Ultrahigh Catalytic Activity Research Articles

Electrochemical biosensor for detection of MON89788 gene fragments with spiny trisoctahedron gold nanocrystal and target DNA recycling amplification.

Theshape-controlled synthesis of gold nanocrystals via shape induction of hexadecyltrimethylammonium chloride, potassium bromide, and potassium iodide and enantioselective direction of L-cysteineis reported. The resulting gold nanocrystals (STO-Au) offer spiny trisoctahedron nanostructures with good monodispersity and enhanced exposed high-index facets and high catalytic activity. Construction of the electrochemical sensing platform for MON89788 gene involves the modification of STO-Au, thionine (Thi), and labeled bipedal DNA probe 1 or 2 (P1 or P2) for target DNA-induced recycling amplification. In the detection, two surface DNA probes were immobilized on gold electrode via the Au-S bond. Then, hairpin DNA 1 (H1), Thi-STO-Au-P1, and Thi-STO-Au-P2 self-assemble into two-dimensional DNA nanopores (DNPs) on the electrode surface. Target DNA hybridizes with hairpin DNA 2 (H2) to open hairpin structure of H2. The opened H2 binds with H1 in the DNPs to release Thi-STO-Au-P1, Thi-STO-Au-P2, and target DNA by toehold-mediated strand-displacement. The utilization of target DNA-induced recycling allows one target DNA to release 2N STO-Au-labeled DNA strands, promoting significant signal amplification. The detection signal is further enhanced by the catalyzed redox reaction of Thi with STO-Au. The differential pulse voltammetric signal, best measured at - 0.18V vs. Ag/AgCl, decreases linearly with increasing concentration of MON89788 in the range 0.02-8 × 104 fM, and the detection limit is 0.0048 fM (S/N= 3). The proposed method was successfully applied for electrochemical detection of MON89788 gene fragments in the PCR products from genetically modified soybean. Graphical Abstract We develop l-cysteine controlled synthesis of spiny trisoctahedron gold nanocrystals with good monodispersity and highly exposed high-index facets. The architecture achieves to ultrahigh catalytic activity. The electrochemical biosensor based on gold nanocrystals and target DNA recycling amplification provides advantage of sensitivity, repeatability, and regeneration-free.

Free-standing nanoporous NiMnFeMo alloy: An efficient non-precious metal electrocatalyst for water splitting

Although significant progresses have been achieved recently in developing efficient catalysts for electrochemical water splitting, high performance catalysts toward hydrogen evolution and oxygen evolution in alkaline electrolyte at high current density (≧1000 mA cm−2) have been seldom realized. Herein, we report a flexible and free-standing nanoporous NiMnFeMo alloy (np-NiMnFeMo) with ultrahigh catalytic activity as both anode and cathode even at high current density. The nanoporous NiMnFeMo alloy can deliver as high as 1000 mA cm−2 at an overpotential of only 290 mV for hydrogen evolution reaction and 570 mV for oxygen evolution reaction. DFT calculations indicate that the ultrahigh HER activity of the catalyst is originated from the synergetic effect of the solid solution elements, where Ni atoms act as water dissociation center in the np-NiMnFeMo and the other metals (Mn, Fe and Mo) regulate the electronic structure and provide superior adsorption properties towards hydrogen. More importantly, the electrolyzer, assembled using the np-alloys as both cathode and anode for full water splitting, shows excellent stability.

Single Mn atom anchored on N-doped porous carbon as highly efficient Fenton-like catalyst for the degradation of organic contaminants

Fenton-like technology is a green pathway for removing recalcitrant organic pollutants from the environment. However, low catalytic efficiency and poor stability hinder the development of Fenton-like technology as a result of the lack of effective catalysts. Here, we report a highly efficient and stable Fenton-like catalyst based on isolated single Mn atom anchored on N-doped porous carbon. The catalyst exhibits high activity and stability in the heterogeneous activation of peroxymonosulfate (PMS) for organic pollutant degradation, showing an outstanding turnover frequency of greater than 5.69 min−1 in bisphenol A (BPA) degradation. A variety of analytical techniques as well as density functional theory (DFT) calculations suggest that the unique N-coordinated single Mn atom (MnN4) serves as a highly catalytically active site for PMS activation, while the adjacent pyrrolic N site acts as an adsorption site for the target organic molecules. The ultra-high catalytic activity of single Mn atom catalyst can be attributed to its fantastic dual reaction sites, which remarkably shorten the migration distance from the radical to the adsorbed organic molecules.

