Catalytic Reaction Research Articles

ZnIn2S4 nanosheets with geometric defects for enhanced solar-driven hydrogen evolution and wastewater treatment

The key to development of high-performance and low cost photocatalysts hydrogen evolution and waste degradation is to realize efficient photo-generated charge carrier separation and surface catalytic reaction simultaneously without noble metal co-catalyst. To achieve this goal, a noble metal free ZnIn2S4 photocatalyst with geometric defects has been constructed, in which [In-S]4 tetrahedral vacancies (named as (InS)v) on the surface are created by removing the In and S atoms. Further mechanistic investigation has revealed that the (InS)v not only works as the active sites for reductive reaction, but also improves photo-generated electron-hole separation. As a result, the solar-driven hydrogen evolution rate reaches 10.70 mmol/gh without co-catalyst after optimizing the densities of the (InS)v. The apparent quantum efficiency at 380 nm, 395 nm, 420 nm, 450 nm and 520 nm is as high as 14.0 %, 17.1 %, 12.1 %, 8.2 % and 2.4 %, respectively. In addition, these photocatalysts also achieve a rate of 97.78 % and 91.27 % of RhB and MO within 3 and 60 min, respectively. This work show-case a novel approach to develop dual functional and noble metal free photocatalysts for efficiently utilizing solar energy for hydrogen generation and wastewater treatment.

Aggregation-induced emissive copper nanoclusters with peroxidase-like activity for colorimetric detection of cholesterol

Accurate and point-of-care cholesterol detection is of paramount significance for the prevention of cardiovascular diseases. The colorimetric assay based on peroxidase is a commonly used approach for cholesterol detection, without requiring any complicated biomolecular labeling or sophisticated instrumentation. Copper nanoclusters (CuNCs), exhibiting luminescent properties and peroxidase activity, have garnered significant attention in biomedical application recently. Herein, the glutathione-stabilized copper nanoclusters (GSH-CuNCs) were prepared with an easy one-pot method, employing glutathione as both a reducing agent and stabilizer. An optimization of the GSH-CuNCs preparation was carried out to obtain the highest peroxidase-like activity. UV-Vis absorption was measured to explore the steady-state kinetics of the GSH-CuNCs-catalyzed oxidation of 3,3',5,5' - tetramethylbenzidine (TMB) by H2O2. A colorimetric method for cholesterol detection was developed by combining the catalytic reaction of CuNCs and the enzymatic oxidation of cholesterol with cholesterol oxidase (ChOx). Under the optimized conditions, the UV-Vis absorbance of oxidized TMB (oxTMB) is proportional to the concentration of cholesterol within the range of 6.2-187.5 μM, and the limit of detection (LOD) is determined to be 3.0 μM. More importantly, cholesterol levels can be directly distinguished with the naked eye. Furthermore, the practicality of the method for detecting cholesterol in human serum has been verified with promising results. As expected, this simple, cost-effective, and easy-to-operate colorimetric method for cholesterol detection has potential applications in clinical diagnosis and provides valuable insights into the colorimetric sensing based on CuNCs.

Boosting Dry Reforming of Methane Over NiCo/CeO2 Catalysts Treated by Hydrogen Plasma

ABSTRACTNickel (Ni)‐based catalysts are prospective materials for dry reforming of methane (DRM) reaction, but suffer from coke formation and limited activity for CO2 conversion. To improve the reactivity of Ni‐based catalysts, a promising strategy is introducing cobalt (Co) metal. Here, we construct highly efficient NiCo sites on CeO2 support by H2 plasma, which enables the catalyst to obtain a remarkable increase in DRM reaction than the samples treated by conventional H2 reduction. H2 plasma treatment results in the formation of highly dispersed NiCo alloy nanoparticles and high‐concentration oxygen vacancy. These features create large numbers of highly active sites to boost the activation of CH4 and especially CO2 and their catalytic reactions, resulting in strong coke resistance in the DRM reaction.

Synergistic Interaction of Strongly Polar Zinc Selenide and Highly Conductive Carbon Nanoframeworks Accelerates Redox Kinetics of Polysulfides.

