Surface-tailored PtPdCu ultrathin nanowires as advanced electrocatalysts for ethanol oxidation and oxygen reduction reaction in direct ethanol fuel cell

The development of advanced electrocatalysts for efficient catalyzing ethanol oxidation reaction(EOR)and oxygen reduction reaction(ORR) is significant for direct ethanol fuel cells(DEFCs).However,in many previous studies,the major difficulties including lower utilization efficiency and weaker anti-CO-poison ability of Pt hamper the practical testing of such DEFCs,Herein,ternary Pt22Pd27C51 ultrathin(~5 nm)NWs are fabricated via a facile surfactant-free strategy.The surface and electronic structures of Pt22Pd27Cu51 NWs are further tailored via acid-etching treatment.The resulted PtPdCu NWs with an optimal atomic Pt/Pd/Cu ratio of 36:41:23 display excellent specific activities towards EOR(4.38 mA/cm^(2))and ORR(1.16 mA/cm^(2)),which are 19.8-and 5.7-folds larger than that of Pt/C,respectively.A singlecell was fabricated using Pt36Pd41Cu23 NWs as electrocatalyst in both anode and cathode with Pt loading of 1.2 mgpt/cm^(2).The power density measured at 80 ℃ is 21.7 mW/cm^(2),which is ~3.9 folds enhancement relative to that fabricated by using Pt/C(2 mgPt/cm^(2)).The enhanced catalytic performance of Pt36Pd41Cu23NWs could be attributed to that synergistic effect between Pt,Pd and Cu enhances CO anti-poisoning ability and promotes the C-C bond cleavage.This work provides a promising strategy for developing efficient electrocatalysts for DEFCs.

Antifungal effects of BiOBr nanosheets carrying surfactant cetyltrimethylammonium bromide

BiOBr nanosheets are important photocatalytic nanomaterials. However, their biological effects remain to be explored. In this study, we investigated the antifungal effect of BiOBr nanosheets on Candida albicans. Strikingly,the nanosheets strongly inhibited the growth of C. albicans [IC50=（96±4.7） mg/L],hyphal development and biofilm formation. Compareed to the antifungal effect of the cationic surfactant cetyltrimethylammonium bromide, the inhibitory effect of the nanosheets on fungal pathogen was attributed to cetyltrimethylammonium bromide adsorbed by the nanosheets. Thermal gravity analysis and cetyltrimethylammonium bromide release experiment indicated that only 0.42% cetyltrimethylammonium bromide on BiOBr nanosheets was released. Taken together, this study uncovers the contribution of surfactant released from the nanosheets to their antifungal activity.

Recent advances in the electrocatalytic oxidative upgrading of lignocellulosic biomass

Lignocellulosic biomass is a critical renewable carbon resource,but most of its utilization is inefficient,and elec-trocatalytic oxidation is a promising method of upgrading lignocellulose into value-added fuels and chemicals under mild operating conditions.Recently,efforts to enable conversion with a high efficiency and low energy con-sumption have been reported,but understanding the reaction mechanisms and realizing scaled-up applications of the electrooxidation of lignocellulosic biomass are still in their early stages.A timely overview of recently reported general reaction mechanisms,particularly the strategies developed for use in improving the reaction efficiencies,is necessary to inspire research regarding the highly efficient utilization of lignocellulose.Herein,we summa-rize the strategies developed to improve electrocatalytic performance in oxidative lignocellulose conversion.The organized summary includes strategies ranging from designing efficient electrocatalysts and adding functional co-catalysts or electrolytes to employing advanced electrolyzers.A comprehensive overview of representative examples should provide universal principles to yield insight into the reaction processes and guide the design of efficient electrocatalytic systems.Finally,the challenges and opportunities in developing the electrocatalytic oxidative upgrading of lignocellulosic biomass in the near future are proposed.

