Enhancement Of Catalytic Activity Research Articles

Enhancing catalytic activity of CO2 electrolysis by building efficient and durable heterostructure for solid oxide electrolysis cell cathode

Solid oxide electrolysis cell (SOEC) has great application prospects in the fields of renewable energy storage, CO2 capture and utilization. One of the key factors hindering the development of SOEC is the lack of suitable cathode materials. In this study, we designed and developed a kind of new micro-nano heterostructure materials Co@Sr1.95Fe1.4Co0.1Mo0.4Ti0.1O6-δ (Co@SFCMT), Co nanoparticles uniformly distributed on the SFCMT matrix and provided rich electric catalytic active sites, SFCMT showed excellent oxygen ion transport performance. The synergistic effect of Co nanoparticles and Sr1.95Fe1.4Co0.1Mo0.4Ti0.1O6-δ (SFCMT) increased the rate of CO2 reduction reaction (CO2RR). At 1.8 V and 800 °C, the maximum electrolytic current density of the cell with Co@SFCMT as the cathode reached 2.57 A cm−2. In addition, Co@SFCMT showed good stability at 1.5 V and 750 °C, with no performance decay even after 200 h of continuous operation. The micro-nano heterostructure design strategy of perovskite oxides will not only open new avenues for designing SOEC electrodes, but also be expected to promote the development of other energy storage and conversion systems.

Mott‐Schottky Heterostructure Photocatalysis of Ag/h‐BN/Bi2O3 for Water Pollutants Degradation

AbstractThe Ag/h‐BN/Bi2O3 ternary composite was facilely fabricated via self‐assembly combined with in situ reduction. Characterization results showed that the as‐prepared Ag/h‐BN/Bi2O3 possessed distinct surface plasma resonance (SPR) and Mott‐Schottky heterostructure, resulting in significant enhancement of catalytic activity for RhB removal, the reaction rate constant (2.26×10−2 min−1) is 2.5 times that of h‐BN/Bi2O3 under visible‐light irradiation for 2 hours, which was mainly ascribed to the SPR and Mott‐Schottky heterostructure result in Ag/h‐BN/Bi2O3 enhanced visible‐light harvesting capacity and the effectual spatial separation of photoinduced carriers. The quenching process of reactive species indicated that h+ and ⋅O2− play dominant role in the degradation for pollutants. This work demonstrates that Ag/h‐BN/Bi2O3 is a promising stability photocatalyst for water purification.

BiPO4/Ag3PO4/Bi2SiO5 heterojunction: controllable synthesis and its enhancement of visible light catalytic activity

BiPO4/Ag3PO4/Bi2SiO5 heterojunction: controllable synthesis and its enhancement of visible light catalytic activity

Homotropic Cooperativity in Iron-Catalyzed Alkyne Cyclotrimerizations.

Enhancing catalytic activity through synergic effects is a current challenge in homogeneous catalysis. In addition to the well-established metal-metal and metal-ligand cooperation, we showcase here an example of self-activation by the substrate in controlling the catalytic activity of the two-coordinate iron complex [Fe(2,6-Xyl2C6H3)2] (1, Xyl = 2,6-Me2C6H3). This behavior was observed for aryl acetylenes in their regioselective cyclotrimerization to 1,2,4-(aryl)-benzenes. Two kinetically distinct regimes are observed dependent upon the substrate-to-catalyst ratio ([RC≡CH]0/[1]0), referred to as the low ([RC≡CH]0/[1]0 < 40) and high ([RC≡CH]0/[1]0 > 40) regimes. Both showed sigmoidal kinetic response, with positive Hill indices of 1.85 and 3.62, respectively, and nonlinear Lineweaver-Burk replots with an upward curvature, which supports positive substrate cooperativity. Moreover, two alkyne molecules participate in the low regime, whereas up to four are involved in the high regime. The second-order rate dependence on 1 indicates that binuclear complexes are the catalytically competent species in both regimes, with that in the high one being 6 times faster than that involved in the low one. Moreover, Eyring plot analyses revealed two different catalytic cycles, with a rate-determining step more endergonic in the low regime than in the high one, but with a more ordered transition state in the high regime than in the low one.

Montmorillonite-supported NiFe2O4 as magnetically separable and reusable oxidation catalyst

By supporting NiFe2O4 onto montmorillonite, the highly active and reusable catalyst for methyl violet oxidation was obtained. By using XRD, TEM, XPS, and VSM analyses, it is obtained that the concentration of precursor was a controlling factor to determine the specific surface area, NiFe2O4 particle size, and magnetism. It is found that adsorption influences the catalytic activity enhancement and the stability of catalysts.

