Easy preparation of multifunctional ternary PdNiP/C catalysts toward enhanced small organic molecule electro-oxidation and hydrogen evolution reactions

The small organic molecule electro-oxidation(OMEO) and the hydrogen evolution(HER) are two important half-reactions in direct liquid fuel cells(DLFCs) and water electrolyzers,respectively,whose performance is largely hindered by the low activity and poor stability of electrocatalysts.Herein,we demonstrate that a simple phosphorization treatment of commercially available palladium-nickel(PdNi) catalysts results in multifunctional ternary palladium nickel phosphide(PdNiP) catalysts,which exhibit substantially enhanced electrocatalytic activity and stability for HER and OMEO of a number of molecules including formic acid,methanol,ethanol,and ethylene glycol,in acidic and/or alkaline media.The improved performance results from the modification of electronic structure of palladium and nickel by the introduced phosphorus and the enhanced corrosion resistance of PdNiP.The simple phosphorization approach reported here allows for mass production of highly-active OMEO and HER electrocatalysts,holding substantial promise for their large-scale application in direct liquid fuel cells and water electrolyzers.

3D Interconnected Honeycomb‑Like Multifunctional Catalyst for Zn-Air Batteries

Developing high-performance and low-cost electrocatalysts is key to achieve the clean-energy target.Herein,a dual regulation method is proposed to prepare a 3D honeycomb-like carbon-based catalyst with stable Fe/Co co-dopants.Fe atoms are highly dispersed and fixed to the polymer microsphere,followed by a high-temperature decomposition,for the generation of carbon-based catalyst with a honeycomb-like structure.The as-prepared catalyst contains a large number of Fe/Co nanoparticles(Fe/Co NPs),providing the excellent catalytic activity and durability in oxygen reduction reaction,oxygen evolution reaction and hydrogen evolution reaction.The Zn-air battery assembled by the as-prepared catalyst as air cathode shows a good charge and discharge capacity,and it exhibits an ultra-long service life by maintaining a stable charge and discharge platform for a 311-h cycle.Further X-ray absorption fine structure characterization and density functional theory calculation confirms that the Fe doping optimizes the intermediate adsorption process and electron transfer of Co.

A-Site Effect on the Conversion of Bio-Ethanol into Isobutene over Ternary A1ZnyZrzOn Catalysts

Ternary multifunctional A1ZnyZrzOn catalysts are prepared by introducing A-site transition metals with the redox capability into binary Zn1Zr8On. Structure and morphology were investigated by means of XRD, BET and FESEM, respectively. Activity data showed that Cr addition exhibited obvious beneficial effect to promote isobutene production from direct conversion of bio-ethanol compared to other A-site metal dopants. A significant higher yield of isobutene over Cr-promoted Zn1Zr8On catalyst was also observed with respect to its binary Zn1Zr8On counterpart. The choice of A-site metal is of prime importance in the isobutene production, catalyzing mainly the ethanol dehydrogenation, meanwhile the appropriate addition of zinc on the catalyst surface is also essential for good isobutene yield.

In situ construction of Co/N/C-based heterojunction on biomass-derived hierarchical porous carbon with stable active sites using a Co-N protective strategy for high-efficiency ORR,OER and HER trifunctional electrocatalysts

The facile designs and fabrication of noble metal-free electrocatalysts are highly required to achieve multifunctional catalytic activity with excellent stability in Zn-air batteries,fuel cells and water splitting systems.Herein,a heterostructure engineering is applied to construct the high performance Co,Ncontaining carbon-based multifunctional electrocatalysts with the feature of isotype(i.e.n-n type Co_(2)N_(0.67)-BHPC)and anisotype(i.e.p-n type Co_(2)O_(3)-BHPC)heterojunctions for ORR,OER and HER.The nn type Co_(2)N_(0.67)-BHPC,in which biomass(e.g.mushroom)-derived hierarchical porous carbon(BHPC)incorporated with nonstoichiometric active species Co_(2)N_(0.67),is fabricated by using an in situ protective strategy of macrocyclic central Co-N_(4) from CoTPP(5,10,15,20-tetrakis(phenyl)porphyrinato cobalt)precursor through the intermolecularπ-πinteractions between CoTPP and its metal-free analogue H_(2) TPP.Meanwhile,an unprotected strategy of macrocyclic central Co-N_(4) from CoTPP can afford the anisotype Co_(2)O_(3)-BHPC p-n heterojunction.The as-prepared n-n type Co_(2)N_(0.67)-BHPC heterojunction exhibited a higher density of Co-based active sites with outstanding stability and more efficient charge transfer at the isotype heterojunction interface in comparison with p-n type Co_(2)O_(3)-BHPC heterojunction.Consequently,for ORR,Co_(2)N_(0.67)-BHPC exhibits the more positive onset and half-wave potentials of 0.93 and 0.86 V vs.RHE,respectively,superior to those of the commercial 20 wt%Pt/C and most of Cobased catalysts reported so far.To drive a current density of 10 mA cm^(-2),Co_(2)N_(0.67)-BHPC also shows the lower overpotentials of 0.34 and 0.21 V vs.RHE for OER and HER,respectively.Furthermore,the Zn-air battery equipped with Co_(2)N_(0.67)-BHPC displays higher maximum power density(109 mW cm^(-2))and charge-discharge cycle stability.Interestingly,the anisotype heterojunction Co_(2)O_(3)-BHPC as trifunctional electrocatalyst reveals evidently photoelectrochemical enhancement compared with the photostable Co_(2)N_(0.67)-BHPC.That is to say,isotype heterojunction material(n-n type Co^(2)N_(0.67)-BHPC)is equipped with better electrocatalytic performance than anisotype one(p-n type Co_(2)O_(3)-BHPC),but the opposite is true in photoelectrochemical catalysis.Meanwhile,the possible mechanism is proposed based on the energy band structures of the Co_(2)N_(0.67)-BHPC and Co_(2)O_(3)-BHPC and the cocatalyst effects.The present work provides much more possibilities to tune the electrocatalytic and photoelectrochemical properties of catalysts through a facile combination of heterostructure engineering protocol and macrocyclic central metal protective strategy.

