Metal Support Research Articles

Fabrication of ridged microstructures on FeCrAl porous metal support enhanced catalyst coating performance by UV-laser micromilling

Fabrication of ridged microstructures on FeCrAl porous metal support enhanced catalyst coating performance by UV-laser micromilling

Bimetallic NiCo Nanoparticles Embedded in Organic Group Functionalized Mesoporous Silica for Efficient Hydrogen Production from Ammonia Borane Hydrolysis

In this study, bimetallic NiCo nanoparticles (NPs) were encapsulated within the mesopores of carboxylic acid functionalized mesoporous silica (CMS) through the chemical reduction approach. Both NaBH4 and NH3BH3 were used as reducing agents to reduce the metal ions simultaneously. The resulting composite was used as a catalyst for hydrolysis of ammonia borane (NH3BH3, AB) to produce H2. The bimetallic NiCo NPs supported on carboxylic group functionalized mesoporous silica, referred to as NixCo100−x@CMS, exhibited significantly higher catalytic activity for AB hydrolysis compared to their monometallic counterparts. The remarkable activity of NixCo100−x@CMS could be ascribed to the synergistic contributions of Ni and Co, redox reaction during the hydrolysis, and the fine-tuned electronic structure. The catalytic performance of the NixCo100−x@CMS nanocatalyst was observed to be dependent on the composition of Ni and Co. Among all the compositions investigated, Ni40Co60@CMS demonstrated the highest catalytic activity, with a turn over frequency (TOF) of 18.95 molH2min−1molcatalyst−1 and H2 production rate of 8.0 L min−1g−1. The activity of Ni40Co60@CMS was approximately three times greater than that of Ni@CMS and about two times that of Co@CMS. The superior activity of Ni40Co60@CMS was attributed to its finely-tuned electronic structure, resulting from the electron transfer of Ni to Co. Furthermore, the nanocatalyst exhibited excellent durability, as the carboxylate group in the support provided a strong metal–support interaction, securely anchoring the NPs within the mesopores, preventing both agglomeration and leakage.

Synergistic Electronic Interaction in PdCu Alloy/TiO2-NSs for Ambient Efficient Dehydrogenation of Formic Acid.

Palladium-based catalysts are remarkable in endorsing hydrogen (H2) generation through formic acid (HCOOH, FA) dehydrogenation under near-ambient conditions. Hydrogen energy efficiency depends on high-performance catalyst design. In this study, Pd-Cu nanoalloy catalysts with mutable atomic ratios are successfully fabricated on TiO2 nanosheets (TiO2-NSs).The synergistic electronic interactions between Palladium (Pd) and copper (Cu) are revealed through a density of states (DOS) analysis of alloy supported over a mixed valence state of Ti linked to oxygen vacancies (Vo) in TiO2-NSs, Enhanced adsorption of target molecules reveals novel active sites for Formic acid dehydrogenation (FAD), with O─H bond cleavage via HCOO formate intermediate preceding C─H and C─O bond cleavage. Experimental and theoretical research demonstrates that the Pd-Cu/TiO2-NSs (3:7) catalyst d electron redistribution and d-band center shift lower the activation energy for O─H bond cleavage, exhibit superior H2 production than pure Pd and Cu, increasing Pd electron density due to synergistic effects from reactive crystal facets, defects, and strong metal support interactions (SMSI), lowering the activation energy for HCOOH dissociation step, generating carbon dioxide (CO2) and H2 with a unprecedented high turnover frequency (TOF) of 6268 molH2.h-1.molPd-1 at 303K with activation energy (Ea) of 15 KJ mol-1. This attempt models an efficient HCOOH-to-hydrogen catalyst.

Diffusive ex situ galvanic growth of metal nanocrystals on transmission electron microscopy grid

The uniform modification of commercial and standardized objects features considerable potential, as in the case of dip-pen lithography, biosensor kits, and disposable electrodes. In this study, we devised a dense nanoparticle array formation using the metallic mesh of a transmission electron microscopy (TEM) grid, which was formerly solely employed as a sampling stage. Incompletely oxidized cationic species generated from the galvanic replacement reaction of the metallic support mesh at the opposite side of the carbon layer diffused to the exposed top side and led to ex situ nanostar formation. A uniform nanoparticle array was obtained by immersion in an aqueous solution of replacing metal cations without reducing agents or surface energy-controlling compounds. Moreover, the array density was exclusively regulated by the incubation time. The straightforward nanoparticle array formation was successfully extended to various metal mesh TEM grids and different transition metal cations capable of spontaneous redox reactions. Cu mesh TEM grid and Mo grids could be utilized as sacrificial templates, and the growth of Au, Pd, Pt, Ag, and Rh nanostructures was confirmed.

