Ultrahigh Activity Research Articles

Formamide-soluble solid-state ZnO as Zn source for synthesizing FeCo–NC with ultrahigh oxygen reduction reaction activity

Cost/time-efficient synthesis of highly dispersed M–N–C electrocatalysts was established using solid-state ZnO as new Zn source, rendering superior ORR (Eonset ∼ 1.05 V and E1/2 ∼ 0.92 V) and Al–air battery performance.

Ligand Engineering in Nickel Phthalocyanine to Boost the Electrocatalytic Reduction of CO2

AbstractDesigning and synthesizing efficient molecular catalysts may unlock the great challenge of controlling the CO2 reduction reaction (CO2RR) with molecular precision. Nickel phthalocyanine (NiPc) appears as a promising candidate for this task due to its adjustable Ni active‐site. However, the pristine NiPc suffers from poor activity and stability for CO2RR owing to the poor CO2 adsorption and activation at the bare Ni site. Here, a ligand‐tuned strategy is developed to enhance the catalytic performance and unveil the ligand effect of NiPc on CO2RR. Theoretical calculations and experimental results indicate that NiPc with electron‐donating substituents (hydroxyl or amino) can induce electronic localization at the Ni site which greatly enhances the CO2 adsorption and activation. Employing the optimal catalyst—an amino‐substituted NiPc—to convert CO2 into CO in a flow cell can achieve an ultrahigh activity and selectivity of 99.8% at current densities up to −400 mA cm−2. This work offers a novel strategy to regulate the electronic structure of active sites by ligand design and discloses the ligand‐directed catalysis of the tailored NiPc for highly efficient CO2RR.

Crystal Orientation in Pt-Based Alloys Induced by W(CO)6: Driving Oxygen Electroreduction Catalysis.

Integrating crystal orientation as well as structural and compositional advantages into one catalyst might be a promising strategy for high-performance Pt-based catalysts for proton-exchange membrane fuel cells. Herein, by introducing W(CO)6 as a structure-oriented template, Pt-based alloys with a well-defined crystal orientation along the (111) facet were obtained. The oxygen reduction reaction mass and specific activities of the crystal-facet-tuned alloys reach a new level. Moreover, the outstanding durability stems from the combination of their exposed crystal facets and incorporated W. The density functional theory calculation results reveal that the formation of the preferred (111) alloys can be attributed to the lower free energy of (111) facets and the weaker adsorption of CO released by W(CO)6. This proposed synthesis strategy of using transition-metal carbonyl compounds as additives to synthesize alloys with strong crystal orientation may open a door to the design of various alloy catalysts with ultrahigh activity.

Rational Design of Highly Stable and Active MXene-Based Bifunctional ORR/OER Double-Atom Catalysts.

Designing highly active and bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts has attracted great interest toward metal-air batteries. Herein, an efficient solution to the search for MXene-based bifunctional catalysts is proposed by introducing non-noble metals such as Fe/Co/Ni at the surfaces. These results indicate that the ultrahigh activities in Ni1/Ni2- and Fe1/Ni2-modified MXene-based double-atom catalysts (DACs) for bifunctional ORR/OER are better than those of well-known unifunctional catalysts with low overpotentials, such as Pt(111) for the ORR and IrO2 (110) for the OER. Strain can profoundly regulate the catalytic activities of MXene-based DACs, providing a novel pathway for tunable catalytic behavior in flexible MXenes. An electrochemical model, based on density functional theory and theoretical polarization curves, is proposed to reveal the underlying mechanisms, in agreement with experimental results. Electronic structure analyses indicate that the excellent catalytic activities in the MXene-based DACs are attributed to the electron-capturing capability and synergistic interactions between Fe/Co/Ni adsorbents and MXene substrate. These findings not only reveal promising candidates for MXene-based bifunctional ORR/OER catalysts but also provide new theoretical insights into rationally designing noble-metal-free bifunctional DACs.