Engineering hollow core-shell hetero-structure box to induce interfacial charge modulation for promoting bidirectional sulfur conversion in lithium-sulfur batteries

Severe polysulfide shuttling and sluggish sulfur redox kinetics significantly decrease sulfur utilization and cycling stability in lithium-sulfur batteries(LSBs).Herein,we develop a hollow CoO/CoP-Box core-shell heterostructure as a model and multifunctional catalyst modified on separators to induce interfacial charge modulation and expose more active sites for promoting the adsorption and catalytic conversion ability of sulfur species.Theoretical and experimental findings verify that the in-situ formed core-shell hetero-interface induces the formation of P-Co-O binding and charge redistribution to activate surface O active sites for binding lithium polysulfides(LiPSs)via strong Li-O bonding,thus strongly adsorbing with Li PSs.Meanwhile,the strong Li-O bonding weakens the competing Li-S bonding in LiPSs or Li2S adsorbed on CoO/CoP-Box surface,plus the hollow heterostructure provides abundant active sites and fast electron/Li+transfer,so reducing Li2S nucleation/dissolution activation energy.As expected,LSBs with CoO/CoP-Box modified separator and traditional sulfur/carbon black cathode display a large initial capacity of 1240 mA h g^(-1)and a long cycling stability with 300 cycles(~60.1%capacity retention)at 0.5C.Impressively,the thick sulfur cathode(sulfur loading:5.2 mg cm^(-2))displays a high initial areal capacity of 6.9 mA h cm^(-2).This work verifies a deep mechanism understanding and an effective strategy to induce interfacial charge modulation and enhance active sites for designing efficient dual-directional Li-S catalysts via engineering hollow core-shell hetero-structure.

Multifunctional design of single-atom catalysts for multistep reactions

With the merits of high atom utilization,low cost,unique and tunable microstructures,as well as the particular catalytic behaviors,single-atom catalysts(SACs)have gained worldwide interest and achieved great advancements in heterogeneous catalysis recently.However,catalyzing an intricate multistep reaction is usually challenging for one single-atom center,in which case multiple catalytic sites are needed.In this review,the experimental and computational advances in the construction strategies of multi-active-site SACs will be summarized and classified as single-atom/single-atom,single-atom/nanoparticle and single-atom/support multifunctional catalysts.The microstructures of different active centers and their catalytic behaviors during catalysis will be emphatically highlighted.Moreover,the confronting challenges and opportunities of this field will be discussed.This review will place emphasis on the design of multifunctional SACs for multistep reactions,which will shed light on their further development in heterogeneous catalysis and beyond.

Multifunctional catalytic activity of Cu 3 N(001)surface:A first-principles study

Multifunctional catalysts that exhibit high catalytic performance for the hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and oxygen reduction reaction(ORR)in a single material hold great promise for broad-spectrum applications,including overall water splitting,fuel cells,and metal-air batteries.In this first-principles study,Cu_(3) N is computationally demonstrated as a multifunctional electrocatalyst for the HER,OER,and ORR owing to the unique coordination of N and Cu atoms on the(001)surface.Cu_(3) N exhibits better HER catalytic activity than noble Pt-based catalysts.Furthermore,its OER and ORR catalytic activity is comparable to that of commercialized unifunctional catalysts,and its 4e-pathway selectivity is high during the ORR.The catalytic performance of the ORR is significantly improved by the introduction of vacancy defects.The integration of highly efficient HER,OER,and ORR catalytic performance in earth-abundant Cu_(3) N not only opens an avenue for developing cost-efficient omnipotent catalysts but also facilitates advances in clean and renewable energy.

Biomass-assisted approach for large-scale construction ofmulti-functional isolated single-atom site catalysts

In recent years,the isolated single-atom site(ISAS)catalysts have attracted much attention as they are cost-effective,can achieve 100%atom-utilization efficiency,and often display superior catalytic performance.Here,we developed a biomass-assisted pyrolysis-etching-activation(PEA)strategy to construct ISAS metal decorated on N and B co-doped porous carbon(ISAS M/NBPC,M=Co,Fe,or Ni)catalysts.This PEA strategy can be applied in the universal and large-scale preparation of ISAS catalysts.Interestingly,the ISAS M/NBPC(M=Co,Fe,or Ni)catalysts show multi-functional features and excellent catalytic activities.They can be used to conduct different types of catalytic reactions,such as O-silylation(OSI),oxidative dehydrogenation(ODH),and transfer hydrogenation(THG).In addition,we used the transfer hydrogenation of nitrobenzene as a typical reaction and revealed the difference between ISAS Co/NBPC and ISAS Co/NPC(N-doped porous carbon)catalysts by density functional theory(DFT)calculations,and which showed that the decreased barrier of the ratedetermining step and the low-lying potential energy diagram indicate that the catalytic activity is higher when ISAS Co/NBPC is used than that when ISAS Co/NPC is used.These results demonstrate that the catalytic performance can be effectively improved by adjusting the coordination environment around the ISAS.