Catalytic Performance Research Articles

Fibrillated Films for Suspension Catalyst Immobilization—A Kinetic Study of the Nitrobenzene Hydrogenation

The immobilization of suspension catalysts in flexible, fibrillated films offers a promising solution to the mass transfer limitations often encountered in three-phase hydrogenation reactions. This study investigates the catalytic performance and mass transfer properties of fibrillated films in the hydrogenation of nitrobenzene to aniline, comparing them to free-flowing powdered catalysts. Fibrillated films were prepared from Pd/C catalysts with varying thicknesses (100–400 µm), and their performance was evaluated through kinetic studies in both batch reactors and microreactors. The specific activity of the films was significantly influenced by film thickness with thinner films demonstrating lower mass transfer limitations. However, mass transfer limitations were observed in thicker films, prompting the development of alternative film designs, including enhanced macro-porous films and sandwich structures. These modifications successfully minimized diffusion limitations, achieving similar specific activity to the powder catalysts while maintaining the mechanical stability of the films. This work demonstrates the feasibility of using fibrillated films for continuous catalytic processes and highlights their potential for efficient catalyst reuse, avoiding filtration steps and enhancing process sustainability. Furthermore, while PTFE remains indispensable for producing such films due to its mechanical and thermal stability, ongoing research focuses on identifying more environmentally friendly alternatives without compromising performance.

Alanine Production by Chemical Upcycling of Polylactic Acid Waste Over Fe-Doped Ru/CeO2.

Biodegradable polyesters, such as polylactic acid (PLA), is one of the most promising plastics with great potential to contribute to enabling a sustainable global circular economy. However, the efficient chemical upcycling of PLA plastic waste into high-value chemicals remains a grand challenge. Herein, a series of Ru/CeFeOx catalysts with varying Ru loadings were developed for the catalytic amination of PLA plastic waste to alanine in the presence of ammonia. The as-prepared catalysts exhibited exceptional catalytic activity, high selectivity, and excellent recyclability, achieving an alanine yield of 70.5 % at 180 °C for 18 h, significantly surpassing previous reports. The outstanding catalytic performance can be primarily attributed to the presence of Fe species in Ru/CeFeOx, which generated more oxygen vacancies, provided abundant base sites, and enhanced reducibility, therefore accelerating the reaction rate and enhancing catalytic efficiency. This study presents an alternative strategy for the sustainable chemical upcycling of PLA plastic waste into alanine and the realization of a circular economy.

Discovery of Alloy Catalysts for Ammonia Decomposition by Machine Learning-Based Prediction of Adsorption Energies

Ammonia decomposition has gained significant attention as an eco-friendly method for hydrogen production because it creates no carbon dioxide emissions. While Ru catalysts are known for their high activity in ammonia decomposition, their high cost makes them uneconomical for commercial use. Therefore, it is essential to explore novel alloy catalysts composed of inexpensive elements with high catalytic performance. Nitrogen adsorption energies serve as key descriptors indicating the catalytic performance for ammonia decomposition, and first-principle calculations can compute these energies. However, the screening of numerous alloy catalyst candidates through extensive first-principle calculations and experimental validations remains time-consuming due to the vast number of potential candidates. To address this, artificial intelligence and machine learning models are being developed to quickly predict catalyst performance, efficiently searching for promising catalyst candidates. In this study, we developed a machine-learning-based method to rapidly predict nitrogen adsorption energies using a graph-based artificial neural network, thereby efficiently searching for novel catalysts for ammonia decomposition. Our training dataset included the nitrogen adsorption energies of 30 pure transition metal catalyst candidates, as well as binary alloy catalyst candidates, including core-shell and intermetallic compounds. As a result, we successfully identified 12 catalyst candidates composed of inexpensive elements that are likely to exhibit catalytic performance comparable to Ru catalysts.