Synergistic ultra-high activity of double B doped graphyne for electrocatalytic nitrogen reduction

The electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is an emerging technique to address energy shortages and climate change. Thus, developing efficient but low-cost electrocatalysts is important. In the present paper, we applied γ-graphyne (γGy) doped with B, N, O, P and S as NRR catalysts, and the activities of these catalysts were studied by extensive density functional theory (DFT) calculations. Our results suggest that single N, O, P and S doping are not effective in enhancing γGy NRR activity, and the γGy with B(sp2)-C(sp)-B(sp) configuration has excellent overall NRR activity with a record low limiting potential (−0.12 V), good conductivity, low hydrogen evolution reaction activity and high dynamic stability. We revealed that the sp-C directly connected to active sp-B can be an energy buffer that makes a flat potential energy surface. Overall, our research provides several good NRR catalysts by carefully controlling the doping sites and provides a new strategy for further development of metal-free catalysts for the NRR.

Ultrahigh activity of molybdenum/vanadium-doped Ni-Co phosphides nanoneedles based on ion-exchange for hydrogen evolution at large current density

Heteroatom doping is a promising strategy to optimize the electronic structure of transition metal phosphides so enhancing the hydrogen evolution reaction (HER). However, complex and harsh experimental design is often required to achieve homogeneous doping of corresponding elements while achieving the best regulating effect. Herein, a facile ion-exchange (IE) strategy is applied to dope Mo/V species evenly into Ni-Co phosphides under mild conditions while maintaining the nanoneedle morphology. The electrochemical characterization verifies Mo dopants have a better electronic regulation effect on NiCoP crystal than V dopants, corresponding to the better hydrogen evolution performance of Mo-NiCoP/NF. Notably, due to the highly dispersed nanoneedle morphology, the synergistic effect of Ni-Co phosphides, and the optimized electronic structure, Mo-NiCoP/NF demonstrates a higher activity than that of the noble metal Pt/C at the high current density (>99 mA cm−2). The present work is supposed to open new sights for the development of high-performance catalysts by ion-exchange strategy.

Co/N-codoped porous carbons derived from poly(Schiff base)/Co(II) complex as ultrahighly efficient catalysts for CTH of nitroarenes

Herein we report the scalable synthesis of Co/N-codoped porous carbon (Co/N-C) catalysts by pyrolyzing poly(Schiff base)/Co(II) complex. The strong Co(II)-binding affinity of poly(Schiff base) leads to the formation of uniformly distributed Co(0) nanoparticles, Co-Nx species, and N–C configurations, in which their catalytic contributions are confirmed and estimated by ligand-poisoning and acid-etching experiments and the Co-Nx species has been proved to be highly active for catalytic transfer hydrogenation (CTH) reaction. Consequently, the as-prepared Co-N/C-950 catalyst exhibits an ultrahigh activity for the CTH of 4-nitrophenol (4-NP) with a TOF of 226 mol4-NP molCo−1 min−1 (13560 h−1) together with an excellent selectivity for CTH of challenging nitroarenes. Moreover, the Co(0) nanoparticles embedded in the Co-N/C-950 catalyst can be further transformed to Co4N phase by a facile nitridation reaction, yielding Co4N-N/C-950 catalyst with even higher activity for the CTH of 4-NP (TOF up to 310 mol4-NP molCo−1 min−1).

Atomic interface engineering: Strawberry-like RuO2/C hybrids for efficient hydrogen evolution from ammonia borane and water

Efficient hydrogen production plays a key role in establishing hydrogen economy in the current world. In this study, we fabricated ultrafine RuO2 nanoparticles on carbon black to form a strawberry-like RuO2/C hybrid, using by a solid-phase grinding and subsequent low-temperature annealing. The synthesized hybrid displays very low reaction activation energy (28.5 KJ mol−1) for hydrogen evolution from ammonia borane. In case of hydrogen evolution from alkaline water, it also exhibits a remarkably improved electrocatalytic activity than a commercial Pt/C, with an ultra-low overpotential of 8 mV (at 10 mA cm−2). For the above bifunctional catalyst, the formed C–Ru–C bonds between the ruthenium oxide and carbon result in the ultrahigh activity of the hybrid, as evidenced by DFT results. This work offers a guideline to synthesize efficient metal-based (Ru, Pd, Rh, Ir, Au, etc.) catalysts with smart structures for catalysis.

