysis reproducibility, and high stability. The atomically dispersed NiNx sites are tolerant at high Ni concentration, as the random reactions and metal nanoparticle formation that generally occurred at high temperatures were avoided. This strategy illustrated a practical and green method for the industrial manufacture of nonprecious-metal single-site catalysts with a predictable structure.

Ammonia is one of the most commonly produced chemicals in the industry. As a result, similar to 1-2% of the world's electrical energy is used, and it produces similar to 1.5-2% of global CO2 emissions. Therefore, developing efficient catalysts at milder conditions is highly desirable. Here, efficient iron/cobalt catalysts for ammonia synthesis are prepared with different Fe/Co ratios from phthalocyanine precursors, resulting in Fe-Co bimetallic nanoparticles embedded in a porous carbon-nitrogen matrix. The incorporation of Co to the Fe catalyst up to 20% wt of Co leads to similar to 40% enhancement in the activity compared to the monometallic Fe-based catalyst. Interestingly, catalysts exhibit excellent activity even at low temperatures (350 degrees C). Ea for the most efficient 6K-FePc80CoPc20 catalyst is found to be 29 kJ.mol(-1), suggesting facile activation of N-2 at low temperatures. An in-depth kinetic study revealed that introducing Co in the Fe catalysts drastically tuned the surface of the catalyst by weakening the various NHx retarding species. Density functional theory calculations confirm the thermodynamic feasibility for introducing 25% of Co at surface Fe sites. This indicates that the presence of Co on the surface draws negative charges from neighboring Fe sites, making the exposed Fe sites neutral and more favorable for N-2 activation on the bimetallic K2O/Co-Fe catalyst and displaying a more thermodynamically feasible energy profile as compared to the pristine K2O/Fe catalyst.

Bimetallic clusters anchored on thermally stable and high-surface-area supports have gained a wide range of applications in heterogeneous catalysis. Compared to monometallic clusters or large bimetallic nanoparticles, bimetallic clusters show unprece-dented catalytic performances due to the modulated electronic and geometric effects arising from the high fraction of surface unsaturated-coordinated metallic atoms and the synergistic effects between two constituting metals. However, even after more than 60 years of efforts, the controlled synthesis of homogeneously distributed bimetallic clusters with well-alloyed structure between two constituting metals remains a tremendous challenge so far. Herein, we present a versatile strategy based on the surface organometallic chemistry concept for synthesizing supported bimetallic cluster catalysts, which is achieved via the hydrogenation of a so-called "double surface organometallic complex ". The cooperative decomposition of two surface organometallic fragments in the double surface organometallic complex and their strong interaction with the support enable the formation of well-alloyed bimetallic clusters uniformly dispersed at the surfaces of different supports. This approach can serve as a platform technique for producing a variety of bimetallic clusters with varied compositions on a wide range of supports, such as Al2O3, TiO2, and zeolite. The resulting bimetallic cluster catalysts exhibit remarkably enhanced catalytic performance in benzene hydrogenation as compared to their monometallic counterparts because of highly exposed surface atoms and synergistic effects between constituting metals.

Surface organometallic chemistry (SOMC) has mainly been devoted to the reaction of organometallics with surfaces comprising highly divided and dehydroxylated oxides. The field has been extended to SOMC on metal nanoparticles. However, to the best of our knowledge, SOMC has not been extended to hierarchical fibrous zeolites, although zeolitic materials are a particular class of oxides. Zeolite catalysis is important in hydrocarbon industrial chemistry. However, having an optimum balance between the activity and selectivity of the zeolitic catalysts remains a major challenge in the field. The main difficultly is the plethora of surface sites, only some of which are catalytically active. Given that the acido-basic properties and porosity of zeolites are especially important to the refining and petrochemical industries, we decided to explore this rather unexplored area. Here, three novel well-defined single-site materials [(Np)3M@ZSM-5, M = Ti, Zr, and Hf] supported on a hierarchical mesoporous H-ZSM-5 material (1) are reported. They are prepared using the concepts and tools of SOMC. They are further converted to their corresponding metal hydride [(H)nM@ZSM-5, M = Ti, Zr, and Hf, (n = 1-2)] materials (5-7) through controlled hydrogenolysis of [(?Si-O-)M(Np)3, M = Ti, Zr, and Hf] materials (2-4) under H2 (1 atm) at 150 degrees C for 16 h. All these surface catalysts are characterized by various spectroscopic techniques including Fourier transform infrared spectroscopy, elemental analysis, solid-state NMR spectroscopy, powder X-ray diffraction, Brunauer-Emmett-Teller surface area measurements, and scanning electron microscopy and high-resolution transmission electron microscopy analyses and are supported by density functional theory calculations. The catalytic activity of these well-defined single-site novel materials will be tested for the catalytic applications in petrochemistry for refinery processes such as hydrocracking of distillates from crude oil or intermediate refinery process streams to useful petroleum value-added products for the society.