Strong Metal–Support Interaction Induces Dual Reaction Sites for Ultrasensitive and Stable NO2 Detection in Extreme Environments

AbstractThe tripartite combination of a high density and stability of surface reaction sites, complemented by the longevity and efficient transfer of interface carriers, along with the effective adsorption and activation of target gas molecules, jointly determines the efficiency of chemiresistors. In this work, the strong metal–support interaction (SMSI) of Pt─Ce3+ is formed by the NaBH4 reduction method and thus prepares metal‐dynamically stable PtNR─CeO2 with Pt─Ce3+ and Pt─Pt reaction sites. The formation of SMSI induces the recombination of the chemical structure of the CeO2 surface causing the localization of electron‐rich Ce3+, which greatly increases the charge concentration at the interface. The experimental findings of the strong interaction of Pt─Ce3+ bonding and the catalytic effect of Pt optimized the adsorption mode of PtNR─CeO2 on target gas, which maintains stable catalytic activity at 20–500 °C and achieving a notable detection response value of 1.43 for 20 ppb NO2. This work offers fresh insights into designing stable oxide chemiresistors with efficiency and stability by customizing reaction sites at the atomic level.

High Oxygen Reduction Efficiency and Durability of Nano-Honeycomb Pt3(NiFeCo) Replenished by High-Entropy Metallic Glass Support.

Developing low-Pt oxygen reduction reaction (ORR) catalysts with high efficiency and robustness is critical for practical fuel cells. The most advanced ORR catalysts either feature high percentages of Pt (>70 at.%) or exhibit poor durability when reducing Pt loading. Herein, a multicomponent solid-solution Pt3(FeCoNi) honeycomb nano-framework supported by the specially designed high-entropy metallic glass (MG) is reported for efficient ORR. This hybrid catalyst with a low surface Pt loading of 5.79µgcm-2 displays exceptional mass and specific activities of 7.02Amgpt -1 and 8.15mAcmPt -2 at 0.9V, respectively, which are ≈15 and 22 times higher compared with commercial Pt/C. The analyses reveal the weakened chemisorption of oxygenated species, which is induced by the strong strain and ligand effects originating from the synergistic multicomponent alloying. This in turn enhances the intrinsic ORR activity. Moreover, benefiting from a unique replenishment behavior, the hybrid catalyst delivers ultra-high durability with negligible activity decay even after 50 000 potential cycles. This mechanism is achieved by sacrificing the interior MG supplementary support to dynamically compensate for the loss of catalytically active surface. The work provides an alternative way to design more efficient and durable low-Pt electrocatalysts for electrochemical devices.

Electronic Structure Engineering of Single-Atom Tungsten on Vacancy-enriched V3S4 Nanosheets for Efficient Hydrogen Evolution.

Constructing single-atom catalysts (SACs) and optimizing the electronic structure between metal atoms and support interactions is deemed one of the most effective strategies for boosting the catalytic kinetics of the hydrogen evolution reaction (HER). Herein, a sulfur vacancy defect trapping strategy is developed to anchor tungsten single atoms onto ultrathin V3S4 nanosheets with a high loading of 25.1wt.%. The obtained W-V3S4 catalyst exhibits a low overpotential of 54mV at 10mA cm-2 and excellent long-term stability in alkaline electrolytes. Density functional theory calculations reveal that the in situ anchoring of W single atoms triggers the delocalization and redistribution of electron density, which effectively accelerates water dissociation and facilitates hydrogen adsorption/desorption, thus enhancing HER activity. This work provides valuable insights into understanding highly active single-atom catalysts for large-scale hydrogen production.

