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Integrating air capture and conversion of CO 2 is key to realizing energy sustainability. However, current integration approaches require high temperature and pressure, making them energy intensive. Here, we demonstrate a nanoparticle (NP) catalysis approach for the hydrogenation of alkyl carbonate, an intermediate obtained from the CO 2 capture process, to formate, achieving one-pot air capture and conversion of CO 2 under ambient conditions. The capture is realized in an ethylene glycol (EG) solution of KOH (EG-KOH) at room temperature, where CO 2 is selectively converted into HO-CH 2 CH 2 -O-COOK (∼100% conversion). This carbonate is then hydrogenated using ammonia borane (under ambient pressure and at 50 °C) to formate (HCOOK) (>90% yield) in the presence of a stable Pd NP catalyst with EG being regenerated. Atomistic simulations suggest that the CO 2 absorption process in the EG-KOH solution is energetically stable, and the catalyst surface provides the reaction site to break the C-O bond in the -O-COOK structure, enabling the hydrogenation of the alkyl carbonate to formate and the regeneration of EG. Our study provides a promising NP-catalysis approach for air capture and conversion of CO 2 into value-added chemicals/fuels under ambient conditions.

Bolstered by their unique atomic structures and tailored compositions, nanoalloys exhibit extraordinary properties making them ideal materials to solve challenges in energy storage and conversion catalysis. However, a quantitative description of the structure-property relationships using an accurate descriptor-based model for nanoalloys, ranging from bimetallic to multimetallic compositions, is needed to drive efficient material design toward high-performance catalysis. In this work, we highlight the electronic property and catalytic activity relationship from an element specific d -band analysis of Pt-based alloy catalysts using X-ray absorption near-edge spectroscopy (XANES). Using a series of L1 0 -MPt/Pt (M = Fe, Co, Ni) core/shell alloy catalysts with well-defined atomic structures, we quantified subtle differences in the Pt d -electron states and correlated the Pt d -band structure to their superior catalytic activity toward the oxygen reduction reaction (ORR). Our analysis used the upper d -band edge position as a predictive descriptor for the mass activity toward the ORR instead of the commonly used d -band center position. Together with density functional theory calculations and Nørskov d -band theory, the upper d -band edge position for the Pt states, derived from experimental measurements, elucidates new physical insights into the ORR performance of the L1 0 -MPt/Pt core/shell catalysts. An element specific Pt d -band analysis using XANES overcomes challenges in traditional X-ray photoelectron spectroscopy-based valence d -band analysis, which cannot distinguish signals from independent elements in nanoalloys. Thus, the insights from the element specific d -band analysis presented in this work are a promising approach to determine structure-property relationships in a variety of transition metal nanoalloys and will be useful in the design of future high-performance catalysts.

We report a new design of polymer phenylacetylene (PA) ligands and the ligand exchange methodology for colloidal noble metal nanoparticles (NPs). PA-terminated poly(ethylene glycol) (PEG) can bind to metal NPs through acetylide (M-C≡C-R) that affords a high grafting density. The ligand-metal interaction can be switched between σ bonding and extended π backbonding by changing grafting conditions. The σ bonding of PEG-PA with NPs is strong and it can compete with other capping ligands including thiols, while the π backbonding is much weaker. The σ bonding is also demonstrated to improve the catalytic performance of Pd for ethanol oxidation and prevent surface absorption of the reaction intermediates. Those unique binding characteristics will enrich the toolbox in the control of colloidal surface chemistry and their applications using polymer ligands.

Uricase-catalyzed uric acid (UA) degradation has been applied for hyperuricemia therapy, but this medication is limited by H 2 O 2 accumulation, which can cause oxidative stress of cells, resulting in many other health issues. Herein, we report a robust cubic hollow nanocage (HNC) system based on polyvinylpyrrolidone-coated PdPt 3 and PdIr 3 to serve as highly efficient self-cascade uricase/peroxidase mimics to achieve the desired dual catalysis for both UA degradation and H 2 O 2 elimination. These HNCs have hollow cubic shape with average wall thickness of 1.5 nm, providing desired synergy to enhance catalyst's activity and stability. Density functional theory calculations suggest the PdIr 3 HNC surface tend to promote OH*/O* desorption for better peroxidase-like catalysis, while the PdPt 3 HNC surface accelerates the UA oxidation by facilitating O 2 -to-H 2 O 2 conversion. The dual catalysis power demonstrated by these HNCs in cell studies suggests their great potential as a new type of nanozyme for treating hyperuricemia.

Core@shell nanoparticles (NPs) have been widely explored to enhance catalysis due to the synergistic effects introduced by their nanoscale interface and surface structures. However, creating a catalytically functional core@shell structure is often a synthetic challenge due to the need to control the shell thickness. Here, we report a one-step synthetic approach to core-shell CuPd@Pd NPs with an intermetallic B2-CuPd core and a thin (∼0.6 nm) Pd shell. This core@shell structure shows enhanced activity toward selective hydrogenation of Ar-NO 2 and allows one-pot tandem hydrogenation of Ar-NO 2 to Ar-NH 2 and its condensation with Ar-CHO to form Ar-N═CH-Ar. DFT calculations indicate that the B2-CuPd core promotes the Pd shell binding to Ar-NO 2 more strongly than to Ar-CHO, thereby selectively activating Ar-NO 2 . The chemoselective catalysis demonstrated by B2-CuPd@Pd can be extended to a broader scope of substrates, allowing green chemistry synthesis of a wide range of functional chemicals and materials.