Self-assembly of shell protein and native enzyme in a crowded environment leads to catalytically active phase condensates.

The self-assembly of bacterial microcompartments is the result of several genetic, biochemical, and physical stimuli orchestrating inside the bacterial cell. In this work, we use 1,2-propanediol utilization microcompartments as a paradigm to identify the factors that physically drive the self-assembly of MCP proteins in vitro using its major shell protein and major encapsulated enzyme. We find that a major shell protein PduBB' tends to self-assemble under macromolecular crowded environment and suitable ionic strength. Microscopic visualization and biophysical studies reveal phase separation to be the principle mechanism behind the self-association of shell protein in the presence of salts and macromolecular crowding. The shell protein PduBB' interacts with the enzyme diol-dehydratase PduCDE and co-assemble into phase separated liquid droplets. The co-assembly of PduCDE and PduBB' results in the enhancement of catalytic activity of the enzyme. The shell proteins that make up PduBB' (PduB and PduB') have contrasting self-assembly behavior. While N-terminal truncated PduB' has a high self-associating property and forms solid assemblies that separates out of solution, the longer component of the shell protein PduBM38L is more soluble and shows least tendency to undergo phase separation. A combination of spectroscopic, imaging and biochemical techniques shows the relevance of divalent cation Mg2+ in providing stability to intact PduMCP. Together our results suggest a combination of protein-protein interactions and phase separation guiding the self-assembly of Pdu shell protein and enzyme in the solution phase.

Enzyme Stabilization and Catalytic Activity Enhancement by Single-Chain Nanoparticles of Fluorinated Zwitterionic Random Copolymers

Enzyme Stabilization and Catalytic Activity Enhancement by Single-Chain Nanoparticles of Fluorinated Zwitterionic Random Copolymers

Simultaneous enhancement of thermostability and catalytic activity of κ-carrageenase from Pseudoalteromonas tetraodonis by rational design

κ-Carrageenase provides an attractive enzymatic approach to preparation of κ-carrageenan oligosaccharides. Pseudoalteromonas tetraodonis κ-carrageenase is active at the alkaline conditions but displays low thermostability. To further improve its enzymatic performance, two mutants of Q42V and I51H exhibiting both improved thermostability and enzyme activity were screened by the PoPMuSiC algorithm. Compared with the wild-type κ-carrageenase (WT), Q42V and I51H increased the enzyme activity by 20.9% and 25.4%, respectively. After treatment at 50 ℃ for 40 min, Q42V and I51H enhanced the residual activity by 31.1% and 25.9%, respectively. The Tm values of Q42V, I51H, and WT determined by differential scanning calorimetry were 58.2 ℃, 54.8 ℃, and 51.2 ℃, respectively. Compared with untreated and HCl-treated κ-carrageenans, Q42V-treated κ-carrageenan exhibited higher pancreatic lipase inhibitory activity. Molecular docking analysis indicated that the additional pi-sigma force and hydrophobic interaction in the enzyme-substrate complex could account for the increased catalytic activity of Q42V and I51H, respectively. Molecular dynamics analysis indicated that the improved thermostability of mutants Q42V and I51H could be attributed to the less structural deviation and the flexible changes of enzyme conformation at high temperature. This study provides new insight into κ-carrageenase performance improvement and identifies good candidates for their industrial applications.

Enhancing catalytic activity for toluene and acetone oxidation over ZraCo1-aOx catalysts by doping Zr to improve the oxygen activation capacity due to formation of Zr-O-Co bonds

Transition metal oxides are considered as effective catalysts for eliminating volatile organic compounds (VOCs) due to their superior characteristics of abundant reserves and low price. A series of ZraCo1-aOx composite oxides was synthesized through a facile hydrothermal method and applied for catalytic oxidation of toluene and acetone. The catalytic activity of ZraCo1-aOx is improved by adjusting the elemental content composition, especially the Zr0.4Co0.6Ox sample exhibits the superior catalytic ability for both toluene (T90 = 231 °C) and acetone (T90 = 208 °C) oxidation under WHSV of 40,000 mL·g−1·h−1. The doping of Zr in ZraCo1-aOx induces to form Zr-O-Co bonds and enlarges the specific surface area compare with pure Co3O4, which improves the redox capacity and increase active oxygen content. In situ DRIFTS tests were used to detect reaction intermediates in the toluene and acetone oxidation process on the catalyst surface, and the advantageous function of Zr doping on promoting activation of oxygen was further determined. Furthermore, the outstanding activity stability and water resistance of the Zr0.4Co0.6Ox catalyst facilitate its application in industrial environments. This work provides a theoretical basis for preparing the catalyst to eliminate VOCs in industrial applications.