Understanding the Environmental Sensitivity of Copper‐Metal Oxides Interactions in Cu/ZnO and Cu/Al2O3 Catalysts

AbstractTernary Cu/ZnO/Al2O3 catalysts are one of the most important industrial catalysts and show excellent activity in methanol reforming reaction. However, it is challenging to elucidate the metal support interactions, which critically influence the catalyst structure and performance, due to their environmentally sensitive nature. This study examines the interactions between Cu and Al2O3 and ZnO, after reductive treatments of the Cu/Al2O3 and Cu/ZnO model catalysts with varying temperatures and hydrogen concentration. A combination of Brunner‐Emmet‐Teller (BET) measurements, X‐ray diffraction (XRD), N2O titration, diffuse reflectance infrared Fourier transformations spectroscopy (DRIFTS) and high‐resolution transmission electron microscopy (HRTEM) provided comprehensive insights into the structural evolution of the catalysts.

Immobilization of carbon composite materials on structured frameworks for application in continuous catalytic experiments: Application in NO3- conversion

Bimetallic catalysts applied for water treatment are highly susceptible to deactivation/poisoning mainly when immobilized in macroscopic structures. Metal support interaction characteristic of metal oxides/composite supports emerges as an important strategy for controlling this phenomenon.This work explores a novel washcoating methodology to synthesize macrostructured composite catalysts for selective nitrate reduction. This approach allowed to effectively integrate powder composite materials into macroscopic frameworks, allowing to take advantage of modifications performed in the powder materials, often associated with increased catalytic activity/selectivity.Pd-Cu composite materials (metal oxides with carbon nanotubes) were prepared/tested for nitrate conversion. Titanium dioxide composites achieved the best performance (54 % nitrate conversion and 61 % N2 selectivity), outperforming the results obtained with more conventional synthesis methodologies. The catalysts proved to be highly active and resistant over several hours of reaction. This is a pioneering work focused on the synthesis and application of macrostructured composite catalysts in G-L-S (gas-liquid-solid) treatment systems.

Graphene-Based Catalysts: Emerging Applications and Potential Impact.

Carbon nanofillers in general and graphene in particular are considered as promising potential candidates in catalysis due to their two-dimensional (2D) nature, zero bandwidth, single atom thickness with a promising high surface area: volume ratio. Additionally, graphene oxide via result of tunable electrical properties has also been developed as a catalytic support for metal and metal oxide nanofillers. Moreover, the possession of higher chemical stability followed by ultrahigh thermal conductivity plays a prominent role in promoting higher reinforcement of catalytically active sites. In this review we have started with an overview of carbon nanofillers as catalyst support, their main characteristics and applications for their use in heterogeneous catalysis. The review article also critically focusses on the catalytic properties originating from both functional groups as well as doping. An in-depth literature on the various reaction catalysed by metal oxide based nanoparticles supported on GO/rGO has also been incorporated with a special focus on the overall catalytic efficiency with respect to graphene contribution. The future research prospective in the aforementioned field has also been discussed.

Computational screening of Group VⅢ@C5N4 single-atom electrocatalysts for overall water splitting

Single-atom catalysts (SACs) have great potential for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) since their high atomic utilization and strong metal–support interactions. Herein, we develop TM@C5N4 (TM = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt) catalysts via embedding Group VⅢ TM in holey C5N4 substrate and further evaluate their electrocatalytic activity using density functional theory (DFT) calculations. Systematical studies indicate that Fe@C5N4, Pd@C5N4 and Ir@C5N4 catalysts all exhibit excellent HER performance, which mainly because of their small ΔGH* values of 0.101 eV, -0.114 eV and 0.070 eV, respectively. In parallel, Rh@C5N4 and Ir@C5N4 possess high OER activity along with low overpotential of 0.50 V, which is superior to the commercial IrO2 catalyst (0.56 V). Obviously, Ir@C5N4 could be utilized as bifunctional electrocatalysts both HER and OER in water splitting. Furthermore, we analyze their correlative catalytic mechanisms using the molecular orbitals. Besides, biaxial strain modulation could effectively regulate the catalytic activity of HER and OER. Particularly, 2 % biaxial tensile strain could bring Ir@C5N4 superb HER/OER catalytic performance. Finally, we anticipate that this strain engineering would provide a new perspective for developing high-performance SACs for water splitting.