Holey Lamellar High-Entropy Oxide as an Ultra-High-Activity Heterogeneous Catalyst for Solvent-free Aerobic Oxidation of Benzyl Alcohol.

The development of noble-metal-free heterogeneous catalysts is promising for selective oxidation of aromatic alcohols; however, the relatively low conversion of non-noble metal catalysts under solvent-free atmospheric conditions hinders their industrial application. Now, a holey lamellar high entropy oxide (HEO) Co0.2 Ni0.2 Cu0.2 Mg0.2 Zn0.2 O material with mesoporous structure is prepared by an anchoring and merging process. The HEO has ultra-high catalytic activity for the solvent-free aerobic oxidation of benzyl alcohol. Up to 98 % conversion can be achieved in only 2 h, to our knowledge, the highest conversion of benzyl alcohol by oxidation to date. By regulating the catalytic reaction parameters, benzoic acid or benzaldehyde can be selectively optimized as the main product. Analytical characterizations and calculations provide a deeper insight into the catalysis mechanism, revealing abundant oxygen vacancies and holey lamellar framework contribute to the ultra-high catalytic activity.

Novel Architecture Titanium Carbide (Ti3C2Tx) MXene Cocatalysts toward Photocatalytic Hydrogen Production: A Mini-Review.

Low dimensional transition metal carbide and nitride (MXenes) have been emerging as frontier materials for energy storage and conversion. Ti3C2Tx was the first MXenes that discovered and soon become the most widely investigated among the MXenes family. Interestingly, Ti3C2Tx exhibits ultrahigh catalytic activity towards the hydrogen evolution reaction. In addition, Ti3C2Tx is electronically conductive, and its optical bandgap is tunable in the visible region, making it become one of the most promising candidates for the photocatalytic hydrogen evolution reaction (HER). In this review, we provide comprehensive strategies for the utilization of Ti3C2Tx as a catalyst for improving solar-driven HER, including surface functional groups engineering, structural modification, and cocatalyst coupling. In addition, the reaming obstacle for using these materials in a practical system is evaluated. Finally, the direction for the future development of these materials featuring high photocatalytic activity toward HER is discussed.

ZnCl2 salt facilitated preparation of FeNC: Enhancing the content of active species and their exposure for highly-efficient oxygen reduction reaction

Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditional carbonization process owing to Fe agglomeration and evaporation of N-contained small molecules. Besides, pyrolysis may make materials sintering which embeds a large number of active sites in the bulk phase and impedes direct exposure of reactive centers to the reactants. We here report that when calcinations, the addition of ZnCl 2 , an ordinary salt with very wide melting temperature range well covering the carbonization process of the precursor iron porphyrin, can significantly enhance the doping level of the active species and simultaneously create highly porous structures for FeNC catalysts. The obtained FeNC demonstrates ultrahigh catalytic activities even significantly better than Pt/C in oxygen reduction reaction. ZnCl 2 facilitated calcination functionalizes well in boosting the doping content of highly active species and constructing porous microstructures for FeNC catalysts.

MOF-derived Fe,Co@N–C bifunctional oxygen electrocatalysts for Zn–air batteries

MOF-derived Fe,Co@N-C bifunctional electrocatalysts for oxygen reduction reactions and oxygen evolution reactions have been prepared via a scalable method, exhibiting ultra-high catalytic activity and promising performance in Zn–air batteries.

Hollow Nanotube Ru/Cu2+1 O Supported on Copper Foam as a Bifunctional Catalyst for Overall Water Splitting.

Hydrogen energy is considered as one of the ideal clean energies for solving the energy shortage and environmental issues, and developing highly efficient electrocatalysts for overall water splitting to produce hydrogen is still a huge challenge. Herein, for the first time, Ru-doped Cu2+1 O vertically arranged nanotube arrays in situ grown on Cu foam (Ru/Cu2+1 O NT/CuF) are reported and further investigated for their catalytic properties for overall water splitting. The Ru/Cu2+1 O NT/CuF presents ultrahigh catalytic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions, and it exhibits a small overpotential of 32 mV at 10 mA cm-2 in the HER, and only needs 210 mV overpotential to achieve a current density of 10 mA cm-2 in the OER. Importantly, the alkaline electrolyzer using Ru/Cu2+1 O NT/CuF as a bifunctional electrocatalyst only needs 1.53 V voltage to deliver a current density of 10 mA cm-2 , which is much lower than the benchmark of IrO2 (+)/Pt(-) counterpart (1.64 V at 10 mA cm-2 ). The excellent performance of the Ru/Cu2+1 O NT/CuF catalyst is attributed to its high conductive substrate and special Ru-doped nanotube structure, which provides a high electrochemical active surface area and 3D gas diffusion channel.