A bimetallic co-doped iron and copper in polymeric graphitic carbon nitride to enhance catalytic activity and reusability of Fenton-like oxidation

In this study, a new Fenton-like catalyst was developed through incorporating iron and copper in polymeric graphitic carbon nitride (FeCu/CN) for catalytic activity and reusability enhancement. With theoretical Fe/Cu ratio of 7:3 (Fe7Cu3/CN) and pH of 5, the bimetallic catalyst system showed a pseudo-first-order rate constant of 0.07294 min−1 for bisphenol S (BPS) degradation, which was near double the sum of values in monometallic catalyst systems. Moreover, the new catalyst showed much better performance for reuse, BPS removal of which catalyzed system decreased from 98.0 % to 87.3 % after five cycles used. Comparatively, BPS removal declined from 69.5 % to 45.0 % in Fe/CN catalyzed system. Characterization results indicate the superiority of Fe7Cu3/CN for Fenton-like catalysis is mainly attributed to the intrinsic advantage of CN support, Fe(II) formation, copper catalysis, and synergistic effect between iron and copper. Furthermore, hydroxyl radicals were determined as the main species for pollutant degradation, and their accumulation was monitored. The destruction pathways of BPS were analyzed by detection of degradation intermediates, and the results further confirm the main active species of hydroxyl radicals. Moreover, the new Fenton-like system also exhibited good performance for different pollutant removal and real wastewater treatment. This study provided a new catalyst with superior catalytic activity and favorable reusability, and also sheds new light on supported bimetallic catalyst development.

Resultant inward imbalanced seeding force (RIISF)-induced concave gold nanostar (CAuNS) for non-enzymatic electrocatalytic detection of serotonin and Kynurenine in human serum.

CTAC-based gold nanoseed-induced concave curvature evolution of surface boundary planes from concave gold nanocube (CAuNC) to concave gold nanostar (CAuNS) has been achieved by a novel synthetic methodology simply by controlling the extent of seed used and hence the generated 'Resultant Inward Imbalanced Seeding Force (RIISF)'. The resultant CAuNS shows an excellent enhancement in catalytic activity compared to CAuNC and other intermediates as a function of curvature-induced anisotropy. Detailed characterization evaluates the presence of an enhanced number of multiple defect sites, high energy facets, larger surface area, and roughened surface which ultimately results in an increased mechanical strain, coordinately unsaturation, and multifacet-oriented anisotropic behavior suitable for positive influence on the binding affinity of CAuNSs. While different crystalline and structural parameters improve their catalytic activity, the resultant uniform three-dimensional (3D) platform shows comparatively easy pliability and well absorptivity on the glassy carbon electrode surface for increased shelf life, a uniform structure to confine a large extent of stoichiometric systems, and long-term stability under ambient conditions for making this newly developed material a unique nonenzymatic scalable universal electrocatalytic platform. With the help of various electrochemical measurements, the ability of the platform has been established by performing highly specific and sensitive detection of the two most important human bio messengers: Serotonin (STN) and Kynurenine (KYN) which are metabolites of L-Tryptophan in the human body system. The present study mechanistically surveys the role of seed-induced RIISF-modulated anisotropy in controlling the catalytic activity which offers a universal 3D electrocatalytic sensing tenet by an electrocatalytic approach.

Catalytic boosting on AuCu bimetallic nanoparticles by oxygen-induced atomic restructuring

Understanding the structure-activity relationship over silica-supported Au-based bimetallic nanocatalysts in CO oxidation is essential in elucidating active sites and catalytic mechanisms. Here, we uncover that structure-activity relationship over a silica-supported 10 nm sized AuCu bimetallic model nanocatalyst for CO oxidation. Oxygen–induced atomic restructuring of AuCu nanocrystals is comprehensively investigated using combined operando spectroscopic and microscopic techniques, including near-ambient-pressure X-ray photoelectron spectroscopy, diffuse reflectance infrared Fourier-transform spectroscopy, and environmental transmission electron microscopy. We show that the formation of CuOx/Au heterostructure gives rise to the enhancement of catalytic activity for CO oxidation. The formation of the reactive heterostructure on catalysis was rationalized by density functional theory calculation. Our results indicate that intermediate heterostructure with a metal-oxide interface leads to strong electronic coupling between catalyst and support (i.e., electronic metal-support interaction effect).