Efficient paddle-wheel copper cluster-based metal-organic framework for catalytic conversion of CO2 to oxazolidinones under mild conditions

Efficient utilization of CO2 and its conversion into high-value-added products contribute to mitigating environmental issues such as the greenhouse effect. Among these methods, the carboxylation cyclization of CO2 with propargylic amine represents a green and atom-economical approach. Developing cost-effective catalyst that can promote this reaction under mild condition is desirable but challenging. Herein, a unique two-dimensional (2D) metal–organic framework (MOF) {[Cu(QCA)2]∙0.5DMF∙0.5H2O}n (1) (QCA =6-quinolinecarboxylic acid, DMF = N,N-dimethylformamide) have been synthesized and thoroughly characterized. Compound 1 was constructed from paddle-wheel dinuclear copper clusters [Cu2(COO)4] and carboxylate ligands, presenting a two-dimensional framework with new topology. Stability tests indicate that compound 1 undergoes reversible structural changes in different solvents and exhibits good thermal stability. 1 as heterogeneous catalyst enabled the transformation of CO2 and propargylic amine into oxazolidinones under mild conditions with broad substrate generality. In addition, 1 could maintain its catalytic performance with five continuous reactions. This work presents an infrequent example of a 2D noble metal free MOF-based catalyst that shows high catalytic efficiency under mild conditions.

Roles of Divinylbenzene Co‐Cross‐Linker in a Threefold Cross‐Linked Polystyrene–Phosphine Hybrid Monolith: Impact of Cross‐linking Degree on Catalytic Performance

AbstractContinuous‐flow organic transformations using immobilized catalysts are crucial for green and sustainable chemistry. Cross‐linked polymer ligands offer high stability, ease of recovery through filtration, and thus enhance performance in continuous‐flow reactions via transition‐metal catalysis. Additionally, the cross‐linking structure of the polymer support creates a unique reaction platform that controls the coordination behavior of the supported ligands and stabilizes the metal catalysts. However, insights into the material‐based design for preparing highly active and durable immobilized metal catalysts are still limited. In this report, we propose a straightforward approach to boost both selective mono‐coordination and effective stabilization of metal complexes. We developed threefold cross‐linked polystyrene‐triphenylphosphine hybrid monoliths with cross‐linking structures adjusted by varying the content of divinylbenzene as co‐cross‐linker. The coordination behaviors and metal‐support interactions of these monoliths were evaluated, highlighting the importance of co‐cross‐linker content in site‐isolating phosphine units and stabilizing metal centers via arene‐metal interactions on the polystyrene network. By optimizing the cross‐linking structure, the monolith catalysts demonstrated exceptionally high catalytic activity and durability in Pd‐catalyzed C−Cl transformations, such as Suzuki–Miyaura cross‐couplings and Buchwald‐Hartwig aminations in continuous flow. This underscores the utility of our monolith system in challenging transition‐metal catalysis.

Role of Active Centers in Predicting the Catalyst Turnover: A Theoretical Study.

Water oxidation catalysis has garnered significant attention due to its potential for sustainable energy conversion. Among molecular catalysts, [Fe(OTf)2 (Me2Pytacn)] complexes have exhibited notable turning-over rates. Although various [M(OTf)2 (Me2Pytacn)] complexes (M = Mn, Co, Ni) have been synthesized, however, the role of active centres has not been thoroughly investigated. In this study, we apply our newly developed catalytic models, efficiency conceptualization model (ECM) and the maximum kinetic efficiency MaxKinEff framework to assess the role of the active centres in its catalytic performance. Our computational analysis identifies cobalt-based [Co(OTf)2 (Me2Pytacn)] as a superior alternative for water oxidation reactions. Notably, cobalt catalysts exhibit a longer lifespan (~ 44 days) and higher turnover numbers (TON), with computed values of (ECM) = 3.30 h-1, (ECM) = 3456, (MaxKinEff) = 12.43 h-1, and (MaxKinEff) = 3616. These findings suggest that cobalt could play a pivotal role in improving the efficiency of molecular catalysts for water oxidation.