Lithium-sulfur batteries (LSBs) have become strong competitors in secondary battery systems because of their superior theoretical capacity and energy density. However, due to the serious shuttle effect of soluble long-chain lithium polysulfides (LiPSs) and the slow solid-solid reaction kinetics, LSBs face some specific challenges, such as a short cycle life and low rate performance. The introduction of selenide/carbon composites derived from zeolite imidazolate frameworks (ZIFs) into separator coatings is a direct and effective solution to the aforementioned problems. Here, a zinc selenide/carbon catalyst material (ZnSe@C) was constructed and employed to modify commercial polypropylene (PP) separators to accelerate the conversion of intermediates. The highly polar ZnSe effectively fixes the active material on the cathode side by transferring electrons between elements with LiPSs and improves the utilization rate of sulfur. Concurrently, the highly conductive carbon nanoskeleton generated following the pyrolysis of ZIF-8 ensures the rapid transfer of charges during the catalytic reaction. The prepared ZnSe@C has a large specific surface area (250.07 m2 g-1) and mesoporous ratio (78.03%), which not only enhances adsorption and catalysis but also promotes the penetration of the electrolyte and the transport of Li+. Based on this, ZnSe@C/PP separator cells exhibit a low average capacity decay rate of 0.051% per cycle after 500 cycles at 1 C.

Atomic‐Level Synergistic Catalysts: Single‐Atom Site Integrated with Atom, Cluster and Nanoparticle

AbstractThe emerging atomic‐level synergistic catalysts based on the single‐atom sites and other valuable components, such as atom, cluster, nanoparticle and other nano‐matter, shine in various catalytic fields. They can integrate the advantages of individual catalytic sites and other valuable components to enhance the activity, selectivity and stability of many chemical reactions via activating their key rate‐determining steps and multistep transformations. In addition, because of the ultrahigh atom utilization (~100 %) and adjustable microenvironment of metal centers, the single‐atom sites can intelligently construct with other useful large size sites to strengthening in tandem a typical catalytic process. Herein, the structure and mechanism of atomic‐level synergistic catalysts with controllable electronic structures and regulatory reaction processes are presented. We particularly emphasize the interactions between active components of atomic‐level synergistic catalysts and catalytic reaction processes, which are essential for understanding how these catalysts are cooperatively working. It is anticipated that this minireview can make the promotion of advanced atomic‐level synergistic catalysts based on single‐atom sites.

Impact of Temperature on Reaction Rate in Catalytic Reactions

Purpose: The aim of the study was to assess the impact of temperature on reaction rate in catalytic reactions. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study indicated that as higher temperatures generally increase the rate at which reactions occur. This is due to the fact that elevated temperatures provide the reactant molecules with more kinetic energy, enabling them to collide more frequently and with greater force, which is necessary to overcome the activation energy barrier. In catalytic reactions, temperature not only accelerates the intrinsic rate of the reaction but can also affect the activity and selectivity of the catalyst. However, too high a temperature can lead to catalyst deactivation through processes such as sintering or coke formation, where the catalyst surface is altered or blocked. Thus, an optimal temperature range is crucial to balance enhanced reaction rates while maintaining catalyst integrity and performance. Implications to Theory, Practice and Policy: Arrhenius equation, transition state theory and collision theory may be used to anchor future studies on the impact of temperature on reaction rate in catalytic reactions. In practical applications, industries should implement advanced temperature control systems to maintain optimal reaction conditions during catalytic processes. Policymakers have a critical role in shaping the landscape of catalytic reactions by developing regulatory guidelines focused on temperature management.

NiII, PdII and PtII pincer complexes of 2-(diphenylphosphanyl)-N-(2-(diphenyl-phosphanyl)benzyl)benzamide: synthesis, reactivity and catalytic studies.