Porous-hollow nanorods constructed from alternate intercalation of carbon and MoS2 monolayers for lithium and sodium storage

Weak ion diffusion and electron transport due to limited interlayer spacing and poor electrical conductivity have been identified as critical roadbacks for fast and abundant energy storage of both MoS2-based lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In this work, MoS2 porous-hollow nanorods (MoS2/m-C800) have been designed and synthesized via an annealing-followed chemistry-intercalated strategy to solve the two issues. They are uniformly assembled from ultrathin MoS2 nanosheets, deviated to the rod-axis direction, with expanded interlayer spacing due to alternate intercalation of N-doped carbon monolayers between the adjacent MoS2 monolayers. Electrochemical studies of the MoS2/m-C800 sample, as an anode of LIBs, demonstrate that the superstructure can deliver a reversible discharge capacity of 1,170 mAh·g^-1 after 100 cycles at 0.2 A·g^-1 and maintain a reversible capacity of 951 mAh·g^-1 at 1.25 A·g^-1 after 350 cycles. While for SIBs, the superstructure also delivers a reversible discharge capacity of 350 mAh·g^-1 at 0.5 A-g-1 after 500 cycles and exhibits superior rate capacity of 238 mAh·g^-1 at 15 A·g^-1 .The excellent electrochemical performance is closely related with the hierarchical superstructures, including expanded interlayer spacing, alternate intercalation of carbon monolayers and mesoporous feature, which effectively reduce ion diffusion barrier, shorten ion diffusion paths and improve electrical conductivity.

Fabrication of N,S co-doped carbon immobilized high-density Co single atoms toward electro-oxidation of organic sulfides with water as feedstock

Development of high-density single atoms site(SAs)electrocatalysts is highly desirable due to their extraordinary catalytic performance.However,their synthesis is still challenging and their anticorrosion capacities in electrolyte(particularly in acidic electrolyte)are unsatisfying.Herein,we have constructed N,S co-doped carbon to anchor~10 wt.%Co SAs(Co-SAs/NSC)via a novel polymerization–sulfurization–pyrolysis strategy toward selective electro-oxidation of thioethers in acidic solution.The asobtained Co SAs has a coordination geometry of Co-S_(2)N_(4),exhibiting excellent electrocatalytic activity and robust stability.At a low potential of 1.40 V vs.reversible hydrogen electrode(RHE),the conversion rate of thioethers over Co-SAs/NSC reaches 99.7%with 100%selectivity and 100%Faraday efficiency(FE)for producing sulfoxide,which is higher than the commercial Pt electrode and the reported state-of-the-art catalysts.Theoretical calculations and experiments reveal that the Co-S_(2)N_(4)structure endows the outstanding electro-oxidation activity of Co SAs through significantly promoting desorption of the products.This work presents a convenient strategy to build high-performance SAs catalysts for the resourceful use of sulfur-containing pollutants.

Size-effect on Ni electrocatalyst:The case of electrochemical benzyl alcohol oxidation

The nanoparticles(NPs)of Ni with different sizes endows its distinctive physical and chemical properties,which represents a typical strategy for the development of high-performance catalysts.However,the size effect of metallic Ni-NPs on electrocatalytic performance remains ambiguous.Herein,the Ni-NPs with different sizes supported on nitrogen doped carbon(NC)has been synthesized by controlling the pyrolysis temperature,leading to the synthesis of Ni@NC-500(8.3 nm),Ni@NC-280(1.9 nm)and Ni@NC-200(1.0 nm).The electrooxidation of benzyl alcohol(BA)over these nanocatalysts shows the yield of benzoic acid was 99%,82%,55%on Ni@NC-280,Ni@NC-200 and Ni@NC-500,respectively.The experimental and theoretical simulation demonstrate that the difference in the adsorption strength of reactant molecules by Ni-NPs is responsible for their different performance,where the Ni@NC-280 exhibits an optimal adsorption configuration between Ni@NC-280 electrode and BA.This work provides a new angle for designing and synthesizing efficient electrocatalysts,which may be extended to the exploration of various promising electrocatalytic systems.