Efficient C-C bond cleavage and oxidation of alcohols to CO 2 is the key to developing highly efficient alcohol fuel cells for renewable energy applications. In this work, we report the synthesis of core/shell Au/Pt nanowires (NWs) with stepped Pt clusters deposited along the ultrathin (2.3 nm) stepped Au NWs as an active catalyst to effectively oxidize alcohols to CO 2 . The catalytic oxidation reaction is dependent on the Au/Pt ratios, and the Au 1.0 /Pt 0.2 NWs have the largest percentage (∼75%) of stepped Au/Pt sites and show the highest activity for ethanol electro-oxidation, reaching an unprecedented 196.9 A/mg Pt (32.5 A/mg Pt+Au ). This NW catalyst is also active in catalyzing the oxidation of other primary alcohols, such as methanol, n -propanol, and ethylene glycol. In situ X-ray absorption spectroscopy and infrared spectroscopy are used to characterize the catalyst structure and to identify key reaction intermediates, providing concrete evidence that the synergy between the low-coordinated Pt sites and the stepped Au NWs is essential to catalyze the alcohol oxidation reaction, which is further supported by DFT calculations that the C-C bond cleavage is indeed enhanced on the undercoordinated Pt-Au surface. Our study provides important evidence that a core/shell structure with stepped core/shell sites is essential to enhance electrochemical oxidation of alcohols and will also be central to understanding electro-oxidation reactions and to the future development of highly efficient direct alcohol fuel cells for renewable energy applications.

We report the use of polymer N -heterocyclic carbenes (NHCs) to control the microenvironment surrounding metal nanocatalysts, thereby enhancing their catalytic performance in CO 2 electroreduction. Three polymer NHC ligands were designed with different hydrophobicity: hydrophilic poly(ethylene oxide) (PEO-NHC), hydrophobic polystyrene (PS-NHC), and amphiphilic block copolymer (BCP) (PEO- b -PS-NHC). All three polymer NHCs exhibited enhanced reactivity of gold nanoparticles (AuNPs) during CO 2 electroreduction by suppressing proton reduction. Notably, the incorporation of hydrophobic PS segments in both PS-NHC and PEO- b -PS-NHC led to a twofold increase in the partial current density for CO formation, as compared to the hydrophilic PEO-NHC. While polymer ligands did not hinder ion diffusion, their hydrophobicity altered the localized hydrogen bonding structures of water. This was confirmed experimentally and theoretically through attenuated total reflectance surface-enhanced infrared absorption spectroscopy and molecular dynamics simulation, demonstrating improved CO 2 diffusion and subsequent reduction in the presence of hydrophobic polymers. Furthermore, NHCs exhibited reasonable stability under reductive conditions, preserving the structural integrity of AuNPs, unlike thiol-ended polymers. The combination of NHC binding motifs with hydrophobic polymers provides valuable insights into controlling the microenvironment of metal nanocatalysts, offering a bioinspired strategy for the design of artificial metalloenzymes., Competing Interests: The authors declare that they have no conflict of interest., (This journal is © The Royal Society of Chemistry.)

ConspectusFunctional nanoparticles (NPs) have been studied extensively in the past decades for their unique nanoscale properties and their promising applications in advanced nanosciences and nanotechnologies. One critical component of studying these NPs is to prepare monodisperse NPs so that their physical and chemical properties can be tuned and optimized. Solution phase reactions have provided the most reliable processes for fabricating such monodisperse NPs in which metal-ligand interactions play essential roles in the synthetic controls. These interactions are also key to stabilizing the preformed NPs for them to show the desired electronic, magnetic, photonic, and catalytic properties. In this Account, we summarize some representative organic bipolar ligands that have recently been explored to control NP formation and NP functions. These include aliphatic acids, alkylphosphonic acids, alkylamines, alkylphosphines, and alkylthiols. This ligand group covers metal-ligand interactions via covalent, coordination, and electrostatic bonds that are most commonly employed to control NP sizes, compositions, shapes, and properties. The metal-ligand bonding effects on NP nucleation rate and growth can now be more thoroughly investigated by in situ spectroscopic and theoretical studies. In general, to obtain the desired NP size and monodispersity requires rational control of the metal/ligand ratios, concentrations, and reaction temperatures in the synthetic solutions. In addition, for multicomponent NPs, the binding strength of ligands to various metal surfaces needs to be considered in order to prepare these NPs with predesigned compositions. The selective ligand binding onto certain facets of NPs is also key to anisotropic growth of NPs, as demonstrated in the synthesis of one-dimensional nanorods and nanowires. The effects of metal-ligand interactions on NP functions are discussed in two aspects, electrochemical catalysis for CO 2 reduction and electronic transport across NP assemblies. We first highlight recent advances in using surface ligands to promote the electrochemical reduction of CO 2 . Several mechanisms are discussed, including the modification of the catalyst surface environment, electron transfer through the metal-organic interface, and stabilization of the CO 2 reduction intermediates, all of which facilitate selective CO 2 reduction. These strategies lead to better understanding of molecular level control of catalysis for further catalyst optimization. Metal-ligand interaction in magnetic NPs can also be used to control tunneling magnetoresistance properties across NPs in NP assemblies by tuning NP interparticle spacing and surface spin polarization. In all, metal-ligand interactions have yielded particularly promising directions for tuning CO 2 reduction selectivity and for optimizing nanoelectronics, and the concepts can certainly be extended to rationalize NP engineering at atomic/molecular precision for the fabrication of sensitive functional devices that will be critical for many nanotechnological applications.

