Dual-site collaboration boosts electrochemical nitrogen reduction on Ru-S-C single-atom catalyst

Electrocatalytic reduction of nitrogen into ammonia(NH_(3))is a highly attractive but challenging route for NH_(3)production.We propose to realize a synergetic work of multi reaction sites to overcome the limitation of sustainable NH_(3)production.Herein,using ruthenium-sulfur-carbon(Ru-S-C)catalyst as a prototype,we show that the Ru/S dual-site cooperates to catalyse eletrocatalytic nitrogen reduction reaction(eNRR)at ambient conditions.With the combination of theoretical calculations,in situ Raman spectroscopy,and experimental observation,we demonstrate that such Ru/S dual-site cooperation greatly facilitates the activation and first protonation of N_(2)in the rate-determining step of eNRR.As a result,Ru-S-C catalyst exhibits significantly enhanced eNRR performance compared with the routine Ru-N-C catalyst via a single-site catalytic mechanism.We anticipate that our specifically designed dual-site collaborative catalytic mechanism will open up a new way to offers new opportunities for advancing sustainable NH_(3)production.

Cyclohexanol optimizes Pt/ionomer interface in fuel cell cathodes

This highlight is based on a recent article published in Nature Catalysis, in which Wei's group [1] from Chongqing University proposes a novel approach to enhance the performance of proton exchange membrane fuel cells(PEMFCs)by adjusting the interface between Pt and ionomer in the cathode catalyst layer. Their strategy involves adding cyclohexanol to the cathode catalyst ink to impede the adsorption of sulfonate groups from the ionomer onto Pt nanoparticles, which results in the release of Pt activity sites and a significant improvement in the mass transport efficiency.

Alloy strategy to synthesize Pt-early transition metal oxide interfacial catalysts

Metal oxide supported metal catalysts show promising catalytic performance in many industry-relevant reactions.However,the enhancement of performance is often limited by the insufficient metal/metal oxide interface.In this work,we demonstrate a general synthesis of Pt-early transition metal oxide(Pt-MO_(x),M=Ti,Zr,V,and Y)catalysts with rich interfacial sites,which is based on the air-induced surface segregation and oxidation of M in the supported Pt-M alloy catalysts.Systematic characterizations verify the dynamic structural response of Pt-M alloy catalysts to air and the formation of Pt-MO_(x) catalysts with abundant interfacial sites.The prepared Pt-TiO_(x) interfacial catalysts exhibit improved performance in hydrogenation reactions of benzaldehyde,nitrobenzene,styrene,and furfural,as a result of the heterolytic dissociation of H_(2) at Pt-metal oxide interfacial sites.

A low-melting-point metal doping strategy for the synthesis of small-sized intermetallic Pt_(5)Ce fuel cell catalysts

Carbon-supported platinum-lanthanum(Pt-Ln)intermetallic compound(IMC)nanoparticles with high activity and robust stability have been demonstrated as promising cathode catalysts for proton-exchange membrane fuel cells.However,the preparation of Pt-Ln IMC catalysts needs high-temperature annealing treatment that inevitably causes nanoparticle sintering,resulting in significant reduction of the electrochemical surface area and mass-based activity.Here,we prepare small-sized M-doped Pt_(5)Ce(M=Ga,Cd,and Sb)IMCs catalysts via a low-melting-point metal doping strategy.We speculate that the doping of low-melting-point metals can facilitate the generation of vacancies in the crystal lattice through thermal activation and thus reduce the kinetic barriers for the formation of intermetallic Pt_(5)Ce catalysts.The prepared Ga-doped Pt_(5)Ce catalyst exhibits a higher electrochemical active surface area(81 m^(2)·gPt^(-1))and a larger mass activity(0.45 A·mgPt^(-1)at 0.9 V)over the undoped Pt_(5)Ce and commercial Pt/C catalysts.In the membrane electrode assembly test,the Ga-doped Pt_(5)Ce cathode delivers a power density of 0.98 W·cm^(-2)at 0.67 V,along with a voltage loss of only 27 mV at 0.8 A·cm^(-2)at the end of accelerated stability test.