Cobalt-based metal-organic frameworks promoting magnesium sulfite oxidation with ultrahigh catalytic activity and stability

In wet magnesia desulfurization, the ultrahigh stable catalysis of sulfite oxidation is a crucial step in byproduct reclaimation. In this study, a robust and efficient catalyst, Co-MOF-74(4), was synthesized through a facile solvothermal method with an optimal Co/ligand ratio of 4:1. The oxidation rate of magnesium sulfite catalyzed by Co-MOF-74(4) was >2.6 times higher than that of previously reported cobalt-based heterogeneous catalysts. Crucially, almost no attenuation of the catalytic activity was observed even after three reuse cycles. The properties of Co-MOF-74(4) before and after the reaction were characterized. Density functional theory calculations demonstrate that the unsaturated cobalt site on the open framework of Co-MOF-74(4) provides greater opportunity for active Co to be attacked by sulfite ions, resulting in the ultra-high catalytic activity of Co-MOF-74(4). In contrast to the conventional impregnated catalysts, the robust combination of active cobalt with ligands prohibits its stripping from the surface of Co-MOF-74(4) particles. The bond length, angle and lattice parameters have only slight changes after sulfite adsorption, which supports the stability of the catalyst in the reaction process.

Sub-10 nm Ag Nanoparticles/Graphene Oxide: Controllable Synthesis, Size-Dependent and Extremely Ultrahigh Catalytic Activity.

While tremendous advancements in Ag nanoparticle (AgNP)-based materials have been made, the development of a facile protocol for preparing sub-10 nm AgNPs with controllable size and ultrahigh performance remains a formidable challenge. It is shown that AgNPs/graphene oxide (AgNPs/GO) bearing 2.5, 4.3, and 6.2 nm AgNPs (2.5-AgNPs/GO, 4.3-AgNPs/GO, and 6.2-AgNPs/GO, respectively) could be fabricated via light-induced synthesis. Their catalytic activity toward 4-nitrophenol (4-NP) reduction, which is a "gold standard" for evaluating the performance of noble metal-based catalysts, is studied. When normalized by mole and area, the activity exhibits an order of 4.3-AgNPs/GO > 6.2-AgNPs/GO > 2.5-AgNPs/GO and 6.2-AgNPs/GO > 4.3-AgNPs/GO > 2.5-AgNPs/GO, respectively. This trend is a result of GO-induced electron concentration reduction with decreasing AgNP size. Significantly, under similar conditions, the activity of 4.3-AgNPs/GO is substantially superior to that of numerous state-of-the-art noble metal-based catalysts. The ultrafine size of the AgNPs and their surface accommodation on the unobstructed 2D GO scaffolds without capping reagents/covers, which make the abundantly exposed catalytically active sites highly accessible to substrate molecules, play an important role in their extremely ultrahigh performance. This work paves a new avenue for high-performance AgNP-based materials, and by taking 4-NP reduction as a proof-of-concept, provides new scientific insights into the rational design of surface-based advanced materials.

Hexagonal CuCo₂O₄ Nanoplatelets, a Highly Active Catalyst for the Hydrolysis of Ammonia Borane for Hydrogen Production.

Catalytic hydrolysis of ammonia borane (AB) has been considered as an effective and safe method to generate hydrogen. Development of highly active and low-cost catalysts is one of the key tasks for this technology. In this work, hexagonal CuCo2O4 nanoplatelets with a thickness of approximately 55 nm were prepared. In AB hydrolysis, those nanoplatelets exhibited ultrahigh catalytic activity with turnover frequency (TOF) of 73.4 molhydrogen min−1 molcat−1. As far as we know, this is one of the highest TOF values ever reported for non-noble metal catalysts. In addition, the effects of viscosity and different alkalis on the hydrolysis were also investigated. It is revealed that high viscosity of the reaction medium will retard the hydrolysis reaction. The presence of NaOH, KOH, and Na2CO3 in the reaction solution is favorable for hydrolytic process. In contrast, NH3·H2O will slow down the hydrolysis rate of ammonia borane. This work can provide some novel insight into the design of catalysts with both high performance and low cost. Besides, some findings in the present study can also offer us some information about how to improve the hydrolysis rates by optimizing the hydrolysis condition.