Cu-Doped V-Based MOF Derivative VO2@Cu-VMOF as a Cathodic Catalyst for Electro-Fenton Degradation of Antibiotics.

In this study, the VO2@5%Cu-VMOF/graphite felt (GF) is prepared as an electro-Fenton cathode via hydrothermal process and low-temperature carbonization for efficient antibiotics degradation. The VO2@5%Cu-VMOF/GF cathode exhibit great ciprofloxacin (CIP) degradation performance over the pH range of 2.1-7.2, and CIP removal reached 98.1% within 60min at a pH of 3.4, with corresponding total organic carbon (TOC) removal of 68.7%. The cathode also showed desired catalytic performance toward various antibiotics decomposition. The great catalytic activity of the VO2@5%Cu-VMOF/GF cathode is attributed to lattice strain induced by Cu doping, and the elimination of the overpotential difference between the optimal oxygen reduction potential (OP ORR) and optimal metal reduction potential (OP MRR). Density Function Theory (DFT) calculations showed that Cu doping facilitated electrons accumulation around V atoms, and thus increased the content of low-valence metals in the cathode material. Four possible degradation pathways for CIP are proposed and intermediate toxicity is evaluated. This work advances the design and application of MOF derivatives as electro-Fenton cathodic materials for emerging contaminants degradation.

Atomic catalysis meets heterostructure synergy: Unveiling the trifunctional efficacy of transition Metal@WS2/ReSe2

Integrating and advancing renewable energy storage and conversion technologies such as water splitting and rechargeable air-based batteries face significant challenges in finding appropriate catalysts that offer both high activity and low cost. This paper successfully designed efficient, cost-effective, and eco-friendly catalysts that meet the requirements for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) catalytic activity by employing two-dimensional (2D) transition metal dichalcogenides (TMDs) interface engineering combined with a single-atom doping strategy. First, the heterostructure was constructed, and its optimal layer spacing (3.13 Å) was determined by calculating the most negative binding energy. These materials were theoretically evaluated using density functional theory (DFT), demonstrating that transition metal (TM) can all be firmly attached to the S1 site of the WS2/ReSe2 Z-scheme heterostructure with favorable binding energies and excellent electronic properties. By comparing the catalysts doped with different metals (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn), the three functional catalysts with the best performance were finally selected: Mn@WS2/ReSe2, Ni@WS2/ReSe2, and Cu@WS2/ReSe2. In particular, Mn@WS2/ReSe2 exhibited exceptional promise as multifunctional catalysts, with overpotentials for the HER/OER/ORR of 0.05/0.29/0.35 V, respectively. The superior catalytic performance of this WS2/ReSe2 Z-scheme heterostructure was attributed to the introduction of TM atoms and the synergistic interaction between rhenium and the TM atoms. This interaction facilitated more efficient electron transfer between the catalyst and the reactants, enhancing the overall catalytic activity. This research is a successful attempt to combine interface engineering with single-atom catalysis (SACs). It provided valuable insights into the design of next-generation multifunctional electrocatalysts, offering a novel approach to address the growing energy demands in an environmentally benign and economically viable way.

Iron-Induced Localized Oxide Path Mechanism Enables Efficient and Stable Water Oxidation.

The sluggish reaction kinetics of the anodic oxygen evolution reaction (OER) and the inadequate catalytic performance of non-noble metal-based electrocatalysts represent substantial barriers to the development of anion exchange membrane water electrolyzer (AEMWE). This study performed the synthesis of a three-dimensional (3D) nanoflower-like electrocatalyst (CFMO) via a simple one-step method. The substitution of Co with Fe in the structure induces a localized oxide path mechanism (LOPM), facilitating direct O-O radical coupling for enhanced O2 evolution. The optimized CFMO-2 electrocatalyst demonstrates superior OER performance, achieving an overpotential of 217 mV at 10 mA cm-2, alongside exceptional long-term stability with minimal degradation after 1000 h of operation in 1.0 M KOH. These properties surpass most of conventional noble metal-based electrocatalysts. Furthermore, the assembled AEMWE system, utilizing CFMO-2, operates with a cell voltage of 1.65 V to deliver 1.0 A cm-2. In situ characterizations reveal that, in addition to the traditional adsorbate evolution mechanism (AEM) at isolated Co sites, a new LOPM occurred around the Fe and Co bimetallic sites. First-principles calculations confirm the LOPM greatly reduced the energy barriers. This work highlights the potential of LOPM for improving the design of non-noble metal-based electrocatalysts and the development of AEMWE.