Synthesis of hierarchically porous carbon materials by zinc salts-assisted carbonization of biomass and organic solid wastes

Hierarchically porous carbons(HPCs)with multimodal pores have attracted considerable attention due to their unique physical and chemical properties and various application potentials in heterogeneous catalysis,environmental treatment,and energy storage and conversion.Herein,we report a general and simple zinc salts-assisted method for the synthesis of HPCs with varied porosity and chemical func-tionalities by the direct carbonization of diverse biomass and wastes.During the carbonization,zinc salts are thermally decomposed into nanoparticles that serve as in-situ templates to introduce nanopores in carbons.The prepared HPCs exhibit high specific surface areas(up to 2432 m2 g-1),large pore volumes(up to 4.30 cm^(3)g^(-1)),and broad pore size distributions.Moreover,the zinc salts can be recovered and recycled,supporting the sustainable production of HPCs on large scale.The prepared HPCs-supported catalysts with atomically dispersed metal sites exhibit promising electrocatalytic performance for the oxygen reduction reaction.

Bulky nanodiamond-confined synthesis of sub-5 nanometer ordered intermetallic Pd_(3)Pb catalysts

Modulation of geometric and electronic structures of supported Pd-based catalysts by forming atomically ordered intermetallic phases enables an effective way to optimize catalytic performance.However,the synthesis of small-sized Pd-based intermetallic nanoparticle catalysts with improved mass-based activity remains formidable challenges,since high-temperature annealing generally required for atom ordering inevitably leads to severe metal sintering and thus large crystallites.Here,we present a bulky nanodiamond-confined method to prepare sub-5 nm Pd_(3)Pb intermetallic nanocatalysts by mitigating metal sintering at high temperatures,which is induced by the electronic interactions between metal and defect-rich graphene shells reinforced by diamond cores in the bulky nanodiamond support.The prepared small-sized Pd_(3)Pb intermetallic catalyst displays a high activity with a turnover frequency of 932 h−1 for the semihydrogenation of phenylacetylene under mild conditions(room temperature,3 bar H_(2)),along with a high selectivity of>96%to styrene near the complete conversion of phenylacetylene.

A library of carbon-supported ultrasmall bimetallic nanoparticles

Small-sized bimetallic nanoparticles that possess numerous accessible metal sites and optimal geometric/electronic structures show great promise for advanced synergetic catalysis but remain synthetic challenge so far.Here,an universial synthetic method is developed for building a library of bimetallic nanoparticles on mesoporous sulfur-doped carbon supports,consisting of 24 combinations of 3 noble metals(that is,Pt,Rh,Ir)and 7 other metals,with average particle sizes ranging from 0.7 to 1.4 nm.The synthetic strategy is based on the strong metal-support interaction arising from the metal-sulfur bonding,which suppresses the metal aggregation during the H2-reduction at 700℃ and ensure the formation of small-sized and alloyed bimetallic nanoparticles.The enhanced catalytic properties of the ultrasmall bimetallic nanoparticles are demonstrated in the dehydrogenation of propane at high temperature and oxidative dehydrogenations of N-heterocycles.

Natural Nanofibrous Cellulose-Derived Solid Acid Catalysts

Solid acid catalysts(SACs)have attracted continuous research interest in past years as they play a pivotal role in establishing environmentally friendly and sustainable catalytic processes for various chemical industries.Development of low-cost and efcient SACs applicable to diferent catalysis processes are of immense signifcance but still very challenging so far.Here,we report a new kind of SACs consisting of sulfonated carbon nanofbers that are prepared via incomplete carbonization of low-cost natural nanofbrous cellulose followed by sulphonation with sulfuric acid.Te prepared SACs feature nanofbrous network structures,high specifc surface area,and abundant sulfonate as well as hydroxyl and carboxyl groups.Remarkably,the nanofbrous SACs exhibit superior performance to the state-of-the-art SACs for a wide range of acid-catalyzed reactions,including dimerization of�-methylstyrene,esterifcation of oleic acid,and pinacol rearrangement.Te present approach holds great promise for developing new families of economic but efcient SACs based on natural precursors via scalable and sustainable protocols in the future.