One-Step Rapid and Facile Synthesis of Subnanometer-Sized Pd6(C12H25S)11 Clusters with Ultra-High Catalytic Activity for 4-Nitrophenol Reduction

Palladium has aroused multitudinous concerns in recent years because of its highly catalytic activity with applications in many reactions. However, the synthesis of atomically precise Pd nanocluste...

Ni Nanoparticles on Ultrathin Mo2C Interconnected Nanonet: An Efficient 3D Hydrogen-Evolving Electrocatalyst with Superior Durability

Exploring efficient non-noble-metal electrocatalysts for hydrogen evolution reaction (HER) is becoming an urgent task owning to the persistently aggravating energy crisis. Herein, small Ni nanoparticles embedded in ultrathin Mo2C interconnected nanonet on carbon nanofibers (CF) were prepared for the first time. The Ni/Mo2C nanonet on CF (Ni/Mo2C/CF) carbonized under 650°C exhibits ultra-high catalytic activity which only needs 92 mV to afford 10 A/g with remarkable durability for HER in alkaline electrolyte.

Ultralow-temperature photochemical synthesis of atomically dispersed Pt catalysts for the hydrogen evolution reaction.

Efficient control of nucleation is a prerequisite for the solution-phase synthesis of nanocrystals. Although the thermodynamics and kinetics of the formation of metal nanoparticles have been largely investigated, fully suppressing the nucleation in solution synthesis remains a major challenge due to the high surface free energy of isolated atoms. In this article, we largely decreased the reaction temperature for ultraviolet (UV) photochemical reduction of H2PtCl6 solution to -60 °C and demonstrated such a method as a fast and convenient process for the synthesis of atomically dispersed Pt. We showed that the ultralow-temperature reaction efficiently inhibited the nucleation process by controlling its thermodynamics and kinetics. Compared with commercial platinum/carbon, the synthesized atomically dispersed Pt catalyst, as a superior HER catalyst, exhibited a lower overpotential of approximately 55 mV at a current density of 100 mA cm-2 and a lower Tafel slope of 26 mV dec-1 and had higher stability in 0.5 M H2SO4.

Ultrahigh Catalytic Activity of l-Proline-Functionalized Rh Nanoparticles for Methanolysis of Ammonia Borane.

The synthesis of ultrafine and well-distributed rhodium nanoparticles (NPs) with high efficiency toward methanolysis of ammonia borane (AB) is crucially important but challenging. A facile approach has been developed for synthesizing ultrafine and uniform Rh NPs deposited on carbon by using the small soluble organic molecule (SOM) of l-proline (PRO) as capping agent (Rh-PRO/C). The enrichment of N,O-coordination sites for the metal precursor by using PRO was found to be the key to the synthesis Rh-PRO/C. The as-prepared Rh-PRO/C showed high catalytic activity for ammonia borane methanolysis with the highest total turnover frequency (TOF) of 1035 mol (molRh min)-1 under basic conditions, which was three times higher than that of the state-of-the-art Rh-based catalysts. The excellent catalytic performance of Rh-PRO/C was ascribed to the well-dispersed Rh NPs and the PRO-functionalized metal surface, which can provide more active sites for the reaction. The merit of size-controlled synthesis combined with metal NP surface modification by SOMs is likely to be beneficial in various catalytic fields.

Preparation of Hollow Nitrogen Doped Carbon via Stresses Induced Orientation Contraction.

Hollow structured materials are widely applicable in various fields. Although many routes have been explored for getting such materials, a strategy mainly based on physical effect is still deficient. Herein, a "stresses induced orientation contraction" mechanism for preparation of hollow structures is reported. The composites constructed by zeolite imidazolate framework-8 (ZIF8) cores and polymerized dopamine (PDA) shells, upon annealing, form intensive interfacial interactions, which drag the ZIF8 cores outward to restrain their shrinkage. The gradually accumulated stresses in the central position of ZIF8 dodecahedron nanoparticles, then destroy the ZIF8 crystalline cores to form the hollow structures. In this stress-based route for creating hollow interiors with core-shell composites as the starting materials, three critical factors are necessary: 1) an intensive core-shell interfacial interaction; 2) the distinctly higher shrinkage degree of the cores than the shells; and 3) the relatively loose core structures. In oxygen reduction reaction (ORR) tested with three-electrode solution system and Zn-O2 battery, the achieved hollow nitrogen doped carbon (NC) demonstrates ultrahigh catalytic activities. This work gives an absolutely novel strategy for preparation of hollow structures, which may afford the exploration of a wider range of materials system with hollow interiors.