Anisotropy is an important and widely present characteristic of materials that provides desired direction-dependent properties. In particular, the introduction of anisotropy into magnetic nanoparticles (MNPs) has become an effective method to obtain new characteristics and functions that are critical for many applications. In this review, we first discuss anisotropy-dependent ferromagnetic properties, ranging from intrinsic magnetocrystalline anisotropy to extrinsic shape and surface anisotropy, and their effects on the magnetic properties. We further summarize the syntheses of monodisperse MNPs with the desired control over the NP dimensions, shapes, compositions, and structures. These controlled syntheses of MNPs allow their magnetism to be finely tuned for many applications. We discuss the potential applications of these MNPs in biomedicine, magnetic recording, magnetotransport, permanent magnets, and catalysis.

Nanostructured metal-nitrides have attracted tremendous interest as a new generation of catalysts for electroreduction of CO 2 , but these structures have limited activity and stability in the reduction condition. Herein, we report a method of fabricating FeN/Fe 3 N nanoparticles with FeN/Fe 3 N interface exposed on the NP surface for efficient electrochemical CO 2 reduction reaction (CO 2 RR). The FeN/Fe 3 N interface is populated with Fe-N 4 and Fe-N 2 coordination sites respectively that show the desired catalysis synergy to enhance the reduction of CO 2 to CO. The CO Faraday efficiency reaches 98% at -0.4 V vs. reversible hydrogen electrode, and the FE stays stable from -0.4 to -0.9 V during the 100 h electrolysis time period. This FeN/Fe 3 N synergy arises from electron transfer from Fe 3 N to FeN and the preferred CO 2 adsorption and reduction to *COOH on FeN. Our study demonstrates a reliable interface control strategy to improve catalytic efficiency of the Fe-N structure for CO 2 RR., (© 2023. The Author(s).)

Support vector machine (SVM) is a new machine learning method developed from statistical learning theory. Since the objective function of the unconstrained SVM model is a non-smooth function, a lot of fast optimization algorithms can't be used to find the solution. Firstly, to overcome the non-smooth property of this model, a new padé33 approximation smooth function is constructed by rational approximation method, and a new smooth support vector machine model (SSVM) is established based on the smooth function. Then, by analyzing the performance of the smooth function, we find that the smooth precision is significantly higher than existing smooth functions. Moreover, theoretical and rigorous mathematical analyses are given to prove the convergence of the new model. Finally, it is applied to the heart disease diagnosis. The results show that the Padé33-SSVM model has better classification capability than existing SSVMs., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Wang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Due to the wide application of wearable electronic devices in daily life, research into flexible electronics has become very attractive. Recently, various polymer-based sensors have emerged with great sensing performance and excellent extensibility. It is well known that different structural designs each confer their own unique, great impacts on the properties of materials. For polymer-based pressure/strain sensors, different structural designs determine different response-sensing mechanisms, thus showing their unique advantages and characteristics. This paper mainly focuses on polymer-based pressure-sensing materials applied in different microstructures and reviews their respective advantages. At the same time, polymer-based pressure sensors with different microstructures, including with respect to their working mechanisms, key parameters, and relevant operating ranges, are discussed in detail. According to the summary of its performance and mechanisms, different morphologies of microstructures can be designed for a sensor according to its performance characteristics and application scenario requirements, and the optimal structure can be adjusted by weighing and comparing sensor performances for the future. Finally, a conclusion and future perspectives are described.

Polymer N -heterocyclic carbenes (NHCs) are a class of robust surface ligands to provide superior colloidal stability for metal nanoparticles (NPs) under various harsh conditions. We report a general method to prepare polymeric NHCs and demonstrate that these polymer NHC-AgNPs are stable against oxidative etching and show high peroxidase activity. We prepared three imidazolium-terminated poly(methyl methacrylate) (PMMA), polystyrene (PS), and poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO 2 MA) through atom-transfer radical polymerization with an imidazole-containing initiator. The imidazolium end group was further converted to NHC-Ag(I) in the presence of Ag 2 O at room temperature. Polymer NHC-Ag(I) can transmetalate to AgNPs through ligand exchange at the interface of oil/water within 2 min. All the three polymers can modify metal NPs, such as AgNPs, Ag nanowires, and AuNPs, providing excellent thermal, oxidative, and chemical stabilities for AgNPs. As an example, in the presence of hydrogen peroxide, AgNPs modified by polymer NHCs were resistant against oxidative etching with a rate of ∼700 times slower than those grafted with thiolates. AgNPs modified by polymer NHCs also showed higher peroxidase activity, 4 times more active than those capped by citrate and polyvinylpyrrolidone (PVP) and 2 times more active than those with polymer thiolate. Our studies demonstrate a great potential of using polymer NHCs to stabilize metallic NPs for various applications.