Pd/UiO‐66(Zr)‐2OH as a High‐Performance Catalyst for Hydrogen‐Enhanced Fenton Oxidation of Trimethoprim

ABSTRACTA novel catalyst material named Pd/UiO‐66(Zr)‐2OH was successfully developed and applied in a hydrogen‐promoted Fenton system for the efficient catalytic oxidation of the widely used antibiotic trimethoprim (TMP). The UiO‐66(Zr)‐2OH, as the carrier of catalyst in this work, was synthesized through a solvothermal method. The Pd0 nanoparticle, as the active center of the catalyst, was loaded onto its surface by the “ship‐in‐a‐bottle” strategy. The results showed that the composite Pd/UiO‐66(Zr)‐2OH demonstrated excellent catalytic performance during the reaction, achieving over 97% of TMP removal efficiency within 180 min under optimal conditions under the condition of only trace of iron without adding H2O2. This may be attributed to the fact that the [H], as a clean and efficient reducing agent, can be utilized to accelerate the regeneration of Fe2+ in the Fenton reaction, as well as in the in‐situ regeneration of H2O2. The key parameters affecting the removal efficiency of TMP, including the initial pH and concentration of Fe2+, the dosage of the synthesized material, the flow rate of H2 and the stirring speed were investigated systematically. The Pd/UiO‐66(Zr)‐2OH exhibited high stability and reusability, maintaining over 82% of its initial degradation efficiency of TMP after six reaction cycles. The mechanistic insight revealed that the system primarily relied on the generation of hydroxyl radical (·OH) and singlet oxygen (1O2) for the degradation of TMP, which was verified through quenching experiments and electron spin resonance (ESR). The degradation pathway of TMP was elucidated by analyzing intermediates and the reduction in total organic carbon (TOC). This research offers novel conceptual insights into the evolution and application of advanced oxidation technologies, efficient degradation of emerging pollutants, and expansion of pathways for hydrogen resource utilization.

Cu- and S-Doped Heteropolyacid Co2Mo10 as Electrocatalysts for Efficient Hydrogen Evolution.

This study employed polyoxometalate Co2Mo10 as a precursor and a two-step method to prepare carbon cloth-supported CuxS-CoS2-MoS2 materials. The morphology and structure of the materials were characterized using XRD, XPS, SEM, TEM, and other techniques. Interestingly, changes in the reducing gas during the calcination process could adjust the product morphology, thereby altering catalytic activity. Electrochemical results indicated that the CuxS-CoS2-MoS2 nanomaterials prepared under an NH3 atmosphere exhibited unique morphology and structural advantages. They demonstrated significant electrocatalytic activity for the hydrogen evolution reaction (HER) in alkaline and acidic electrolytes (overpotentials of 108 and 196 mV at a current density of 10 mA cm-2, lower than the overpotentials of 143 and 226 mV obtained under a H2-Ar atmosphere during calcination) and excellent long-term durability. These findings provide insights and methods for synthesizing multicomponent electrocatalysts with enhanced catalytic performance.