Ag@Pt等离激元复合纳米结构中热电子级联传输增 强电催化反应

A popular strategy for constructing localized surface plasmon resonance (LSPR)-enhanced plasmonic metal heterostructure catalysts is to fabricate a composite of highly active materials with plasmonic metal nanomaterials. However, this kind of combination not only decreases the LSPR response intensity but also changes the hot electron transport pathway inside the heterogeneous structure, which induces the ineffective transfer of plasmonic hot electrons to the surface of the heterostructures and hinders the effective enhancement of catalytic activity. Herein, simple Ag@Pt bimetallic nanocubes are selected to explore the mechanism of hot electrons from excitation and transmission within a plasmonic metal het-erostructure and their contribution to the electrochemical hydrogen evolution reaction (HER). The corresponding experimental and theoretical results confirm that the hot electrons (holes) become a dominant plasmon decay pathway owing to the introduction of thin Pt shells and HER can be significantly enhanced by hot electrons via a cascaded manner, i.e., first being excited in Ag, then pumped from Ag atoms to Pt atoms and accumulated on the surface of Pt. This work provides an important reference for the design and application of plasmonic metal heterostructure catalysts.

Design and identify the confinement effect of active site position on catalytic performance for selective catalytic reduction of NO with NH3 at low temperature

In heterogeneous catalysis, the migration and aggregation of active nanoparticles has always been a challenging problem in catalyst design. Two types of confined catalysts, including the pore confined Pore-CeW/OMT and framework confined FW-CeW/OMT were successfully designed for NH3-SCR process in this work. Experimental results revealed that the framework confined structure could effectively prevent the migration and aggregation of highly dispersed nanoparticles on catalyst. Benefiting from the structural advantages of ordered mesopores TiO2 (OMT), large specific surface area as well as abundant active sites could be supplied for catalytic reaction. It should be noted that citric acid pretreatment was essential for confined catalyst activation. The activation treatment could dramatically enhance catalyst surface acidity, especially a large number of strong acid sites were supplemented, resulting in significantly enhancement of catalytic activity at high temperature. Furthermore, it could also accelerate reduction of Ce4+ to Ce3+ and generate more active oxygen species, which resulted in a significant improvement in its low-temperature catalytic activity. Owning with strong surface acidity as well as framework confinement effect, the unique ordered mesoporous TiO2 framework could inhibit SO2 adsorption and protect active sites from SO2 attacking. Thus, the framework confined FW-CeW/OMT exhibited wide operating temperature window, good thermal stability, as well as strong sulfur resistance in NH3-SCR process.

Ordered and Isolated Pd Sites Endow Antiperovskite‐Type PdFe3N with High CO‐Tolerance for Formic Acid Electrooxidation

AbstractThe fundamental understanding and precise control of catalytic sites are challenging yet essential to explore advanced electrocatalysts for the formic acid oxidation reaction (FAOR). Herein, this work demonstrates a new and promising catalyst prototype of antiperovskite‐type PdFe3N which possesses ordered and isolated Pd sites. The as‐synthesized PdFe3N/N‐rGO exhibits significant enhancement in catalytic activity, robust stability, and Fe anti‐dissolution properties when compared with PdFe3/rGO and Pd/C. Density functional theory (DFT) calculations reveal that isolated and ordered Pd sites are beneficial for high formate coverage and thus suppressing CO formation/poisoning. Moreover, the strong Fe–N covalent bonds improve the vacancy formation energy of Fe, which ensures superior Fe anti‐dissolution properties. Beyond offering a promising candidate for catalyzing FAOR, these findings provide deeper insights into the structure of CO tolerance relationships and benefit the theory‐guided design of highly efficient catalysts.