Introduction: This paper explores consumers' coping strategies when they feel negative emotions due to forced deconsumption during the Covid-19 pandemic lockdowns., Methods: The tool used for data collection is the questionnaire. It was made using the LimeSurvey software. A total of 621 complete observations were analyzed., Results: The findings demonstrate that anger positively influences the activation of seeking social support, mental disengagement, and confrontive coping strategies. Besides, disappointment activates mental disengagement but only marginally confrontive coping and not behavioral disengagement. Furthermore, regret is positively related to confrontive coping, behavioral disengagement, acceptance, and positive reinterpretation. Finally, worry positively impacts behavioral disengagement, self-control, seeking social support, mental disengagement, and planful problem-solving., Discussion: The study's originality lies in its investigation of consumers' coping strategies when experiencing negative emotions due to forced deconsumption in the context of the Covid-19 pandemic., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Ertz, Tandon, Yao Quenum, Salem and Sun.)

Given the continuous and excessive CO 2 emission into the atmosphere from anthropomorphic activities, there is now a growing demand for negative carbon emission technologies, which requires efficient capture and conversion of CO 2 to value-added chemicals. This review highlights recent advances in CO 2 capture and conversion chemistry and processes. It first summarizes various adsorbent materials that have been developed for CO 2 capture, including hydroxide-, amine-, and metal organic framework-based adsorbents. It then reviews recent efforts devoted to two types of CO 2 conversion reaction: thermochemical CO 2 hydrogenation and electrochemical CO 2 reduction. While thermal hydrogenation reactions are often accomplished in the presence of H 2 , electrochemical reactions are realized by direct use of electricity that can be renewably generated from solar and wind power. The key to the success of these reactions is to develop efficient catalysts and to rationally engineer the catalyst-electrolyte interfaces. The review further covers recent studies in integrating CO 2 capture and conversion processes so that energy efficiency for the overall CO 2 capture and conversion can be optimized. Lastly, the review briefs some new approaches and future directions of coupling direct air capture and CO 2 conversion technologies as solutions to negative carbon emission and energy sustainability.

We report the synthesis of Cu 2 O nanoparticles (NPs) by controlled oxidation of Cu NPs and the study of these NPs as a robust catalyst for ammonia borane dehydrogenation, nitroarene hydrogenation, and amine/aldehyde condensation into Schiff-base compounds. Upon investigation of the size-dependent catalysis for ammonia borane dehydrogenation and nitroarene hydrogenation using 8-18 nm Cu 2 O NPs, we found 13 nm Cu 2 O NPs to be especially active with quantitative conversion of nitro groups to amines. The 13 nm Cu 2 O NPs also efficiently catalyze tandem reactions of ammonia borane, diisopropoxy-dinitrobenzene, and terephthalaldehyde, leading to a controlled polymerization and the facile synthesis of polybenzoxazole (PBO). The highly pure PBO ( M w = 19 kDa) shows much enhanced chemical stability than the commercial PBO against hydrolysis in boiling water or simulated seawater, demonstrating a great potential of using noble metal-free catalysts for green chemistry synthesis of PBO as a robust lightweight structural material for thermally and mechanically demanding applications.

It has been a long-standing challenge to create and identify the active sites of heterogeneous catalysts, because it is difficult to precisely control the interfacial chemistry at the molecular level. Here we report the synthesis and catalysis of a heteroleptic gold trihydride nanocluster, [Au 22 H 3 (dppe) 3 (PPh 3 ) 8 ] 3+ [dppe = 1,2-bis(diphenylphosphino)ethane, PPh 3 = triphenylphosphine]. The Au 22 H 3 core consists of two Au 11 units bonded via six uncoordinated Au sites. The three H atoms bridge the six uncoordinated Au atoms and are found to play a key role in catalyzing electrochemical reduction of CO 2 to CO with a 92.7% Faradaic efficiency (FE) at -0.6 V (vs RHE) and high reaction activity (134 A/g Au mass activity). The CO current density and FE CO remained nearly constant for the CO 2 reduction reaction for more than 10 h, indicating remarkable stability of the Au 22 H 3 catalyst. The Au 22 H 3 catalytic performance is among the best Au-based catalysts reported thus far for electrochemical reduction of CO 2 . Density functional theory (DFT) calculations suggest that the hydride coordinated Au sites are the active centers, which facilitate the formation of the key *COOH intermediate.

This study aims to investigate the current state of sustainability for the collaborative economy (CE). By utilizing the triple bottom line as a founding conceptual framework, the study summarizes and discusses the sustainability of the CE from three dimensions: environment, economy, and society. The study further proposes some targeted measures and suggestions to measure the level of sustainability of the CE and CE platforms. The result shows that the CE has partially fulfilled some of its initial promises pertaining to sustainability, such as creating new job opportunities, economic growth, the efficient use of space and physical resources, as well as social mixing. However, the current sustainability benefits remain much smaller than some claim and hope for. Therefore, governments, platforms, and the public should work together to solve current challenges pertaining to the CE to tap its sustainability potential., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Sun and Ertz.)