Synthesis of alumina/ferric oxide nanofibers and application to catalysts for ethanol dehydration reaction by adding palladium oxide

AbstractAlumina/ferric oxide (Al₂O₃/Fe₂O₃) composite nanofibers were fabricated via electrospinning followed by heat treatment. Structural characterization revealed mesoporous morphology with high porosity and surface area and uniform dispersion of catalytically active Fe₂O₃ nanoparticles. Catalytic evaluation for ethanol dehydration demonstrated superior performance for nanofibers containing 5 wt% Fe₂O₃, attributed to their unique structural features. Further enhancement was achieved by incorporating palladium oxide (PdO), resulting in improved catalytic activity, particularly in ethylene productivity. Surface acid properties were altered with PdO addition, suggesting a role of Lewis acid sites in augmenting catalytic performance. The developed PdO/Al₂O₃/Fe₂O₃ nanofibers exhibit stable performance over multiple cycles, offering promising prospects for efficient ethanol dehydration catalysts.

Iron‐Induced Localized Oxide Path Mechanism Enables Efficient and Stable Water Oxidation

The sluggish reaction kinetics of the anodic oxygen evolution reaction (OER) and the inadequate catalytic performance of non‐noble metal‐based electrocatalysts represent substantial barriers to the development of anion exchange membrane water electrolyzer (AEMWE). This study performed the synthesis of a three‐dimensional (3D) nanoflower‐like electrocatalyst (CFMO) via a simple one‐step method. The substitution of Co with Fe in the structure induces a localized oxide path mechanism (LOPM), facilitating direct O–O radical coupling for enhanced O2 evolution. The optimized CFMO‐2 electrocatalyst demonstrates superior OER performance, achieving an overpotential of 217 mV at 10 mA cm–2, alongside exceptional long‐term stability with minimal degradation after 1000 h of operation in 1.0 M KOH. These properties surpass most of conventional noble metal‐based electrocatalysts. Furthermore, the assembled AEMWE system, utilizing CFMO‐2, operates with a cell voltage of 1.65 V to deliver 1.0 A cm–2. In situ characterizations reveal that, in addition to the traditional adsorbate evolution mechanism (AEM) at isolated Co sites, a new LOPM occurred around the Fe and Co bimetallic sites. First‐principles calculations confirm the LOPM greatly reduced the energy barriers. This work highlights the potential of LOPM for improving the design of non‐noble metal‐based electrocatalysts and the development of AEMWE.

Comparison of oxygen evolution reaction performance for Ni and Co using isostructural trans‐cinnamate complexes

AbstractEfforts are underway to develop highly active catalysts to reduce the high overpotential of the oxygen evolution reaction (OER). Metal–organic frameworks or coordination polymers are promising candidates because of their tunable structures and high surface areas. In this study, Nickel and Cobalt trans‐cinnamate (t‐ca) were synthesized via a hydrothermal method. Their structures were analyzed and found to be isostructural. Both complexes exhibited superior electrocatalytic properties in the OER compared to those of IrO2, with overpotentials of 373 and 390 mV and Tafel slopes of 58 and 66 mV/dec. These excellent characteristics were attributed to the electron delocalization of the metal centers via interactions with π‐π delocalized organic ligands. Ni t‐ca, with stronger ligand interactions, displayed an enhanced OER catalytic performance, emphasizing the importance of metal–ligand interactions and suggesting that further exploration of diverse π–π delocalized organic ligands and metal centers may lead to further advancements in electrocatalytic activity.

Activation of Persulfate by NiFe-Layered Double Hydroxides Toward Efficient Degradation of Doxycycline in Water