Intermetallic IrGa-IrO_(x) core-shell electrocatalysts for oxygen evolution Hide Author's Information

The development of high-performance Ir-based catalyst for electrocatalysis of oxygen evolution reaction(OER)in acidic media plays a critical role in realizing the commercialization of polymer electrolyte membrane-based water electrolyzer technology.Here we report a low-Ir core–shell OER electrocatalyst consisting of an intermetallic IrGa(IrGa-IMC)core and a partially oxidized Ir(IrOx)shell.In acidic electrolytes,the IrGa-IMC@IrOx core–shell catalysts exhibit a low overpotential of 272 mV at 10 mA·cm^(−2) with Ir loading of~20µg·cm^(−2) and a mass activity of 841 A·gIr^(−1) at 1.52 V,which is 3.6 times greater than that of commercial Ir/C(232 A·gIr^(−1))catalyst.We understand by the density functional theory(DFT)calculations that the enhanced OER activity of the IrGa-IMC@IrO_(x) catalysts is ascribed to the lifted degeneracy of Ir 5d electron of surface IrO_(x) sites induced by the intermetallic IrGa core,which increases the adsorption capacity of IrO_(x) layer for O and OH binding and eventually lowers the energy barrier of the OER rate-determining steps.

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.

Building the bridge of small organic molecules to porous carbons via ionic solid principle

Replacing traditional polymer-based precursors with small molecules is a promising pathway toward facile and controllable preparation of porous carbons but remains a prohibitive challenge because of the high volatility of small molecules.Herein,a simple,general,and controllable method is reported to prepare porous carbons by converting small organic molecules into organic molecular salts followed by pyrolysis.The robust electrostatic force holding organic molecular salts together leads to negligible volatility and thus ensures the formation of carbons under high-temperature pyrolysis.Meanwhile,metal moieties in organic molecular salts can be evolved into in-situ templates or activators during pyrolysis to create nanopores.The modular nature of organic molecular salts allows easy control of the porosity and chemical doping of carbons at a molecular level.The sulfur-doped carbon prepared by the ionic solid strategy can serve as robust support to prepare small-sized intermetallic PtCo catalysts,which exhibit a high mass activity of 1.62 A·mgPt^(−1)in catalyzing oxygen reduction reaction for fuel cell applications.

Intermetallic PdCd Core Promoting CO Tolerance of Pd Shell for Electrocatalytic Formic Acid Oxidation

Liquid fed fuel cells such as direct formic acid fuel cells(DFAFCs)are considered to be promising power sources for portable electronic devices.However,the poison of CO intermediates on the state-of-the-art platinum and palladium-based electrocatalysts for the formic acid oxidation reaction(FAOR)at the anode hampers the implementation of DFAFCs technologies.Here,we report a core/shell catalyst consisting of intermetallic PdCd core and Pd shell(i-PdCd@Pd)with promoted CO anti-poison ability and thus FAOR performance.The optimal i-PdCd@Pd catalyst exhibits a high mass activity and specific activity at peak potential,which are 24 and 4 times greater than that of commercial Pd/C catalyst,respectively.We understand by in-situ surface-enhanced infrared absorption spectroscopy(ATR-SEIRA)and X-ray photoelectron spectroscopy(XPS)that in i-PdCd@Pd,the intermetallic PdCd under-layers can induce the downshift of d-band center of surface Pd atoms,which would improve the CO tolerance and thus promote the FAOR performance.