An integrated cathode with bi-functional catalytic effect for excellent-performance lithium-sulfur batteries

The high energy density of lithium-sulfur batteries (LSBs) is mainly based on the complex redox reactions and phase conversions.The sluggish redox kinetics and the large accumulation of soluble polysulfides in the electrolyte leads to low sulfur utilization and serious shuttle effect.Herein,an integrated sulfur cathode is constructed through a facile and large-scale method.It is composed of sulfur-N,S doped bamboo like CNTs@Co3S4 (NSC@Co3S4) composites on polypropylene separator.The immobilized polysulfides on the NSC@Co3S4 surface are further reduced/oxidized during the discharge/charge process via the efficient bi-functional catalytic effect of NSC@Co3S4,resulting in the rapid conversion of LiPSs.Consequently,the integrated sulfur cathode delivers a high initial reversible capacity of 1,473.6 mAh·g^-1 at 0.2 C and a high specific capacity of 979 mAh·g^-1 at 1 C after 500 cycles as well as excellent cycling stability for 1,000 cycles with a high specific capacity of 362.5 mAh·g^-1 at 5 C,which are superior to reported similar host materials.

In situ preparation of gel polymer electrolyte for lithium batteries: Progress and perspectives

The practical applications of Li-ion batteries(LIBs)are challenged by their safety concerns when using liquid electrolytes(LEs).Solid-state gel polymer electrolytes(GPEs)can address this challenge and have drawn increased attention recently.Normally,GPEs are prepared separately and then assembled into cells,which undoubtedly result in dissatisfactory solid/solid interfacial compatibility and low ionic conductivity.Fortunately,in situ GPEs are proposed to address the above challenges and simplify the preparation process.Typically,LE precursor is injected into the cells and gradually transformed into a quasisolid gel state under the conditions of thermal or chemical initiators.Consequently,the obtained in situ GPEs could fully infiltrate the electrode and better interface contact of gel electrolyte/electrode is thus inherited.In this review,the authors focus on the in situ GPEs used in lithium batteries(LBs),and summarize recent progress of the design,synthesis,and applications of in situ GPEs.Based on the different ways of triggering polymerization,there are mainly three methods:thermochemical gelation,polymerization by additional chemical initiators,and cross-linking initiated by Li O bond.Composite GPEs based on in situ solidification method are introduced as a promising strategy to improve the electrochemical performances.Finally,up-to-date research progresses are discussed,and perspectives are provided on the development and challenges of in situ GPEs to meet the requirements for their practical applications in LBs.

V-doped Ni_(3)N/Ni heterostructure with engineered interfaces as a bifunctional hydrogen electrocatalyst in alkaline solution:Simultaneously improving water dissociation and hydrogen adsorption

Alkali-water electrolyzers and hydroxide exchange membrane fuel cells are emerging as promising technologies to realize hydrogen economy.Developing cost-effective electrode materials with high activities towards corresponding hydrogen evolution(HER)and oxidation(HOR)reactions plays a crucial role in commercial hydrogen production and utilization.Herein,we fabricated a V-doped Ni_(3)N/Ni heterostructure(V-Ni_(3)N/Ni)through a controlled nitridation treatment on a V-incorporated nickel hydroxide precursor.The resultant catalyst exhibits comparable catalytic activity and durability to commercial Pt/C in terms of both HER(a low overpotential of 44 mV at the current density of 10 mA·cm^(-2))and HOR(a high current density of 1.54 mA·cm^(-2)at 0.1 V versus reversible hydrogen electrode)under alkaline conditions.The superior activity of V-Ni_(3)N/Ni grown on different substrates further implies its intrinsic performance.Density functional theory(DFT)calculations reveal that the coupled metallic Ni and doped V can promote the water adsorption,accelerate the Volmer step of alkaline HER,as well as optimize the adsorption and desorption of hydrogen intermediate(H^(*))to reach a balancedΔGH*value.