In recent years, the excessive use and improper disposal of antibiotics have led to their pervasive presence in the environment, resulting in significant antibiotic pollution. To address this pressing issue, the present study synthesized nickel–iron-layered double hydroxides (NiFe-LDHs) with varying molar ratios using a hydrothermal method, employing these LDHs as catalysts for the oxidative degradation of doxycycline, with peroxymonosulfate (PMS) serving as the oxidant. X-ray diffraction analysis confirmed that the synthesized NiFe-LDHs exhibited a hexagonal crystal structure characteristic of layered double hydroxides. Experimental results demonstrated that the catalytic efficiency of NiFe-LDHs increased with both the dosage of the catalyst and the concentration of PMS, achieving a high degradation efficiency for doxycycline at a catalyst concentration of 0.5 g/L. Furthermore, the catalytic performance was notably effective across a range of pH conditions, with the highest degradation efficiency being observed at a Ni–Fe molar ratio of 3:1. The activation of PMS by NiFe-LDHs for the catalytic degradation of pollutants primarily occurs through singlet oxygen (1O2), superoxide radicals (O2−·), and sulfate radicals (SO4−·). The study also proposed three potential degradation pathways for doxycycline, indicating that the final degradation products have lower environmental toxicity. This research offers novel approaches and methodologies for the treatment of antibiotic-contaminated wastewater.

Based on magnetically recoverable catalysts: a green strategy to sulfonamides.

The synthesis of sulfonamides, a class of compounds with significant pharmaceutical and medicinal applications, has seen remarkable advancements with the advent of magnetic nanocatalysts. Magnetic nanocomposites are one of the most efficient and widely used catalysts, and they are in complete harmony with the principles of modern green chemistry from the point of view of catalysis. These catalysts, typically composed of metal complexes supported on magnetic nanoparticles, offer unique advantages such as ease of recovery and reusability, which are crucial for sustainable and eco-friendly chemical processes. This review comprehensively examines recent developments in applying magnetic nanocatalysts to prepare sulfonamides. Key focus areas include the design and synthesis of various magnetic nanocatalysts (MNC), their catalytic performance in different reaction conditions, and mechanistic insights into their catalytic activity. By summarizing the latest research and technological advancements, this article aims to provide a valuable resource for researchers and practitioners in catalysis and pharmaceutical chemistry.

Recent Advances in Immobilizing and Benchmarking Molecular Catalysts for Artificial Photosynthesis.

Transition metal complexes have been widely used as catalysts or chromophores in artificial photosynthesis. Traditionally, they are employed in homogeneous settings. Despite their functional versatility and structural tunability, broad industrial applications of these catalysts are impeded by the limitations of homogeneous catalysis such as poor catalyst recyclability, solvent constraints (mostly organic solvents), and catalyst durability. Over the past few decades, researchers have developed various methods for molecular catalyst heterogenization to overcome these limitations. In this review, we summarize recent developments in heterogenization strategies, with a focus on describing methods employed in the heterogenization process and their effects on catalytic performances. Alongside the in-depth discussion of heterogenization strategies, this review aims to provide a concise overview of the key metrics associated with heterogenized systems. We hope this review will aid researchers who are new to this research field in gaining a better understanding.

Catalytic ozone oxidation performance of Fe-Ce@γ-Al2O3 in reverse osmosis concentrate treatment

The reverse osmosis concentrate (ROC) produced in the process of textile wastewater treatment has a high salt content, posing a significant environmental threat. In this study, catalytic ozone oxidation was used to treat ROC, which initially had a chemical oxygen demand (COD) of 127.38 mg/L. The Fe-Ce@γ-Al2O3 catalysts had the best performance under the Fe/Ce doping ratio of 3:1, calcination temperature of 500 °C with calcination time of 4 h. SEM and XRD analyses confirmed the successful loading of Fe and Ce on γ-Al2O3. The catalytic ozone oxidation conditions were optimized by the response surface method (RSM). Under the optimal reaction conditions (catalyst dosage of 139.07 g/L, ozone ventilation rate of 1.65 L/min, and initial pH of 9.86), the actual COD removal rate reached 89.21 %. Three-dimensional fluorescence spectroscopy was used to analyze the degradation mechanism of dissolved organic matter (DOM) during the treatment of ROC. Three-dimensional fluorescence spectrum (3DEEM) results demonstrated the obvious degradation of DOM in ROC after the catalytic ozone oxidation treatment. The COD removal rate remained at approximately 80 % after 10 recycles, indicating that the Fe-Ce@γ-Al2O3 catalyst had good catalytic stability and reusability. In summary, the Fe-Ce@γ-Al2O3 catalysts demonstrate sustained practical effectiveness and high catalytic efficiency, making them suitable for the treatment of ROC.