Metal–Support Interaction between Pd Oxide and YCoO3 Effective for NO Reduction with CO and C3H6

Metal–Support Interaction between Pd Oxide and YCoO₃ Effective for NO Reduction with CO and C₃H₆

In-situ carbon integration on atomically dispersed platinum metal oxide nanocomposites for hydrogen evolution reaction

In this study, a novel in-situ carbon growth technique by a modified sol gel synthesis method is presented. The carbon support developed on a transition metal oxide composite transforms the electronic conductivity and is engineered for hydrogen evolution reaction by a dispersion of unit atomic concentration of platinum. Through two different synthesis techniques, platinum dispersion is implemented on the metal oxide-carbon system, one by direct sol-gel technique and another by chemical reduction technique, whereby a homogeneous dispersion of the noble metal on the composite is achieved. Carbon-based cerium oxide and titanium oxide composites are used as the base material, and one atomic percentage of platinum metal is ensured while synthesizing each of the carbon composites. The functionality of these catalysts towards hydrogen evolution reaction in a 0.5 M H2SO4 acidic media revealed the synthesis technique's uniqueness and the effect of metal support interaction that plays a vital role in the electrocatalytic activity. The intrinsic activity of the titania system, along with enhanced metal support interaction due to highly enriched platinum availability on the surface of the substrate, provides for strong electrochemical activity. The titanium oxide carbon composite with platinum dispersed by hydrazine reduction exhibited the finest activity with an overpotential of just 44 mV at j = 10 mA/cm2 and a tafel slope of 118 mV/dec. The gas chromatographic analysis on platinum supported titania catalyst showcased better performance by a margin of four times than the commercial three weight percentage platinum supported carbon.

Advancing greener LNG-fueled vessels: Compact simultaneous reduction system for CH4, NOX and CO2 emissions

Stringent ship regulations necessitate simultaneous emission reductions, challenged by cargo loss and energy constraints. This study proposes a compact reduction system that simultaneously mitigate CH4, NOX, and CO2 emissions onboard LNG-fueled vessels. The proposed system integrates two pivotal technologies: a metal support-based compact methane oxidation catalyst (MOC)-selective catalytic reduction (SCR) system to capture CH4 and NOX, and a cryogenic CO2 capture (CCC) system to capture and store CO2 in its solid phase utilizing LNG's cold energy. This innovative approach addresses two challenges. First, the compact MOC-SCR system employs metal support with an enhanced surface area-to-volume ratio surpassing the capabilities of ceramic support materials, achieving a volume reduction of 80.02% and 79.82% respectively. Secondly, the CCC system significantly lowers specific energy consumption by 61.54% by harnessing LNG's cold energy compared to the absorption-based CO2 capture system. As a result, the proposed system not only reduces CH4, NOX, and CO2 emissions simultaneously with a high capture rate but also reduces volume and weight. Furthermore, it achieves a high CO2 capture rate of 92.12%, while diminishing cargo losses by 25.30%. These findings provide valuable guidance for developing environmentally sustainable vessels, aligning with the continuously increasing stringency of regulations.

Powder bed fusion of solid and permeable Crofer 22 APU parts for applications in chemical process engineering

AbstractAdditive manufacturing of metals has attracted significant attention across various industries. However, its adoption in certain chemical and energy sectors remains constrained by the absence of optimized alloys tailored for high temperatures and corrosive environments. This study explores the laser-based powder bed fusion processing of Crofer 22 APU, a high-temperature, corrosion-resistant alloy ideal for applications such as methane steam reforming reactors, high-temperature fuel cells, and palladium membrane supports. Systematic optimization of laser parameters including laser power, hatch distance, point distance, and building angles was conducted for both dense and porous objects. Dense parts achieved a relative density of 0.9999 and surface roughness of Sa= 41.27±1.48 on a 45$$^\circ$$ ∘ overhang. Porous samples showed a porosity range of 28.655.5% and surface roughness Sa 22.2 $$\upmu$$ μ m to 45.9 $$\upmu$$ μ m as hatch distance increased from 0.12 mm to 0.16 mm. Additionally, an 8YSZ coating applied via screen printing demonstrated the impact of hatch distance and laser power on surface quality. The combination of additive manufacturing of Crofer 22 APU and screen printing of 8YSZ simplifies the preparation of metallic supports for Pd-based membranes, reducing fabrication time and cost by shortening the number of preparation steps. This technique offers a promising approach for scaling up membranes and membrane reactors.