In this article, the synthesis of bis(phosphine), o-Ph2PC6H4C(O)N(H)CH2C6H4PPh2-o (1) (hereafter referred to as "PCNHCP" and its anionic form as "PCNCP") and its group 10 metal chemistry and catalytic studies are described. PCNHCP (1) on reaction with NiCl2(DME) and PdCl2(COD) afforded pincer complexes, [MCl{(PCNCP)κ3-P,N,P}] (M = Ni, 2; Pd, 3). A similar reaction of 1 with PtCl2(COD) yielded a chelate complex, [PtCl2{(PCNHCP)κ2-P,P}] (4), which on further treatment with LiHMDS produced the 1,2-azaphospholene-phosphine complex, [PtCl(Ph){(o-P(Ph)C6H4CONCH2C6H4PPh2-o)κ2-P,P}] (5) via P-C/P-N bond metathesis. Passing dry HCl gas through the solution of 5 resulted in benzene elimination to form [PtCl2{(o-P(Ph)C6H4CONCH2C6H4PPh2-o)κ2-P,P}] (6). Treatment of 1 with PtCl2(COD) and Pt(Cl)(Me)(COD) in the presence of a base resulted in pincer complexes [PtX{(PCNCP)κ3-P,N,P}] (X = Cl, 7; Me, 8). Nickel complex 2 catalyzed the Suzuki-Miyaura cross coupling reaction between bromobenzene and phenyl boronic acid to give the corresponding biphenyls in good yield. The platinum complex 5 showed good catalytic activity towards regio- and stereoselective hydroboration of terminal alkynes. Both the catalytic reactions were performed under mild reaction conditions with a very low catalyst loading.

Intermolecular Gold‐Catalyzed Nitrene Transfer Employing Aryl Azides: An Access to 7‐Functionalized 2‐Aminoindoles

AbstractWe report on intermolecular gold‐catalyzed nitrene transfer, utilizing o‐functionalized aryl azides as nitrene transfer reagents. This catalytic reaction provides a modular route to 7‐functionalized 2‐aminoindoles. Due to the optimized reaction conditions (toluene, 80–100 °C), a variety of functional substituents proved compatible (36 examples; yields up to 98%). The reaction can be performed using both homogeneous and heterogeneous catalytic variants with a low catalyst loading (1 mol %). The synthetic potential of the obtained products was illustrated by post‐modifications of the indole backbone and peripheral substituents. A plausible reaction mechanism includes the generation of intermediate α‐imino carbenes directly from the o‐functionalized aryl azides or other nitrene sources, such as anthranils or benzofuroxans, which form during the reaction in the cases of the specific aryls.

Synthesis of 6- or 8-Carboxamido Derivatives of Imidazo[1,2-a]pyridines via a Heterogeneous Catalytic Aminocarbonylation Reaction.

Imidazo[1,2-a]pyridines and especially their amide derivatives exhibit a wide range of favourable pharmacological properties. In this work, Pd-catalysed carbonylation was used for the first time for the introduction of the carboxamide moiety into positions 6 or 8. A recyclable Pd catalyst, with palladium immobilised on a supported ionic liquid phase decorated with pyridinium ions, was used efficiently for the conversion of 6- or 8-iodo derivatives to the products. In the case of 6-iodo derivatives, a competing mono- and double carbonylation could be observed in the reactions of aliphatic amines as nucleophiles, but under the proper choice of reaction conditions, good-to-excellent selectivities could be achieved towards either the corresponding amides or α-ketomides. The heterogeneous catalyst showed excellent recyclability and low Pd-leaching.

Research on Catalytic Pyrolysis Process of Coconut Coat of Tropical Agricultural and Forestry Wastes

The effects of reaction temperature, reaction time, heating rate, nitrogen flow rate, and catalyst quality on the oil yield and oxygen content in oil were investigated by using the single-factor principle. Too high and too low reaction temperature, nitrogen flow rate, heating rate, and reaction time improved the yield of bio-oil, but the oxygen content in bio-oil was higher. The reduction in catalytic dose is beneficial to the increase in oil yield but not conducive to the increase in aromatic compound content. The optimal reaction conditions were observed as a reaction temperature of 500 °C, a nitrogen flow rate of 110 mL/min, a heating rate of 20 °C/min, a reaction time of 15 min, a mass ratio of catalyst to coconut coat powder of 1, an oil yield of 4.97%, a water yield of 35.80%, and a solid yield of 30.78%. The gas yield was 28.45%, the oxygen content was 10.3%, and the aromatic compound content was 89.7%. The analysis of the catalytic cracking mechanism shows that most of the oxygen-containing compounds in bio-oil are generated into water and aromatic compounds by a catalytic cracking reaction at high temperature, thus removing oxygen.