Ultrathin nanoporous metal electrodes facilitate high proton conduction for low-Pt PEMFCs

Design of catalyst layers(CLs)with high proton conductivity in membrane electrode assemblies(MEAs)is an important issue for proton exchange membrane fuel cells(PEMFCs).Herein,an ultrathin catalyst layer was constructed based on Pt-decorated nanoporous gold(NPG-Pt)with sub-Debye-length thickness for proton transfer.In the absence of ionomer incorporation in the CLs,these integrated carbon-free electrodes can deliver maximum mass-specific power density of 198.21 and 25.91 kW·gPt^(-1) when serving individually as the anode and cathode,at a Pt loading of 5.6 and 22.0 pg·cm^(-2),respectively,comparable to the best reported nano-catalysts for PEMFCs.In-depth quantitative experimental measurements and finite-element analyses indicate that improved proton conduction plays a critical role in activation,ohmic and mass transfer polarizations.

Highly coordinated Pd overlayers on nanoporous gold for efficient formic acid electro-oxidation

Design and fabrication of highly efficient and stable electrocatalysts remain key challenges in green energy technologies such as low-temperature direct liquid fuel cells.Based on in-depth theoretical calculations,here we demonstrate that surface Pd atoms with high coordination numbers(HCNs)can effectively modulate their adsorption energies for CO and OH,and thus achieve very high performance for formic acid electro-oxidation reaction(FAOR).Based on epitaxial coating Pd atomic layers onto nanoporous gold(NPG)thin membranes and a slight further decoration of Au clusters on top,the resulted core-shell structured NPG-Pd-Au electrocatalyst can demonstrate Pd intrinsic and mass activities of 8.62 mA·cm^(-2)and 27.25 A·mg^(-1)respectively at the peak potential around 0.33 V versus saturated calomel electrode toward FAOR,which are far better than those of commercial Pd/C catalysts(1.09 mA·cm^(-2)and 0.32 A·mg^(-1))tested under the same conditions.Moreover,the membrane electrode assemblies based on these low precious metal loading electrodes can achieve an anode Pd power efficiency over 10 W·mg^(-1)in a direct formic acid fuel cell,which is two orders of magnitude higher than that of the commercial Pd/C.These results provide new inspirations for the development of revolutionary electrodes for energy technologies in a rational manner.

Co/N-doped carbon nanotube arrays grown on 2D MOFs-derived matrix for boosting the oxygen reduction reaction in alkaline and acidic media

The development of high-performance and cost-effective electrocatalysts towards oxygen reduction reaction(ORR) is of significant importance,but still challenging for the practical applications in related energy systems.ORR process typically suffers from sluggish kinetics,the exploration of ORR electrocatalyst thus requires elaborate design.Herein,an effective strategy is developed for growing Co/N-doped carbon nanotube arrays on 2D MOFs-derived matrix via the pyrolysis of Co/Zn metalorganic-framework(MOF) nanosheets.The Co/Zn-MOF nanosheets serve as both the self-template for the 2D carbonized framework morphology and C/N source for the in-situ growth of 1D N-doped carbon nanotubes.The constructed hie rarchical architecture effectively integrates the OD/1D Co nanoparticle/Ndoped carbon nanotube interface and 1D(nanotubes)/2D(nanosheets) junction into frameworks with highly exposed active surface,enhanced mass-transport kinetics and electrical conductivity.As a result,the designed composite exhibits superior ORR activity and durability in alkaline media as compared to commercial Pt/C.Particularly,it shows promising ORR performance with a half-wave potential of 0.78 V versus reversible hydrogen electrode and negligible activity attenuation after 5000 potential cycles in acidic electrolyte.The designed strategy can be extended to construct other MOFs-derived carbon matrixes with diverse hierarchical structures and provide an efficient avenue for searching highperformance electrocatalysts.