Non-Classical Deactivation Mechanism in a Supported Intermetallic Catalyst for Propane Dehydrogenation.

Platinum-based supported intermetallic alloys (IMAs) demonstrate exceptional performance in catalytic propane dehydrogenation (PDH) primarily because of their remarkable resistance to coke formation. However, these IMAs still encounter a significant hurdle in the form of catalyst deactivation. Understanding the complex deactivation mechanism of supported IMAs, which goes beyond conventional coke deposition, requires meticulous microscopic structural elucidation. In this study, we unravel a nonclassical deactivation mechanism over a PtZn/γ-Al2O3 PDH catalyst, dictated by the PtZn to Pt3Zn nanophase transformation accompanied with dezincification. The physical origin lies in the metal support interaction (MSI) that enables strong chemical bonding between hydroxyl groups on the support and Zn sites on the PtZn phase to selectively remove Zn species followed by the reconstruction towards Pt3Zn phase. Building on these insights, we have devised a solution to circumvent the deactivation by passivating the MSI through surface modification of γ-Al2O3 support. By exchanging protons of hydroxyl groups with potassium ions (K) on the γ-Al2O3 support, such a strategy significantly minimizes the dezincification of PtZn IMA via diminished metal-support bonding, which dramatically reduces the deactivation rate from 0.2044 to 0.0587 h-1. These findings decode the nonclassical PDH deactivation mechanism over supported IMA catalysts and elaborate a new logic for the design of high-performance IMA based PDH catalysts with long-term stability.

Investigating the efficacy of Palladium Doped Ceria for the Photodegradation of Azo Dyes

Ceria (CeO2) was prepared by microwave assisted precipitation method while sonothermal method was utilized for the synthesis of palladium doped ceria (Pd-CeO2) photocatalyst. HR-TEM analysis confirms the face centered cubic geometry (FCC) of CeO2. The particle size of Pd-CeO2 calculated from HR-TEM analysis (7.6±2.18 nm) is in close relation with XRD (8.25±0.25 nm). The SAED pattern of Pd-CeO2 shows the poly crystallinity where the d-spacing was 0.31 and 0.30 nm which corresponds to CeO2 and Pd crystal facets 111 and 100 respectively. The amount of dopant and existence of Pd, Ce and O was confirmed from EDX spectra and elemental mapping. BET surface area analysis of CeO2 (64.45 m2/g), Pd-CeO2 (60.20 m²/g) revealed that the decrease in the surface area of CeO2 due to Pd loading which is confirmed by pore volume (0.079 cm³/g) for CeO2 and pore volume for Pd-CeO2 (0.073 cm³/g). The photocatalytic activity of Pd-CeO2 was screened against a model azo dye Acid red-4 (AR-4). The fluctuation of the rate of photodegradation (PD) of AR-4 was observed under different reaction conditions. Therefore, the reaction parameters were optimized to achieve best catalytic activity up to PD; 98%. The kinetic study suggests that the PD of AR-4 follows 1st order kinetics with regression coefficient (R2=0.973) and rate constant (k=0.024/min). Recycling study revealed the prolong use of catalyst without significant loss of activity. DFT study and experiments revealed the synergism of Pd on the photo response of CeO2. Perhaps this synergistic effect due to metal support interaction, causes redistribution of charges and Fermi energy levels. The synthesized catalyst showed potential application for the treatment of textile industrial effluents.