Palladium nanoclusters decorated partially decomposed porous ZIF-67 polyhedron with ultrahigh catalytic activity and stability on hydrogen generation

Metal-organic frameworks have attracted extensively attentions due to their unique structural properties such as high porosity, good crystallinity, and three-dimensional networking. However, to the best of our knowledge, there is no report concerning the application of partially decomposed metal-organic frameworks based catalyst for sodium borohydride hydrolysis for H2 generation. Herein, the partially decomposed cobalt-based zeolitic imidazolate frameworks supported Pd nanoclusters are fabricated by evaporation solvent assisted method followed by subsequent annealing under H2 atmosphere. Our results show that catalytic performance of the designed catalyst can be largely improved by optimizing the Pd loading and the annealing temperatures. The optimized catalyst exhibits a high catalytic activity towards hydrolysis of alkalized sodium borohydride with a specific H2 generation rate of 20.6 l min−1 mgPd−1 and turnover frequency of 495.0 mol min−1 molPd−1 at 25 °C, which is the highest reported so far among the similar catalysts. Moreover, the resulted catalyst also demonstrates a high level of stability. Based on structural characterization and experimental optimization, the extraordinary performance of the fabricated catalyst is mainly contributed to the synergetic effect of highly dispersed Pd nanoclusters with partially decomposed cobalt-based zeolitic imidazolate frameworks.

Cu0.6Ni0.4Co2O4 nanowires, a novel noble-metal-free catalyst with ultrahigh catalytic activity towards the hydrolysis of ammonia borane for hydrogen production

In this work, we have prepared a series of CuxNi1-xCo2O4 (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1) nanowires with a diameter of approximately 30 nm, which were characterized by X-ray powder diffractometry, scanning and transmission electron microscopy, and X-ray photoelectron spectrometry. For the first time, the catalytic activity of these CuxNi1-xCo2O4 nanowires in ammonia borane (AB) hydrolysis was investigated, and it was found that a significant synergistic effect exists between NiCo2O4 and CuCo2O4 in the hydrolytic reaction. Among these CuxNi1-xCo2O4 samples, the Cu0.6Ni0.4Co2O4 nanowires showed the highest turnover frequency (TOF) of 119.5 molhydrogen min−1 molcat−1. This value is 1.66 times as high as that for CoP nanoparticles, which is the most active noble-metal-free catalyst towards AB hydrolysis ever reported in the literature. Because of the low cost and high catalytic performance, the Cu0.6Ni0.4Co2O4 nanowires can be a robust catalyst towards AB hydrolysis in practical applications.

Facile Synthesis of Magnetic Hierarchical Core–Shell Structured Fe3O4@PDA‐Pd@MOF Nanocomposites: Highly Integrated Multifunctional Catalysts

AbstractA magnetic hierarchical core–shell structured Fe3O4@PDA‐Pd@[Cu3(btc)2] nanocomposite has been fabricated via a facile layer‐by‐layer assembly method. It contains a core of polydopamine (PDA)‐modified magnetic Fe3O4 nanoparticles (NPs), a transition layer of Pd NPs, and a porous outer shell of copper‐based metal–organic framework (MOF) with controllable thickness. This novel nanocomposite was characterized by TEM, FTIR, XRD, XPS, N2 adsorption–desorption isotherms, and VSM. The prepared Fe3O4@PDA‐Pd@[Cu3(btc)2] (n=5) nanocomposite shows ultrahigh catalytic activity for the 4‐nitrophenol reduction and Suzuki–Miyaura coupling reactions of aryl halides (Br, Cl) with arylboronic acids. Moreover, the nanocomposite also can be easily separated by an external magnet and reused at least 8 runs with excellent yields for both the reactions. The catalyst has outstanding catalytic performance, mainly because the integration of [Cu3(btc)2] with Fe3O4@PDA‐Pd that combines the advantages of each component could exhibit a synergistic effect in the catalytic system.

Pure Ni nanocrystallines anchored on rGO present ultrahigh electrocatalytic activity and stability in methanol oxidation.

Pure Ni nanoparticles with ultrafine size (2.3 ± 0.4 nm) embedded on rGO present ultrahigh catalytic activity (1600 mA mg-1), excellent stability (1020 mA mg-1 retained after 1000 cycles), and a saturation concentration (4 M) of methanol for methanol oxidation reactions, which is better than that of all previously reported Ni-based catalysts.