We report a new form of catalyst based on ferromagnetic hexagonal-close-packed (hcp) Co nanosheets (NSs) for selective CO 2 RR to ethanal, CH 3 CHO. In all reduction potentials tested from -0.2 to -1.0 V (vs RHE) in 0.5 M KHCO 3 solution, the reduction yields ethanal as a major product and ethanol/methanol as minor products. At -0.4 V, the Faradaic efficiency (FE) for ethanal reaches 60% with current densities of 5.1 mA cm -2 and mass activity of 3.4 A g -1 (total FE for ethanal/ethanol/methanol is 82%). Density functional theory (DFT) calculations suggest that this high CO 2 RR selectivity to ethanal on the hcp Co surface is attributed to the unique intralayer electron transfer, which not only promotes [OC-CO]* coupling but also suppresses the complete hydrogenation of the coupling intermediates to ethylene, leading to highly selective formation of CH 3 CHO.

This study explores the key variables that influence overall waste minimization behaviors of consumers by augmenting the theory of planned behavior (TPB) with additional variables, including environmental concern, perceived consumer effectiveness, and perceived lack of facilities. Further, subjective norm is replaced by injunctive norm and descriptive norm. A questionnaire was administered to 455 consumers from North America, a region that faces acute waste production challenges. The findings suggest that perceived consumer effectiveness (PCE) constitutes the most influential variable to predict zero waste behavior (ZWB) intentions (β = 0.380 p < 0.001), even surpassing perceived behavioral control (PBC) (β = 0.232 p < 0.001), PBC also directly influences ZWB (β = 0.321 p < 0.001), and injunctive norms (β = 0.171 p < 0.05) exert a slightly greater influence than attitudes (β = 0.122 p < 0.001). Importantly, environmental concern is a meaningful antecedent to all belief variables (i.e., control belief [β = 0.689 p < 0.001], normative belief [β = 0.378 p < 0.001], and behavioral belief [β = 0.367p < 0.001]) while exerting an indirect effect on ZWB (β = 0.474 [0.299, 0.523]), especially via attitudes and PBC. Albeit perceived lack of facilities negatively impacts intentions (β = -0.073 p < 0.05), it positively relates ZWB (β = 0.189 p < 0.001) or worsens the effect of intentions on ZWB (β = -0.033 [-0.102, 0.036]). The results deliver crucial insights to devise impactful strategies and formulate sound policies to nudge consumers' ZWB., (Copyright © 2021. Published by Elsevier Ltd.)

Today's urban transportation systems face increasing challenges such as greenhouse gas (GHG) emissions, urban air quality, and traffic congestion. In this context, various initiatives of mutualized mobility have emerged. However, notably lacking is assessing the environmental impacts of mutualized transportation modes from a life cycle perspective. Using the actual urban transportation big data and related product life cycle data, this study combined with the life cycle assessment methodology and a "bottom-up" approach, explores the effect of mutualized mobility on greenhouse gas emissions of urban transportation systems for both Beijing and Toronto. The results showed that mutualized mobility might positively affect the sustainability of urban transport systems, albeit in very different ways. In Toronto, the annual per capita greenhouse gas emissions in 2016 decreased by 2.8 kg of carbon dioxide equivalent (CO 2 -eq) compared to 2011. Both carpooling and car-sharing displayed a higher curbing potential than ride-hailing. In a city characterized by higher population density like Beijing, ride-hailing created negative impacts. Deadheading (i.e., pulling an empty trailer) was the critical factor affecting ride-hailing's environmental performance, which accounted for about 30% of the total vehicle life cycle emissions. Counter-intuitively, greenhouse gas emissions of station-based bike-sharing (SBBS) were almost six times that of privately-owned bicycles and even higher than public transportation. This study's results can be used as a starting base for decision-makers to devise more appropriate strategies and programs to promote the sustainability of mutualized mobility and urban transportation systems. Meanwhile, it can also help the public at large to better understand the characteristics and environmental impacts of mutualized mobility to adopt more sustainable mutualized mobility alternatives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Developing an efficient single component photocatalyst for overall water splitting under visible-light irradiation is extremely challenging. Herein, we report a metal-free graphitic carbon nitride (g-CxN4)-based nanosheet photocatalyst (x = 3.2, 3.6, or 3.8) with melem rings conjugated by Schiff-base bonds (N[double bond, length as m-dash]C-C[double bond, length as m-dash]N). The presence of the conjugated Schiff-base bond tunes the band gap of g-CxN4 and, more importantly, serves as an electron sink to suppress electron-hole pair recombination. The projected density of states (PDOS) calculations suggest that the melem ring and Schiff-base bond act as oxidizing and reducing centers, respectively, for photocatalytic water splitting. As a result, g-CxN4, in particular g-C3.6N4, can catalyze overall water splitting without the need for any co-catalyst or sacrificial donor. Under visible light (>420 nm wavelength) irradiation, g-C3.6N4 catalyzes the overall water splitting with H2 and O2 generation rates of 75.0 and 36.3 μmol h-1 g-1, respectively. g-C3.6N4 is the most efficient single-component photocatalyst ever reported for overall water splitting. Our studies demonstrate a new approach for tuning the bandgap and the electronic structure of graphitic carbon nitride for maximizing its photocatalytic performance for water splitting, which will be important for hydrogen generation and for energy applications.