Facile synthesis of multifunctional zeolitic imidazolate framework-8 coatings on diverse bare substrates using a one-step strategy

Rational growth of metal–organic frameworks (MOFs) with controllable morphology and surface properties has been challenging. In this study, facile synthesis of zeolitic imidazolate framework-8 (ZIF-8) in solutions as well as direct in-situ growth of ZIF-8 on various untreated substrates was studied systematically. ZIF crystals with controllable morphology and size were prepared by simply adjusting the ethanol content in the co-solvent system, achieving a rational synthesis of ZIFs in controlled environments. More importantly, co-solvent content was proved to be crucial in the inter-dimensional topotactic phase transformation from a 2-dimensional ZIF-L to a three-dimensional ZIF-8. Then, the facile in-situ crystallization of ZIF-8 on a variety of untreated substrates was studied. With the use of co-solvents, ZIF-8 crystals were formed uniformly and continuously on all substrates regardless of the nature of the support material, including organic supports such as nylon membranes, 3D printed meshes, melamine sponges, mask filter layers, fabric, metallic support stainless-steel meshes, and ceramic pellet. This facile coating strategy provided controllable crystal coating morphology, size, and coating density, without surface modification/pre-treatment steps which are commonly used in the synthesis of high-quality ZIF coatings/membranes. The ZIF-8 coated substrates prepared in a co-solvent system displayed superior performance in some environmental remediation and biomedical applications. For example, the ZIF-8-coated nylon membrane achieved an impressive 96 ∼ 98 % small oil droplet removal from emulsions while maintaining a high water flux of ∼ 1200 L m−2h−1 bar−1. The superhydrophobic ZIF-8-coated melamine sponges were effective for fast oil adsorption. Last but not least, the ZIF-8-coated masks demonstrated greatly improved antibacterial activities. Overall, the co-solvent synthesis method reported in this work has enabled a one-step universal strategy for the direct growth of zeolitic imidazolate framework coating on diverse bare substrates with controlled surface properties and thus showed significant commercial potential in environmental and biological applications.

Electronic Metal‐Support Interaction Induces Hydrogen Spillover and Platinum Utilization in Hydrogen Evolution Reaction

The substantial promotion of hydrogen evolution reaction (HER) catalytic performance relies on the breakup of the Sabatier principle, which can be achieved by the alternation of the support and electronic metal support interaction (EMSI) is noticed. Due to the utilization of tungsten disulfides as support for platinum (Pt@WS2), surprisingly, Pt@WS2 demands only 31 mV overpotential to attain 10 mA cm‐2 in acidic HER test, corresponding to a 2.5‐fold higher mass activity than benchmarked Pt/C. The pH dependent electrochemical measurements associated with H2‐TPD and in‐situ Raman spectroscopy indicate a hydrogen spillover involved HER mechanism is confirmed. The WS2 support triggers a higher hydrogen binding strength for Pt leading to the increment in hydrogen concentration at Pt sites proved by upshifted d band center as well as lower Gibbs free energy of hydrogen, favourable for hydrogen spillover. Besides, the WS2 shows a comparably lower effect on Gibbs free energy for different Pt layers (‐0.50 eV layer‐1) than carbon black (‐0.88 eV layer‐1) contributing to a better Pt utilization. Also, the theoretical calculation suggests the hydrogen spillover occurs on the 3rd Pt layer in Pt@WS2; moreover, the energy barrier is lowered with increment in hydrogen coverage on Pt.

Electronic Metal-Support Interaction Induces Hydrogen Spillover and Platinum Utilization in Hydrogen Evolution Reaction.

The substantial promotion of hydrogen evolution reaction (HER) catalytic performance relies on the breakup of the Sabatier principle, which can be achieved by the alternation of the support and electronic metal support interaction (EMSI) is noticed. Due to the utilization of tungsten disulfides as support for platinum (Pt@WS2), surprisingly, Pt@WS2 demands only 31 mV overpotential to attain 10 mA cm-2 in acidic HER test, corresponding to a 2.5-fold higher mass activity than benchmarked Pt/C. The pH dependent electrochemical measurements associated with H2-TPD and in-situ Raman spectroscopy indicate a hydrogen spillover involved HER mechanism is confirmed. The WS2 support triggers a higher hydrogen binding strength for Pt leading to the increment in hydrogen concentration at Pt sites proved by upshifted d band center as well as lower Gibbs free energy of hydrogen, favourable for hydrogen spillover. Besides, the WS2 shows a comparably lower effect on Gibbs free energy for different Pt layers (-0.50 eV layer-1) than carbon black (-0.88 eV layer-1) contributing to a better Pt utilization. Also, the theoretical calculation suggests the hydrogen spillover occurs on the 3rd Pt layer in Pt@WS2; moreover, the energy barrier is lowered with increment in hydrogen coverage on Pt.