Efficient and Ultrastable Seawater Electrolysis at Industrial Current Density with Strong Metal-Support Interaction and Dual Cl--Repelling Layers.

Direct seawater electrolysis is emerging as a promising renewable energy technology for large-scale hydrogen generation. The development of Os-Ni4Mo/MoO2 micropillar arrays with strong metal-support interaction (MSI) as a bifunctional electrocatalyst for seawater electrolysis is reported. The micropillar structure enhances electron and mass transfer, extending catalytic reaction steps and improving seawater electrolysis efficiency. Theoretical and experimental studies demonstrate that the strong MSI between Os and Ni4Mo/MoO2 optimizes the surface electronic structure of the catalyst, reducing the reaction barrier and thereby improving catalytic activity. Importantly, for the first time, a dual Cl- repelling layer is constructed by electrostatic force to safeguard active sites against Cl- attack during seawater oxidation. This includes a strong Os─Cl adsorption and an in situ-formed MoO4 2- layer. As a result, the Os-Ni4Mo/MoO2 catalyst exhibits an ultralow overpotential of 113 and 336mV to reach 500mA cm-2 for HER and OER in natural seawater from the South China Sea (without purification, with 1m KOH added). Notably, it demonstrates superior stability, degrading only 0.37 µV h-1 after 2500 h of seawater oxidation, significantly surpassing the technical target of 1.0 µV h-1 set by the United States Department of Energy.

Mechanistic Study of Highly Active Bifunctional Double-Atom Electrocatalysts for Oxygen Reduction and Oxygen Evolution Reactions.

Dual-atom catalysts (DACs) can be very effective for catalyzing both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, we present theoretical evidence of a new class of highly active DACs, namely, the double-atom embedded in nitrogen-doped graphene sheet 2M-N-C (M = Mn, Fe) on the basis of density functional theory calculations. Importantly, we find that the double active sites of 2M-N-C DACs entail an unconventional catalytic reaction pathway for ORR and OER. We also show that the local coordination environment of the active sites can significantly affect the stability and oxygen catalytic activity of 2M-N-C DACs. In particular, MnFe-N-C DAC not only exhibits good stability but also possesses outstanding bifunctional ORR/OER catalytic activity with the potential difference (ΔE) between the OER and ORR as low as 0.34 V, notably lower than most bifunctional electrocatalysts reported in the literature. This finding suggests a new strategy toward the design of stable and highly active bifunctional electrocatalysts for both ORR/OER.

A Comprehensive Investigation on Catalytic Behavior of Anaerobic Jar Gassing Systems and Design of an Enhanced Cultivation System

The rapid and reliable diagnosis of anaerobic bacteria constitutes one of the key procedures in clinical microbiology. Automatic jar gassing systems are commonly used laboratory instruments for this purpose. The most critical factors affecting the cultivation performance of these systems are the level of residual oxygen remaining in the anaerobic jar and the reaction rate determined by the Pd/Al2O3 catalyst. The main objective of the presented study is to design and manufacture an enhanced jar gassing system equipped with an extremum seeking-based estimation algorithm that combines real-time data and a reaction model of the Pd/Al2O3 catalyst. The microkinetic behavior of the palladium catalyst was modeled through a learning-from-experiment methodology. The majority of microkinetic model parameters were derived from material characterization analysis. A comparative validation test of the designed cultivation system was conducted using conventional gas pouches via six different bacterial strains. The results demonstrated high cell viability, with colony counts ranging from 1.26 × 105 to 2.17 × 105 CFU mL−1. The favorable catalyst facets for water formation on Pd surfaces and the crystal structure of Pd/Al2O3 pellets were identified by X-ray diffraction analysis (XRD). The doping ratio of the noble metal (Pd) and the support material (Al2O3) was validated via energy-dispersive spectroscopy (EDS) measurements as 0.68% and 99.32%, respectively. The porous structure of the catalyst was also analyzed by scanning electron microscopy (SEM). During the reference clinical trial, the estimation algorithm was terminated after 878 iterations, having reached its predetermined termination value. The measured and modelled reaction rates were found to converge with a root-mean-squared error (RMSE) of less than 10−4, and the Arrhenius parameters of ongoing catalytic reaction were obtained. Additionally, our research offers a comprehensive analysis of anaerobic jar gassing systems from an engineering perspective, providing novel insights that are absent from the existing literature.