Enhancing Catalytic Activity of a Nickel Single Atom Enzyme by Polynary Heteroatom Doping for Ferroptosis-Based Tumor Therapy

As a rising generation of nanozymes, single atom enzymes show significant promise for cancer therapy, due to their maximum atom utilization efficiency and well-defined electronic structures. However, it remains a tremendous challenge to precisely produce a heteroatom-doped single atom enzyme with an expected coordination environment. Herein, we develop an anion exchange strategy for precisely controlled production of an edge-rich sulfur (S)- and nitrogen (N)-decorated nickel single atom enzyme (S-N/Ni PSAE). In particular, sulfurized S-N/Ni PSAE exhibits stronger peroxidase-like and glutathione oxidase-like activities than the nitrogen-monodoped nickel single atom enzyme, which is attributed to the vacancies and defective sites of sulfurized nitrogen atoms. Moreover, both in vitro and in vivo results demonstrate that, compared with nitrogen-monodoped N/Ni PSAE, sulfurized S-N/Ni PSAE more effectively triggers ferroptosis of tumor cells via inactivating glutathione peroxidase 4 and inducing lipid peroxidation. This study highlights the enhanced catalytic efficacy of a polynary heteroatom-doped single atom enzyme for ferroptosis-based cancer therapy.

Sb-doped FeOCl nanozyme-based biosensor for highly sensitive colorimetric detection of glutathione.

Nanozymes have been emerging as substitutes for natural enzymes to construct biosensors towards biomolecular detection. However, the detection of glutathione (GSH) by nanozyme-based biosensors still remains agreat challenge for research on catalytic activity enhancement and thedetection mechanism. In this work, Sb-doped iron oxychloride (Sb-FeOCl) with awell-defined nanorod-like structure is prepared by high-temperature calcination. Sb-FeOCl nanorods have high peroxidase-like activity, which can catalyze the decomposition of H2O2 into ·OH and then oxidize 3,3',5,5'-tetramethylbenzidine (TMB). In view of these intriguing observations, a reliable colorimetric method with a simple mixing and detection strategy is developed for the detection of GSH. The linear range of GSH detection is 1-36μM. The detection limit of GSH reaches a low level of 0.495μM (3σ/slope). The GSH sensing system also exhibits excellent specificity and anti-interference. Taking advantage of the advantages of theSb-FeOCl nanorod-based biosensor, it can be used to quantitatively detect GSH levels in human serum. It can be anticipated that the Sb-FeOCl nanorods have broad prospects in the field of enzymatic biochemical reactions.

Boosting catalytic activity of SrCoO2.52 perovskite by Mn atom implantation for advanced peroxymonosulfate activation.

Material-enhanced heterogeneous peroxymonosulfate (PMS) activation for degradation of antibiotic in water has attracted intensive attention. However, one challenge is the electron transfer efficiency from the material to PMS for reactive oxygen species (ROS) production. Considering that the B-sites of perovskite oxides are closely associated with the catalytic performance, partial substitution of the B-sites of perovskite oxides can enhance the redox cycle of metals. Consequently, adjusting the ratio of each element at the B site can introduce oxygen vacancies on the surface of perovskite. Herein, a method was developed in which manganese (Mn) partially substitutes B-sites to modify surface properties of SrCoO2.52 perovskite oxides, resulting in the enhancement of catalytic activity. In degradation kinetics studies using SrCoMnO3-δ-0.5/PMS (SrCoMnO3-δ-0.5 denotes that the molar substitution of Mn at the B site of SrCoO2.52 perovskite oxide is 0.5) reaction system and sulfamethoxazole (SMX) as the target pollutant, it was found that the reaction rate constant (kobs) is 0.287min-1 which is 2.4 times that of SrCoO2.52/PMS system. Experimental and theoretical analyses revealed that Mn-O covalent bonding governs the intrinsic catalytic activity of SrCoMnO3-δ-0.5 perovskite oxides. The Mn sites exhibits stronger adsorption energy with PMS than the Co sites, facilitating the breaking of O-O bond. Simultaneously, oxygen vacancies and surface adsorbed oxygen species have a synergistic effect for PMS adsorption. This work can provide a potential route in developing advanced catalysts based on manipulation of the B-sites of perovskite oxides for PMS activation.

Enhancement of catalytic hydrolysis activity for organophosphates by the metal–organic framework MOF-808-NH2via post-synthetic modification

Post-synthetic modification of MOF-808 creates solid state buffering capacity for organophosphate catalytic hydrolysis.

Selective edge etching of Pd metallene for enhanced formic acid electrooxidation.

We develop a facile, selective edge etching strategy to create edge sites in Pd metallene using acetic acid. The created edge sites remarkably increase the electrochemically active surface area but reduce the charge transfer resistance, resulting in significant enhancement of catalytic activity and stability toward formic acid oxidation.