Exploring Pt-Cu synergistic effects on porous SiO2 support with different Pt loadings for low-temperature oxidation of CO and C3H6

To address the high cost of noble metals, this study aims to optimize Pt loading and the synergistic effect of Cu on porous SiO2 support for low-temperature oxidation of CO and C3H6. A simulated test bench system was used to evaluate the performance of PtxCu1/SiO2 (where x= 0.3, 0.5, 0.7, and 1 wt%), Cu1/SiO2 and Ptx/SiO2 (where x= 0.5 and 1 wt%) catalysts with varying Pt loadings. Comprehensive characterization, including BET, XRD, SEM, TEM, and XPS was conducted to assess particle size, structure, and surface morphology. The effects of Pt incorporation on reduction and oxidation properties were further examined using H2-TPR and CO-TPD techniques. Results demonstrated a significant enhancement in catalytic activity with the addition of Cu confirming a synergistic interaction between Pt and Cu. This synergy was particularly pronounced in lower Pt loadings, where PtxCu1/SiO2 composites outperformed Ptx/SiO2 in catalytic activity. Pt addition reduced the particle size, which resulted in the creation of PtCu alloy, with 1 and 0.7 % wt Pt loading exhibiting comparable effects in CO conversion and 0.7 % Pt loading exhibiting better activity at higher temperatures in C3H6 oxidation indicating that catalytic activity was maintained even with a reduced Pt loading. Additionally, minimal difference in activity for C3H6 oxidation was observed among PtxCu1/SiO2 catalysts with 0.7, 0.5, and 0.3 wt% Pt loadings as indicated by T50 and T80 values. Reducing Pt loading from 0.7 wt% had minimal impact on catalytic efficiency for C3H6 oxidation with catalysts maintaining high activity. 0.7 wt% Pt loadings provide sufficient active sites for effective CO and HC oxidation. The enhanced catalytic activity and stability of bimetallic catalysts over monometallic Cu/SiO2 and Pt/SiO2 result from the simultaneous presence of active sites created by the synergetic effect of PtCu alloy formation with optimal ratio and well-optimized surface. These findings demonstrate the potential to optimize Pt usage without compromising catalytic performance, offering a cost-effective approach to catalyst design.

Engineering a Mesoporous Silicon Nanoparticle Cage to Enhance Performance of a Phosphotriesterase Enzyme for Degradation of VX Nerve Agent.

The organophosphate (OP)-hydrolyzing enzyme phosphotriesterase (PTE, variant L7ep-3a) immobilized within a partially oxidized mesoporous silicon nanoparticle cage is synthesized and the catalytic performance of the enzyme@nanoparticle construct for hydrolysis of a simulant, dimethyl p-nitrophenyl phosphate (DMNP), and the live nerve agent VX is benchmarked against the free enzyme. In a neutral aqueous buffer, the optimized construct shows a ≈2-fold increase in the rate of DMNP turnover relative to the free enzyme. Enzyme@nanoparticles with more hydrophobic surface chemistry in the interior of the pores show lower catalytic activity, suggesting the importance of hydration of the pore interior on performance. The enzyme@nanoparticle construct is readily separated from the neutralized agent; the nanoparticle is found to retain DMNP hydrolysis activity through seven decontamination/recovery cycles. The nanoparticle cage stabilizes the enzyme against thermal denaturing and enzymatic (trypsin) degradation conditions relative to free enzyme. When incorporated into a topical gel formulation, the PTE-loaded nanoparticles show high activity toward the nerve agent VX in an ex vivo rabbit skin model. In vitro acetylcholinesterase (AChE) assays in human blood show that the enzyme@nanoparticle construct decontaminates VX, preserving the biological function of AChE when exposed to an otherwise incapacitating dose.