Mechanism of TMB Discoloration Catalyzed by Layered CoNi@CN Nanozymes: Application Based on Smart Phone for Resorcinol Detection

Comprehensive SummaryReal‐time on‐site monitoring of resorcinol (RS) concentrations is crucial for detecting hazardous levels, enabling prompt response measures to mitigate potential environmental and health risks. In this study, we developed an innovative method using CoNi@CN‐2 nanozymes to activate peroxymonosulfate (PMS) for oxidizing 3,3',5,5'‐tetramethylbenzidine (TMB). Our results show that the formation of Ni2+ through the oxidation of Ni0 on the CoNi@CN‐2 surface significantly enhances the electron‐donating capacity of Co0. The catalytic reaction of TMB is mediated by redox active species (SO4•−, •O2−, •OH and 1O2). RS drives colorimetry by transferring electrons to the benzene ring and specific nitrogen atoms in ox‐TMB, reducing ox‐TMB to TMB. Furthermore, the colorimetric assay shows a robust linear correlation between RS concentration and absorbance (Abs), described by Abs = –0.44[RS] + 0.886 (0—200 μmol/L, R2 = 0.983). Also, we introduce a novel smartphone‐integrated autonomous detection software that can analyze RS concentration and grayscale values (GSV), yielding GSV = 0.327[RS] + 63.601 (0—200 μmol/L, R2 = 0.990) with a detection limit of 5.29 μmol/L. Additionally, excess PMS leads to ROS attacking specific sites in ox‐TMB, forming secondary oxidation products. This study has enabled rapid and accurate detection of RS, making a significant contribution to environmental safety and protection.

Design rules for catalysis in single-particle plasmonic nanogap reactors with precisely aligned molecular monolayers

Plasmonic nanostructures can both drive and interrogate light-driven catalytic reactions. Sensitive detection of reaction pathways is achieved by confining optical fields near the active surface. However, effective control of the reaction kinetics remains a challenge to utilize nanostructure constructs as efficient chemical reactors. Here we present a nanoreactor construct exhibiting high catalytic and optical efficiencies, based on a nanoparticle-on-mirror (NPoM) platform. We observe and track pathways of the Pd-catalysed C-C coupling reaction of molecules within a set of nanogaps presenting different chemical surfaces. Atomic monolayer coatings of Pd on the different Au facets enable tuning of the reaction kinetics of surface-bound molecules. Systematic analysis shows the catalytic efficiency of NPoM-based nanoreactors greatly improves on platforms based on aggregated nanoparticles. More importantly, we show Pd monolayers on the nanoparticle or on the mirror play significantly different roles in the surface reaction kinetics. Our data provides clear evidence for catalytic dependencies on molecular configuration in well-defined nanostructures. Such nanoreactor constructs therefore yield clearer design rules for plasmonic catalysis.

Organic Photoredox-Catalyzed Hydrosilylation of Vinylboronic Esters for the Synthesis of Geminal and Vicinal Borosilanes.

Geminal and vicinal borosilanes have unique applications in functional materials and synthetic transformations. Herein, a convenient method for the synthesis of geminal and vicinal borosilanes is developed via photoredox metal-free hydrosilylation of vinylboronic esters. This strategy features the advantages of high atom economy, environmental friendliness, and excellent functional group compatibility. The mechanism studies reveal that the catalytic reaction goes through photoredox HAT catalysis and a radical addition pathway.

Hydrogen Evolution Catalysis by Cobalt Complexes of an Aza‐Bridged Bis‐1,10‐Phenanthroline Ligand Bearing Pendant Basic Sites