While nanoscale mimics of peroxidase have been extensively developed over the past decade or so, their catalytic efficiency as a key parameter has not been substantially improved in recent years. Herein, we report a class of highly efficient peroxidase mimic-nickel-platinum nanoparticles (Ni-Pt NPs) that consist of nickel-rich cores and platinum-rich shells. The Ni-Pt NPs exhibit a record high catalytic efficiency with a catalytic constant ( K cat ) as high as 4.5 × 10 7 s -1 , which is ∼46- and 10 4 -fold greater than the K cat values of conventional Pt nanoparticles and natural peroxidases, respectively. Density functional theory calculations reveal that the unique surface structure of Ni-Pt NPs weakens the adsorption of key intermediates during catalysis, which boosts the catalytic efficiency. The Ni-Pt NPs were applied to an immunoassay of a carcinoembryonic antigen that achieved an ultralow detection limit of 1.1 pg/mL, hundreds of times lower than that of the conventional enzyme-based assay.

Electrosynthesis is to use electricity to drive chemical reactions for chemical synthesis and is potentially a green approach to fuel and energy sustainability. Nanostructured catalysts play an important role in promoting electrochemical reactions under green chemistry conditions. This perspective first provides a brief tutorial on electrosynthesis and the roles the nanocatalysts play in the synthesis. It then outlines the common strategies used to develop nanocatalysts for hydrogen evolution reaction, CO 2 reduction reaction, and biomass upgrading. The perspective further summarizes the current methodologies that have been developed for scaling-up synthesis of nanocatalysts, which will be essential for the electrosynthesis to become a viable industry approach., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Enabling catalysts to promote multistep chemical reactions in a tandem fashion is an exciting new direction for the green chemistry synthesis of materials. Nanoparticle (NP) catalysts are particularly well suited for tandem reactions due to the diverse surface-active sites they offer. Here, we report that AuPd alloy NPs, especially 3.7 nm Au 42 Pd 58 NPs, catalyze one-pot reactions of formic acid, diisopropoxy-dinitrobenzene, and terephthalaldehyde, yielding a very pure thermoplastic rigid-rod polymer, polybenzoxazole (PBO), with a molecular weight that is tunable from 5.8 to 19.1 kDa. The PBO films are more resistant to hydrolysis and possess thermal and mechanical properties that are superior to those of commercial PBO, Zylon. Cu NPs are also active in catalyzing tandem reactions to form PBO when formic acid is replaced with ammonia borane. Our work demonstrates a general approach to the green chemistry synthesis of rigid-rod polymers as lightweight structural materials for broad thermomechanical applications.

The iron-based Fenton-type reaction has drawn tremendous attention in cancer therapy. Compared with oxidized iron, Fe(0) possesses high catalytic activity but unstable for biomedical application. Here, we report a new strategy to stabilize Fe(0) via a porous yolk shell nanostructure of Fe/Fe 3 O 4 (PYSNPs) in normal physiological condition, and to control the release of Fe(0) in tumor microenvironment for enhanced cancer therapy. These PYSNPs display superior tumor inhibition with the IC 50 down to 20 μg/mL (over 1 mg/mL for iron oxide nanoparticles as control) for HepG2 cell. A single intravenous injection of as low as 1 mg/kg dosage is effective to suppress tumor growth in vivo. Moreover, the disintegration of PYSNPs in the acidic tumor microenvironment could cause significant change in MRI signal for contrast-enhanced diagnosis. Of note, the resulting Fe 3 O 4 fragments are renal clearable with minimized side effect. In all, this work represented a nanoplatform to stabilize and selectively deliver Fe(0) for highly effective cancer therapy., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Tuning the performance of nanoparticle (NP) catalysts by controlling the NP surface strain has evolved as an important strategy to optimize NP catalysis in many energy conversion reactions. Here, we present our new study on using an eigenforce model to predict and experiments to verify the strain-induced catalysis enhancement of the oxygen reduction reaction (ORR) in the presence of L1 0 -CoMPt NPs (M = Mn, Fe, Ni, Cu, Ni). The eigenforce model allowed us to predict anisotropic (that is, two-dimensional) strain levels on distorted Pt(111) surfaces. Experimentally, by preparing a series of 5 nm L1 0 -CoMPt NPs, we could push the ORR catalytic activity of these NPs toward the optimum region of the theoretical two-dimensional volcano plot predicted for L1 0 -CoMPt. The best ORR catalyst in the alloy NP series we studied is L1 0 -CoNiPt, which has a mass activity of 3.1 A/mg Pt and a specific activity of 9.3 mA/cm 2 at room temperature with only 15.9% loss of mass activity after 30 000 cycles at 60 °C in 0.1 M HClO 4 .