In situ decomposition of metal-organic frameworks into ultrathin nanosheets for the oxygen evolution reaction

The oxygen evolution reaction （OER） is a pivotal process for water-splitting and many other energy technologies involving oxygen electrodes. Herein, a new synthesis strategy is proposed to prepare OER catalysts based on a simple yet flexible in situ decomposition of Co-based acetate hydroxide metal-organic frameworks （MOFs）. This process allows straightforward fabrication of various 2D hydroxide ultrathin nanosheets （UNSs） with excellent component controllability. The as-obtained Co-based hydroxide UNSs demonstrate superior catalytic activity for the OER due to the exposure of numerous active sites. In particular, the CoNi hydroxide UNSs exhibit low overpotentials （r/） of 324 and 372 mV at current densities of 10 and 100 mA-cm-2, respectively; a large turnover frequency （TOF） of 0.16 s-~ at T/= 380 mV; and a small Tafel slope of 33 mV.dec-~ in an alkaline environment. Importantly, these values are superior to those of the state-of-the- art IrO2 commercial electrocatalyst. This facile strategy enables the exploration of more efficient and economic OER electrocatalysts with various constituents and opens a promising avenue for large-scale fabrication of functional nanocatalysts for use in clean ener~：v technologies.

Seed-mediated Growth of Alloyed Ag-Pd Shells toward Alkyne Semi-hydrogenation Reactions under Mild Conditions

Ag@Ag-Pdx core-shell nanocomposites with various Ag/Pd ratio were deposited on Ag nanoplates using a seed growth method.When physically loaded on C3N4,Ag@Ag-Pd0.077/C3N4 with optimized Ag/Pd ratio could accomplish high catalytic performance for the semi-hydrogenation of phenylacetylene as well as other aliphatic(both terminal and internal alkynes)alkynes and phenylcycloalkynes containing functional groups(such as ester,hydroxyl,ethyl groups)under room temperature and 1 atm H_(2).The alloying and ensemble effects are used to interpret such catalytic performance.

Nanoscratching and mechanical behaviors of high-entropy alloys with different phase constituents

High-entropy alloys(HEAs)exhibit unique microstructural features and properties in nanoscale and atomic scale because of their multi-element alloy system.The nanoscratching behaviors of three HEAs with different phase constituents,relative to the microstructure and mechanical properties of the HEAs,were investigated.Three typical phase constituents were selected:face-centered cubic(FCC)structure,body-centered cubic(BCC)structure,and a dual-phase structure containing both FCC and BCC phases.Despite the fact that the FCC alloy has the highest ductility and strain hardening capability,it exhibited inferior scratch resistance due to the over-softening of hardness.Due to the brittle failure mode,the BCC alloy hardly exhibited desirable scratch resistance despite its highest hardness.By contrast,the nanostructured dual-phase alloy exhibited the best scratch resistance because of its good combination of strength and ductility,as well as the ductile failure mode.This research suggests that the HEA with structure comprising nanoscale hard and soft phases is desirable for nanoscratch resistance,and possesses appropriate hardness for industrial applications.

Erratum to:V-doped Ni_(3)N/Ni heterostructure with engineered interfaces as a bifunctional hydrogen electrocatalyst in alkaline solution:Simultaneously improving water dissociation and hydrogen adsorption

Erratum to Nano Research 2021,14(10):3489–3496 https://doi.org/10.1007/s12274-021-3559-9 In Acknowledgements,one of the foundation numbers of Tianjin Municipal Science and Technology Commission(No.18TCQNJC71500)was unfortunately mistakenly used.

Selectivity regulation of CO_(2)electroreduction on asymmetric AuAgCu tandem heterostructures

Rational design and synthesis of multimetallic nanostructures(NSs)are fundamentally important for electrochemical CO_(2)reduction reaction(CO_(2)RR).Herein,a multi-step seed-mediated growth method is applied to synthesize asymmetric AuAgCu heterostructures using Au nanobipyramids as nucleation seeds,in which their composition and structures are well controlled.We find that the selectivity of C_(2)products for CO_(2)RR could be effectively regulated by tandem catalysis and electronic effect over trimetallic AuAgCu heterostructures.Particularly,the Faraday efficiency toward ethanol could reach up to 37.5%at a potential of−0.8 V versus reversible hydrogen electrode over asymmetric Au1Ag1Cu5 heterostructures with segregated domains of three constituent metals.This work provides an efficient strategy for the synthesis of multicomponent architectures to boost their promising application in CO_(2)RR.