AbstractA novel series of molecular Co(II) complexes with aza‐bridged bis‐1,10‐phenanthroline (bpa) ligands have been synthesized and reported for the catalytic hydrogen evolution reaction (HER). Various nitrogen donor substituents are introduced at the aza‐bridge of the bis‐phenanthroline moieties render intramolecular basic sites in the complexes’ second‐coordination sphere. Modifying the pendant nitrogen donor significantly influences the catalytic HER performance. Among these, the cobalt complex with the (2‐pyridyl)methyl substituted bis‐phenanthroline ligand (L3) exhibits the most photocatalytic HER efficiency in both organic and aqueous media. Under optimized conditions with [Ru(bpy)3]2+ as a sensitizer and ascorbic acid as an electron donor, [CoII(L3)(TfO−)2] achieves an initial turnover frequency (TOF) of 1882±65 h−1 per catalyst and a turnover number (TON) of 4842±122 in a 3 hour reaction period under the irradiation of visible light. Combined experimental and theoretical evidences illustrate that phenanthroline moieties of the bpa ligands act as electron mediators during the HER catalysis, while the pendant nitrogen donor substituents mediate proton transfer. This work provides a unique example for understanding the activity‐structure relationship of homogeneous HER catalyst concerning the redox‐active properties and second coordination sphere basic sites of organic ligand platforms.

Atomically Dispersed Vanadium-Induced Ru-V Dual Active Sites Enable Exceptional Performance for Acidic Water Oxidation.

Regulating the catalytic reaction pathway to essentially break the activity/stability trade-off that limits RuO2 and thus achieves exceptional stability and activity for the acidic oxygen evolution reaction (OER) is important yet challenging. Herein, we propose a novel strategy of incorporating atomically dispersed V species, including O-bridged V dimers and V single atoms, into RuO2 lattices to trigger direct O-O radical coupling to release O2 without the generation of *OOH intermediates. Vn-RuO2 showed high activity with a low overpotential of 227 mV at 10 mA cm-2 and outstanding stability during a 1050 h test in acidic electrolyte. Operando spectroscopic studies and theoretical calculations revealed that compared with the V single atom-doping case, the introduction of the V dimer into RuO2 further decreases the Ru-V atomic distance and weakens the adsorption strength of the *O intermediate to the active V site, which supports the more energetically favorable oxygen radical coupling mechanism (OCM). Furthermore, the highly asymmetric Ru-O-V local structure stabilizes the surface Ru active center by lowering the valence state and increasing the resistance against overoxidation, which result in outstanding stability. This study provides insight into ways of increasing the intrinsic catalytic activity and stability of RuO2 by atomically dispersed species modification.

Characterization of Iminobismuthanes and Catalytic Reduction of Organic Azides via Bi(I)/Bi(III) Redox Cycling.

We report the stoichiometric and catalytic reactivity of organobismuth(I) complexes with organic azides. Treatment of N,C,N-pincer bismuthinidenes with organic azides (acyl, sulfonyl, and bulky aryl) results in isolable monomeric iminobismuthanes which can be structurally characterized-including the formal Bi=N double bond-by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. Building upon the stoichiometric reactivity of the monomeric iminobismuthanes, catalytic reduction of a broad range of organic azides is developed. DFT calculations of the catalytic reaction pathway support the redox nature of the overall process.

Atomically Dispersed Vanadium‐Induced Ru‐V Dual Active Sites Enable Exceptional Performance for Acidic Water Oxidation

AbstractRegulating the catalytic reaction pathway to essentially break the activity/stability trade‐off that limits RuO2 and thus achieves exceptional stability and activity for the acidic oxygen evolution reaction (OER) is important yet challenging. Herein, we propose a novel strategy of incorporating atomically dispersed V species, including O‐bridged V dimers and V single atoms, into RuO2 lattices to trigger direct O−O radical coupling to release O2 without the generation of *OOH intermediates. Vn−RuO2 showed high activity with a low overpotential of 227 mV at 10 mA cm−2 and outstanding stability during a 1050 h test in acidic electrolyte. Operando spectroscopic studies and theoretical calculations revealed that compared with the V single atom‐doping case, the introduction of the V dimer into RuO2 further decreases the Ru‐V atomic distance and weakens the adsorption strength of the *O intermediate to the active V site, which supports the more energetically favorable oxygen radical coupling mechanism (OCM). Furthermore, the highly asymmetric Ru−O−V local structure stabilizes the surface Ru active center by lowering the valence state and increasing the resistance against overoxidation, which result in outstanding stability. This study provides insight into ways of increasing the intrinsic catalytic activity and stability of RuO2 by atomically dispersed species modification.