Propane dehydrogenation (PDH) over Pt catalyst operated in a moving-bed mode is becoming the dominant process for the on-purpose production of propylene worldwide1-3. Sintering and coking deactivations of Pt catalysts, which greatly decrease the durability and efficiency of this scarce and costly noble metal, are the most challenging issues for the sustainable development of the PDH process4. Even after over half a century of efforts, the development of long-term durable Pt catalysts that are feasible for more economic and efficient fixed-bed operation remains as a formidable task5-10. Herein we report a strategy to modulate the migration-agglomeration-lockup of Pt particles in zeolite silicalite-1 (S-1) for synthesizing highly sintering- and coking-resistant (Pt-Sn2)2@S-1 PDH catalysts. It is found that the migration of Pt-Sn2 clusters in S-1 crystals during the PDH reaction leads to a competition between intra-crystalline agglomeration and external-surface agglomeration of Pt-Sn2 clusters. We show that, when the b-axis length of S-1 crystals is longer than 2 μm, the intra-crystalline agglomeration becomes dominant over the external-surface agglomeration, resulting in the formation of ultra-stable (Pt-Sn2)2@S-1 in which the (Pt-Sn2)2 dimers are securely locked in the channels of S-1 crystals. The long-term durability (4500 hours or about 6 months on stream without perceptible deactivation tendency) of (Pt-Sn2)2@S-1 is at least three orders of magnitude higher than that of the best catalyst reported, which is expected to bring about a breakthrough in revolutionizing the moving-bed operation of the current PDH process to fixed-bed operation. We anticipate that modulating metal migration-agglomeration-lockup within zeolite can act as a general strategy for the synthesis of durable noble metal catalysts, which is beneficial to greatly maximizing the service lifetime of noble metals in industry application11-15.

Abstract Nonprecious-metal catalysts with atomically dispersed active sites demonstrated high activity and selectivity in a series of catalysis reactions, the rational design and massive synthesis of such catalysts are of great interest but remains a huge challenge. Current approaches often require harsh conditions and tedious procedures. Here, we demonstrated a facile and scalable preparation strategy by anchoring pre-organized NiNx site on the surface of a layered Co-methylimidazole coordination compound. In two simple steps, single-site Ni electro-catalyst can be synthesized up to kilogram-scale with a yield of 75% under mild conditions. This catalyst exhibits excellent catalysis performances in both oxygen evolution and reduction reactions. Besides, it has tunable catalysis activity, high catalysis reproducibility and stability. The atomically dispersed NiNx sites are tolerate with high Ni concentration, indicating that the random reactions or metal nanoparticle formation generally observed at high temperature were avoided. This strategy presents a practical and green method for the industrial manufacture of nonprecious-metal single-site catalysts with predictable structure.

Ultrathin covalent organic framework (COF) nanosheets are very appealing 2D materials, but the mass production of ultrathin COF nanosheets remains a great challenge. Here, by using cage-like bicyclocalix[2]arene[2]triazines tri-aldehyde (BCTAL) as the building block, 2D COF Cage-COF-1 was estimated to have a very weak interaction between adjacent layers (around 1/50 compared to that of graphite). As a result, 1.2 nm thick trilayer COF nanosheets were facilely exfoliated from the pristine COFs with large lateral size and high thickness homogeneity. The Cage-COF-1 nanosheet is featured by imine linkage, but it is catalytic inactive in oxygen evolution reaction (OER). After post-metalation with Co2+ under ambient conditions, remarkable catalysis activity and stability was observed for Cage-COF-1-Ns/Co, which has lower overpotential (330 mV) and Tafel slope (56 mV/dec) in catalytic OER compared to many other Co catalysts. This work has confirmed that weakening the interlaminar interaction is an effective strategy for the production of ultra-thin COFs nanosheets. Due to the fully exposed and accessible imine linkage, catalysis active metal site can be controllably produced via post-synthesis from nanosheets under very mild conditions.