Chloridion-induced dual tunable fabrication of oxygen-deficient Bi2WO6 atomic layers for deep oxidation of NO

Engineering an efficient interface is a trustworthy strategy for designing advanced photocatalytic systems for solar energy conversion. Herein, oxygen-deficient Bi2WO6 atomic layers without organic residues were successfully fabricated via a facile solvothermal strategy by the multifunctional regulatory mechanism of introduced chloridion. Both DFT calculations and speciation determination revealed that chloridion displayed a more pronounced effect in the controllable synthesis of oxygen-deficient Bi2WO6 atomic layers without organic residues: ultrathinning and defect-engineering. This built-in multi-cooperative interface endowed Bi2WO6 with intriguing photoelectrochemical properties, O2 activation ability, and ultrahigh activity in visible-light powered deep oxidation of NO. A reasonable photocatalytic mechanism was proposed based on in situ infrared spectroscopy analysis and theoretical calculations. We believe that this multi-cooperative interface engineering of oxygen-deficient Bi2WO6 atomic layers without organic residues could provide new insights into the design of two-dimensional (2D) layered materials with efficient active sites and pave the way for efficient NO photooxidation systems.

Constructing ultrathin FeS/FeOxH@Fe nano-sheets for highly efficient oxygen evolution reaction

Exploring earth-abundant catalysts with ultra-high activity and durability are the decisive challenges for oxygen evolution reaction. This work prepared the FeS/FeOxH@Fe nanosheets as the efficient and stable electrocatalysts of oxygen evolution reaction (OER) through a simple one-step co-deposition method. The FeS/FeOxH@Fe exhibited small overpotentials of 245, 376 and 482 mV at the current density of 10, 500 and 1000 mA cm−2 without iR-compensations in 1.0 M KOH solution, respectively. Constructing amorphous structure and the interface between amorphous and crystal can obviously improve the conductivity of FeOxH, which is beneficial to the improvement of catalytic performance. This work may provide an effective and controlled strategy to design highly active OER catalysts with an interface structure between amorphous and crystal by a well-designed co-deposition.

General molten-salt route to three-dimensional porous transition metal nitrides as sensitive and stable Raman substrates

Transition metal nitrides have been widely studied due to their high electrical conductivity and excellent chemical stability. However, their preparation traditionally requires harsh conditions because of the ultrahigh activation energy barrier they need to cross in nucleation. Herein, we report three-dimensional porous VN, MoN, WN, and TiN with high surface area and porosity that are prepared by a general and mild molten-salt route. Trace water is found to be a key factor for the formation of these porous transition metal nitrides. The porous transition metal nitrides show hydrophobic surface and can adsorb a series of organic compounds with high capacity. Among them, the porous VN shows strong surface plasmon resonance, high conductivity, and a remarkable photothermal conversion efficiency. As a new type of corrosion- and radiation-resistant surface-enhanced Raman scattering substrate, the porous VN exhibits an ultrasensitive detection limit of 10−11 M for polychlorophenol.

Rational Fabrication of Low-Coordinate Single-Atom Ni Electrocatalysts by MOFs for Highly Selective CO2 Reduction.

Single-atom catalysts (SACs) have attracted tremendous interests due to their ultrahigh activity and selectivity. However, the rational control over coordination microenvironment of SACs remains a grand challenge. Herein, a post-synthetic metal substitution (PSMS) strategy has been developed to fabricate single-atom Ni catalysts with different N coordination numbers (denoted Ni-Nx -C) on pre-designed N-doped carbon derived from metal-organic frameworks. When served for CO2 electroreduction, the obtained Ni-N3 -C catalyst achieves CO Faradaic efficiency (FE) up to 95.6 %, much superior to that of Ni-N4 -C. Theoretical calculations reveal that the lower Ni coordination number in Ni-N3 -C can significantly enhance COOH* formation, thereby accelerating CO2 reduction. In addition, Ni-N3 -C shows excellent performance in Zn-CO2 battery with ultrahigh CO FE and excellent stability. This work opens up a new and general avenue to coordination microenvironment modulation (MEM) of SACs for CO2 utilization.

Rational Fabrication of Low‐Coordinate Single‐Atom Ni Electrocatalysts by MOFs for Highly Selective CO2 Reduction

AbstractSingle‐atom catalysts (SACs) have attracted tremendous interests due to their ultrahigh activity and selectivity. However, the rational control over coordination microenvironment of SACs remains a grand challenge. Herein, a post‐synthetic metal substitution (PSMS) strategy has been developed to fabricate single‐atom Ni catalysts with different N coordination numbers (denoted Ni‐Nx‐C) on pre‐designed N‐doped carbon derived from metal‐organic frameworks. When served for CO2 electroreduction, the obtained Ni‐N3‐C catalyst achieves CO Faradaic efficiency (FE) up to 95.6 %, much superior to that of Ni‐N4‐C. Theoretical calculations reveal that the lower Ni coordination number in Ni‐N3‐C can significantly enhance COOH* formation, thereby accelerating CO2 reduction. In addition, Ni‐N3‐C shows excellent performance in Zn–CO2 battery with ultrahigh CO FE and excellent stability. This work opens up a new and general avenue to coordination microenvironment modulation (MEM) of SACs for CO2 utilization.