An efficient CuPd nanoparticle (NP) catalyst (3 nm CuPd NPs deposited on carbon support) is designed for catalyzing electrochemical allylic alkylation in water/isopropanol (1:1 v/v) and 0.2 m KHCO 3 solution at room temperature. The Pd catalysis was Pd/Cu composition-dependent, and CuPd NPs with a Pd/Cu ratio close to one are the most efficient catalyst for the selective cross-coupling of alkyl halides and allylic halides to form C-C hydrocarbons with product yields reaching up to 99 %. This NP-catalyzed electrochemical allylic alkylation expands the synthetic scope of cross-coupling reactions and can be further extended to other organic reaction systems for developing green chemistry electrosynthesis methods., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

•As a novel and alternative type of fuel for heavy-duty trucks, it is very important to assess a broad array of environmental impacts of liquefied natural gas (LNG). However, few studies have evaluated comprehensively the environmental impact of LNG as an alternative fuel on human health, ecosystems and resources from a life cycle perspective. In particular, the environmental benefit of promoting LNG vehicles is often complicated and uncertain due to many variable factors, which are also often not given enough attention. This method article describes the use of a combination of life cycle assessment (LCA) and Monte Carlo simulation to evaluate the potential environmental benefits of promoting LNG heavy-duty diesel vehicles in Saguenay, a city in Canada. It not only conducts a full-range analysis of environmental impacts, but also considers the impact of joint changes in uncertain factors such as methane emission rates, energy efficiency of engine and the project promotion prospects on the environmental benefits of LNG, making life cycle environmental impact assessment more systematic and comprehensive. The paper provides the details of all the steps used in the method and can be replicated and applied to other similar studies and research settings.•This combined approach provides a comprehensive assessment of the environmental impacts incurred by the promotion of LNG vehicles. Besides, it also provides a certain degree of risk assessment for LNG projects.•This method takes into account the complexity of the joint change of multiple uncertainties, which makes up for the deficiencies of previous studies that only analyze one uncertainty in isolation.•This method takes the development prospect of LNG promoting project as an uncertain factor for environmental benefit assessment., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Author(s). Published by Elsevier B.V.)

Permanent magnets are a class of critical materials for information storage, energy storage, and other magneto-electronic applications. Compared with conventional bulk magnets, magnetic nanoparticles (MNPs) show unique size-dependent magnetic properties, which make it possible to control and optimize their magnetic performance for specific applications. The synthesis of MNPs has been intensively explored in recent years. Among different methods developed thus far, chemical synthesis based on solution-phase reactions has attracted much attention owing to its potential to achieve the desired size, morphology, structure, and magnetic controls. This Minireview focuses on the recent chemical syntheses of strongly ferromagnetic MNPs (H c >10 kOe) of rare-earth metals and FePt intermetallic alloys. It further discusses the potential of enhancing the magnetic performance of MNP composites by assembly of hard and soft MNPs into exchange-coupled nanocomposites. High-performance nanocomposites are key to fabricating super-strong permanent magnets for magnetic, electronic, and energy applications., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report a chemical method to synthesize size-controllable SmCo 5 nanoparticles (NPs) and to stabilize the NPs against air oxidation by coating a layer of N-doped graphitic carbon (NGC). First 10 nm CoO and 5 nm Sm 2 O 3 NPs were synthesized and aggregated in reverse micelles of oleylamine to form SmCo-oxide NPs with a controlled size (110, 150, or 200 nm). The SmCo-O NPs were then coated with polydopamine and thermally annealed to form SmCo-O/NGC NPs, which were further embedded in CaO matrix and reduced with Ca at 850 °C to give SmCo 5 /NGC NPs of 80, 120, or 180 nm, respectively. The 10 nm NGC coating efficiently stabilized the SmCo 5 NPs against air oxidation at room temperature or at 100 °C. The magnetization value of the 180 nm SmCo 5 /NGC NPs was stabilized at 86.1 emu/g 5 days after air exposure at room temperature and dropped only 1.7% 48 h after air exposure at 100 °C. The stable SmCo 5 /NGC NPs were aligned magnetically in an epoxy resin, showing a square-like hysteresis behavior with their H c reaching 51.1 kOe at 150 K and 21.9 kOe at 330 K and their M r stabilized at around 84.8 emu/g. Our study demonstrates a new strategy for synthesizing and stabilizing SmCo 5 NPs for high-performance nanomagnet applications in a broad temperature range.

While various effects of physicochemical parameters (e.g., size, facet, composition, and internal structure) on the catalytic efficiency of nanozymes (i.e., nanoscale enzyme mimics) have been studied, the strain effect has never been reported and understood before. Herein, we demonstrate the strain effect in nanozymes by using Pd octahedra and icosahedra with peroxidase-like activities as a model system. Strained Pd icosahedra were found to display 2-fold higher peroxidase-like catalytic efficiency than unstrained Pd octahedra. Theoretical analysis suggests that tensile strain is more beneficial to OH radical (a key intermediate for the catalysis) generation than compressive strain. Pd icosahedra are more active than Pd octahedra because icosahedra amplify the surface strain field. As a proof-of-concept demonstration, the strained Pd icosahedra were applied to an immunoassay of biomarkers, outperforming both unstrained Pd octahedra and natural peroxidases. The findings in this research may serve as a strong foundation to guide the design of high-performance nanozymes.

