Improving the ammonia synthesis activity of Ru/CeO_(2) through enhancement of the metal–support interaction

The metal–support interactions induced by high-temperature hydrogen reduction have a strong influence on the catalytic performance of ceria-supported Ru catalysts. However, the appearance of the strong metal–support interaction leads to covering of the Ru species by Ce suboxides, which is detrimental to the ammonia synthesis reaction that requires metallic species as active sites. In the present work, the interaction between Ru and ceria in the Ru/CeO_(2) catalyst was induced by NaBH_(4) treatment. NaBH_(4) treatment enhanced the fraction of metallic Ru, proportion of Ce^(3+), content of exposed Ru species, and amount of surface oxygen species. As a result, a larger amount of hydrogen species would desorb by the H_(2)-formation pathway and the strength of hydrogen adsorption would be weaker, weakening the inhibition effect of the hydrogen species on ammonia synthesis. In addition, the strong electronic metal–support interaction aids in nitrogen dissociation. Consequently, Ru/CeO_(2) with NaBH_(4) treatment showed higher ammonia synthesis rates than that with only hydrogen reduction.

A Review on Metal-support Interaction in Automotive Catalysts

TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the active component, and inorganic oxides such as γ-alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ) and ceria-zirconia (CeO 2-ZrO 2 ) are used as the support. Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs. The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature. In the same, precious metals can also enhance the redox performance and oxygen storage capacity of support. This paper reviews the reaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and supports such as Al 2 O 3 , CeO 2-based composite oxides.

Modulating metal-support interaction between Pt_(3)Ni and unsaturated WOx to selectively regulate the ORR performance

Tuning strong metal-support interaction between Pt-based alloys and metal oxides is an effective strategy for modulating the performance of oxygen reduction reaction(ORR).Herein,Pt_(3)Ni alloy anchored on WO_(x) with different content of oxygen vacancies is synthesized,and the effect of unsaturated WO_(x) on ORR activity/stability is revealed.Electrochemical results indicate that ORR activity is positively correlated with oxygen vacancy concentration,while durability presents the opposite trend.Density functional theory(DFT)calculation results suggest that controlling the content of oxygen vacancies can usefully adjust the charge redistribution between Pt_(3)Ni and WO_(x),which can optimize the adsorption/activation of reactants,thus obtaining good ORR activity.This study uncovers the effect of unsaturated WO_(x) on ORR performance for Pt-based alloys and provides a promising strategy to design efficient and stable ORR catalysts.

Graphdiyne oxide substrate-enhanced peroxidase-mimicking performance of Ru nanoparticles with physiological pH preference

Modulating electronic structure of metal nanoparticles via metal–support interaction has attracted intense interest in the field of catalytic science.However,the roles of supporting substrates in regulating catalytic properties of nanozymes remain elusive.In this study,we find that the use of graphdiyne oxide(GDYO)as the substrate for self-terminating growth of Ru nanoparticles(Ru@GDYO)endows the peroxidase-like activity of Ru nanoparticles with intrinsic physiological pH preference and natural horseradish peroxidase(HRP)comparable performance.Ru nanoparticles electrolessly deposited onto GDYO possess a partially oxidized electronic structure owing to limited charge transfer between Ru and GDYO,contributing to the intrinsic physiological pH preference of the peroxidase-mimicking nanozyme.More importantly,the substrate GDYO plays an influential factor in enhancing catalytic activity,that is,the activity of Ru@GDYO is much higher than that of Ru nanoparticles deposited on other carbon substrates including graphene oxides and graphdiyne.To demonstrate the application of Ru@GDYO nanozyme in neutral solutions,we employ Ru@GDYO with nicotinamide adenine dinucleotide(NAD+)-dependent dehydrogenases in physiological conditions to realize a sustainable cascade reaction by means of forming continuous NAD^(+)/dihydronicotiamide adenine dinucleotide(NADH)recycling.Our finding represents a promising perspective on designing high-performance peroxidase-mimicking nanozymes with broader applicability,raising fundamental understanding of structure–activity relationship,and investigating new applications of nanozymes in biological systems.

Incorporating Sulfur Atoms into Palladium Catalysts by Reactive Metal–Support Interaction for Selective Hydrogenation

Developing highly active and selective catalysts for the hydrogenation of nitroarenes,an environmentally benign process to produce industrially important aniline intermediates,is highly desirable but very challenging.Pd catalysts are generally recognized as active but nonselective catalysts for this important reaction.Here,we report an effective strategy to greatly improve the selectivity of Pd catalysts based on the reactive metal–support interaction.

Wet-milling synthesis of immobilized Pt/Ir nanoclusters as promising heterogeneous catalysts

Being a typical state of the art heterogeneous catalyst,supported noble metal catalyst often demonstrates enhanced catalytic properties.However,a facile synthetic method for realizing large-scale and low-cost supported noble metal catalyst is strictly indispensable.To this end,by making use of the strong metal-support interaction(SMSI)and mechanochemical reaction,we introduce an efficient synthetic route to obtain ultrafine Pt and Ir nanoclusters immobilized on diverse substrates by wet chemical milling.We further demonstrate the scaling-up effect of our approach by large-scale ball-milling production of Pt nanoclusters immobilized on TiO_(2)substrate.The synthesized Pt/Ir@Co_(3)O_(4)catalysts exhibit superior oxygen evolution reaction(OER)performance with only 230 and 290 mV overpotential to achieve current density of 10 and 100 mA·cm^(-2),beating the catalytic performance of Co_(3)O_(4)supported Pt or Ir clusters and commercial Ir/C.It is envisioned that the present work strategically directs facile ways for fabricating supported noble metal heterogeneous catalysts.

Interactive Decision Support Algorithm and Its Application

On the bases of the properties of abstract hierarchical structure model and the concrete structure of the mode1 system. which is convenient to solve practical problems, a visual interactive hierarchical coordination method has been proposed. In this paper, a compensation adjustment sub-mode1 for hydropower stations, an optimal operation sub-model for hydro-thermal power systems, and an aggregation model based on the aspiration level theory are built, and these models can be solved with decision support algorithm. The set of objectives and its structure could be made by the decision-maker in visua1 software, which could be decided by AHP. Finally, the application results show that this methodology is feasible, however, the software (DSS) needs further improvement.