A highly efficient atomically thin curved PdIr bimetallene electrocatalyst.

The multi-metallene with an ultrahigh surface area has great potential in precise tuning of surface heterogeneous d-electronic correlation by surface strain effect for the distinctive surface electronic structure, which is a brand new class of promising 2D electrocatalyst for sustainable energy device application. However, achieving such an atomically thin multi-metallene still presents a great challenge. Herein, we present a new synthetic method for an atomic-level palladium-iridium (PdIr) bimetallene with an average thickness of only ∼1.0 nm for achieving superior catalysis in the hydrogen evolution reaction (HER) and the formic acid oxidation reaction (FAOR). The curved PdIr bimetallene presents a top-ranked high electrochemical active area of 127.5 ± 10.8 m2 gPd+Ir−1 in the reported noble alloy materials, and exhibits a very low overpotential, ultrahigh activity and improved stability for HER and FAOR. DFT calculation reveals that the PdIr bimetallene herein has a unique lattice tangential strain, which can induce surface distortion while concurrently creating a variety of concave-convex featured micro-active regions formed by variously coordinated Pd sites agglomeration. Such a strong strain effect correlates the abnormal on-site active 4d10-t2g-orbital Coulomb correlation potential and directly elevates orbital-electronegativity exposure within these active regions, resulting in a preeminent barrier-free energetic path for significant enhancement of FAOR and HER catalytic performance.

Porous selenium nanozymes targeted scavenging ROS synchronize therapy local inflammation and sepsis injury

Excessive reactive oxygen species (ROS) is the main factor leading to high mortality in local inflammation and sepsis. Therefore, developing efficient ROS scavenger in pro-inflammatory immune cells is an urgent strategy for therapy local inflammatory and sepsis injury. Herein, we constructed a novel mesoporous selenium-hyaluronic acid nanoenzyme therapeutic system (MSe-HA NPs) for therapy local inflammatory and sepsis injury by targeting eliminate ROS in inflammatory macrophage. In detail manners, the high specific surface area of mesoporous selenium nanoenzyme exhibited ultra-high activity like glutathione peroxidase (GPx), which catalytic speed of H2O2 scavenging was increasing to 2.02 times compare with solid Se NPs. Moreover, the broad spectrum of ROS eliminating capacity further promoted ability of MSe NPs in eliminating various ROS. More interestingly, we found that choose HA as the modification not only endowed the MSe NPs targeting to inflammatory macrophage, but the ROS degradable property of HA could enhance the MSe NPs to eliminating ROS. In vivo, MSe-HA NPs after injection showed that simultaneously cured the local inflammation and sepsis induced with LPS by quickly eliminating excessive ROS. Especially in sepsis mouse models, the survival rate and the organic dysfunction significantly improved after treated with MSe-HA NPs. Thus, this novel mesoporous nanozyme provides an effective strategy for the design of nanomedicine and the treatment of inflammation-related diseases.

Facile synthesis of highly crystalline g-C3N4 nanosheets with remarkable visible light photocatalytic activity for antibiotics removal

g-C3N4 has attracted much attention in photocatalysis field because of its good visible light response. However, its photocatalytic activity is still greatly limited by fast carriers recombination and small specific surface. In order to promote carriers separation and pollutants adsorption, a facile synthesis scheme combining hydrothermal method with secondary calcination process under N2 gas protection was developed, and highly crystalline g-C3N4 nanosheets (HCCNNS) were successfully prepared. During ciprofloxacin (CIP) and sulfamethazine (SMZ) degradation, it showed excellent visible light photocatalytic activity, wherein CIP and SMZ with 10 mg/L could achieve degradation efficiency of 98.4% and 96.9% in 60 min under visible light irradiation. Compared with conventional g-C3N4, the degradation rate constants were enhanced by 6.9 and 5.8 times, respectively. From the perspectives of morphology, optical property and surface chemistry, the ultra-high activity of HCCNNS is mainly attributed to its highly crystalline structure and nanosheet morphology, which not only reduce the carriers transfer resistance, promote the pollutants adsorption capability, but also expand the light absorption range, and promote the carriers separation. Furthermore, the synthesis procedure of HCCNNS possesses the nature of high yield and excellent cost performance, thus, HCCNNS possesses great potential for mass production and practical application for antibiotics removal.