Ultrathin nanoporous metal-semiconductor heterojunction photoanodes for visible light hydrogen evolution

Plasmonic metal-semiconductor nano-heterojuncfions （NHJs）, with their superior photocatalytic performance, provide opportunities for the efficient utilization of solar energy. However, scientific significance and technical challenges remain in the development of suitable metal-semiconductor NHJ photoelectrodes for new generation flexible optoelectronic devices, which often require complex processing. Herein, we report integrated three-dimensional （3D） NHJ photoelectrodes by conformally coating cadmium sulfide （CdS） nanolayers onto ultrathin nano- porous gold （NPG） films via a facile electrodeposition method. Localized surface plasmon resonance （LSPR） of NPG enhances the electron-hole pair generation and separation. Moreover, the direct contact interface and high conductive framework structure of the NHJs boosts the photogenerated carrier separation and transport. Hence, the NHJs exhibit evidently enhanced photocurrent density and hydrogen evolution rate relative to CdS deposited on either gold （Au） foil or fluorine-doped tin oxide （FTO） at 0 V vs. SCE （saturated calomel electrode） under visible-light irradiation. Moreover, they demonstrate a surprisingly stable photoelectrochemical hydrogen evolution （PEC-HE） activity over 104 s of continuous irradiation.

Designing heterostructured FeP–CoP for oxygen evolution reaction:Interface engineering to enhance electrocatalytic performance

It is significant to develop highly efficient electrocatalysts for energy conversion systems.Interface engineering is one of the most feasible approaches to effectively enhance the electrocatalytic activity.Herein,the density functional theory(DFT)calculations predict that the potential barriers of Fe sites at the interface of FeP–CoP heterostructures are lower than that of Fe sites in FeP nanoparticles(NPs),Co sites in CoP NPs,or Co sites in heterostructures.Motivated by the DFT calculation results,FeP–CoP heterostructures have been designed and synthesized by a metal–organic frameworks(MOFs)confined-phosphorization method.The FeP–CoP exhibits the lowest overpotential of 230 mV at the current density of 10 mA·cm^(−2)for oxygen evolution reaction(OER),compared with FeP(470 mV)and CoP(340 mV),which outperforms most of transition metal-based catalysts.The Tafel analysis of FeP–CoP heterostructures shows an improved reaction kinetic pathway with the smallest slope of 90.3 mV·dec^(−1),as compared to the Tafel slopes of FeP NPs(137 mV·dec^(−1))and CoP NPs(114 mV·dec^(−1)).And the FeP–CoP shows extraordinary long-term stability over 24 h.The excellent activity and long-term stability of FeP–CoP derive from the synergistic effect between FeP and CoP.

原子分散的钪路易斯酸位点修饰氮化碳用于高效光催化合成过氧化氢

光催化氧还原制备过氧化氢具有节能、环保等优点.然而,低活性以及低选择性的问题限制了其实际应用.基于金属离子耦合电子转移机制,本文通过浸渍-煅烧法合成了原子分散的钪路易斯酸位点修饰的氮化碳,光合成过氧化氢速率高达55μmol h^(-1),是氮化碳的6.2倍.光催化性能的提升归因于原子分散钪路易斯酸位点与·O_(2)^(-)结合,提高了O_(2)的得电子能力,减少了·O_(2)^(-)逆反应的发生,促进了氧还原反应进行.密度泛函理论模拟及Koutecky-Levich分析表明,钪原子的引入减少了O–O键的断裂,提高了合成过氧化氢的选择性.本研究提出了一种路易斯酸单金属位点光催化剂设计新概念,可同时提升催化反应活性及选择性.