Ultralow loading of ruthenium nanoparticles on nitrogen-doped porous carbon enables ultrahigh mass activity for the hydrogen evolution reaction in alkaline media

Carbon-supported ultrafine Ru nanoparticles with 0.44 wt% Ru loading displayed ultrahigh activity towards hydrogen evolution reaction in alkaline media.

Аномальные кинетические характеристики транспорта водорода через Pd-Cu-мембраны, модифицированные пентадвойникованными цветкообразными нанокристаллитами с высокоиндексными гранями

A technique that made it possible for the first time to achieve fivefold symmetry in palladium nanocrystallites grown on the surface of a Pd-Cu film has been developed. Pd-40%Cu membrane modification with pentatwinned nanocrystallites with high-index facets made it possible to achieve ultra-high hydrogen permeability up to 10.1 mmol s-1 m-2 at 100 °C. Such permeability, comparable in value to high-temperature analogs, is anomalous, since the predicted values should be more than 2 times lower than those obtained. This result is due to the acceleration of surface dissociative adsorption and recombinative desorption as a result of the pentatwinned particles ultra-high activity in reactions involving hydrogen, which is confirmed by the data on the selectivity of the developed membranes.

Synthesis of rattle-structured CuCo2O4 nanospheres with tunable sizes based on heterogeneous contraction and their ultrahigh performance toward ammonia borane hydrolysis

Micro/nano-materials with rattle-type structures are attractive because of their unique physicochemical properties and extensive applications. In this study, well-defined rattle-type CuCo2O4 nanospheres were fabricated by heterogeneous contraction caused by non-equilibrium heat treatment with the assistance of an RF (resorcinol formaldehyde) resin colloidal sphere hard template. The sizes of CuCo2O4 nanospheres could be tuned by varying the amount of NH3·H2O used during template synthesis. The possible formation mechanism of rattle-type CuCo2O4 nanospheres was also proposed. When used in ammonia borane hydrolysis, rattle-type CuCo2O4 nanospheres exhibited ultrahigh activity with a turnover frequency of 104.0 min−1, which is one of the highest activities of non-noble-metal based catalysts, and is even higher than many noble-metal-based catalysts. This research provides valuable insights into the development of robust catalysts for ammonia borane hydrolysis. In addition, the synthetic method presented in this work can be easily extended to prepare other oxide composites with rattle structures.

Ultra-high resolution mapping and ablation of accessory pathway conduction.

Detailed mapping studies of accessory pathway (AP) conduction have not been previously performed using ultra-high resolution mapping systems. We sought to evaluate the clinical utility of ultra-high resolution mapping systems and the novel "Lumipoint" algorithm in AP ablation. This study included 17 patients who underwent AP mapping using minielectrode basket catheters and Rhythmia systems. Ablation was performed with 4-mm irrigated-tip catheters. Antegrade and retrograde AP conduction was observed in 6 and 16 patients. Atrial activation map was obtained during orthodromic tachycardia and ventricular pacing in 13 (76.5%) and 14 (82.3%) patients, and the earliest activation area was identical. Ventricular activation maps were created during atrial pacing in 3 patients. All maps showed focal activation patterns on global activation histograms, and the valley on the histogram highlighted the earliest activation area. "Complex activation" features further highlighted limited areas with continuous electrical activity during the time period in the majority. APs were located at the mitral and tricuspid annuli in 15 and 2 patients, and all were successfully eliminated with 3.4 ± 0.6s applications. No patients had recurrences during a median follow-up of 15 [10.5-22.5] months. At successful ablation sites, the local atrial and ventricular electrogram amplitudes and ratio tended to be greater, and fusion or continuous electrical activity between the atrial and ventricular components was more frequently observed on the minielectrode than ablation catheter (17/17 vs. 12/17, p = 0.005). Ultra-high resolution activation mapping and a novel algorithm facilitated the AP localization. The local electrogram characteristics differed between the minielectrode and ablation catheters.