Understanding the Cu-catalyzed electrochemical CO 2 reduction reaction (CO 2 RR) under ambient conditions is both fundamentally interesting and technologically important for selective CO 2 RR to hydrocarbons. Current Cu catalysts studied for the CO 2 RR can show high activity but tend to yield a mixture of different hydrocarbons, posing a serious challenge on using any of these catalysts for selective CO 2 RR. Here, we report a new perovskite-type copper(I) nitride (Cu 3 N) nanocube (NC) catalyst for selective CO 2 RR. The 25 nm Cu 3 N NCs show high CO 2 RR selectivity and stability to ethylene (C 2 H 4 ) at -1.6 V (vs reversible hydrogen electrode (RHE)) with the Faradaic efficiency of 60%, mass activity of 34 A/g, and C 2 H 4 /CH 4 molar ratio of >2000. More detailed electrochemical characterization, X-ray photon spectroscopy, and density functional theory calculations suggest that the high CO 2 RR selectivity is likely a result of (100) Cu(I) stabilization by the Cu 3 N structure, which favors CO-CHO coupling on the (100) Cu 3 N surface, leading to selective formation of C 2 H 4 . Our study presents a good example of utilizing metal nitrides as highly efficient nanocatalysts for selective CO 2 RR to hydrocarbons that will be important for sustainable chemistry/energy applications.

The growth and breadth of nanoparticle (NP) research now encompasses many scientific and technologic fields, which has driven the want to control NP dimensions, structures and properties. Recent advances in NP synthesis, especially in solution phase synthesis, and characterization have made it possible to tune NP sizes and shapes to optimize NP properties for various applications. In this review, we summarize the general concepts of using solution phase chemistry to control NP nucleation and growth for the formation of monodisperse NPs with polyhedral, cubic, octahedral, rod, or wire shapes and complex multicomponent heterostructures. Using some representative examples, we demonstrate how to use these monodisperse NPs to tune and optimize NP catalysis of some important energy conversion reactions, such as the oxygen reduction reaction, electrochemical carbon dioxide reduction, and cascade dehydrogenation/hydrogenation for the formation of functional organic compounds under greener chemical reaction conditions. Monodisperse NPs with controlled surface chemistry, morphologies and magnetic properties also show great potential for use in biomedicine. We highlight how monodisperse iron oxide NPs are made biocompatible and target-specific for biomedical imaging, sensing and therapeutic applications. We intend to provide readers some concrete evidence that monodisperse NPs have been established to serve as successful model systems for understanding structure-property relationships at the nanoscale and further to show great potential for advanced nanotechnological applications.

We report a flame-reaction method to synthesize high-performance Sm x Co y (x=1, y=5; x=2, y=17) particles on a multigram scale. This flame reaction allows the controlled decomposition of Sm(NO 3 ) 3 and Co(NO 3 ) 2 to 320 nm SmCo-O (SmCoO 3 + Co 3 O 4 ) particles. A 5.8 g sample of SmCo 3.8 -O particles was coated with CaO and then reduced at 900 °C by Ca to give 4.2 g of 260 nm SmCo 5 particles. The SmCo 5 particles are strongly ferromagnetic and the aligned particles in epoxy resin exhibit a large room-temperature coercivity (H c ) of 41.8 kOe and giant (BH) max (maximum magnetic energy product) of 19.6 MGOe, the highest value ever reported for SmCo 5 made by chemical methods. This synthesis can be extended to synthesize Sm 2 Co 17 particles, providing a general approach to scaling up the synthesis of high-performance Sm x Co y nanomagnets for permanent magnet applications., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report a new strategy to prepare a composite catalyst for highly efficient electrochemical CO 2 reduction reaction (CO 2 RR). The composite catalyst is made by anchoring Au nanoparticles on Cu nanowires via 4,4'-bipyridine (bipy). The Au-bipy-Cu composite catalyzes the CO 2 RR in 0.1 m KHCO 3 with a total Faradaic efficiency (FE) reaching 90.6 % at -0.9 V to provide C-products, among which CH 3 CHO (25 % FE) dominates the liquid product (HCOO - , CH 3 CHO, and CH 3 COO - ) distribution (75 %). The enhanced CO 2 RR catalysis demonstrated by Au-bipy-Cu originates from its synergistic Au (CO 2 to CO) and Cu (CO to C-products) catalysis which is further promoted by bipy. The Au-bipy-Cu composite represents a new catalyst system for effective CO 2 RR conversion to C-products., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Efficient electro-oxidation of formic acid, methanol, and ethanol is challenging owing to the multiple chemical reaction steps required to accomplish full oxidation to CO 2 . Herein, a ternary CoPtAu nanoparticle catalyst system is reported in which Co and Pt form an intermetallic L1 0 -structure and Au segregates on the surface to alloy with Pt. The L1 0 -structure stabilizes Co and significantly enhances the catalysis of the PtAu surface towards electro-oxidation of ethanol, methanol, and formic acid, with mass activities of 1.55 A/mg Pt , 1.49 A/mg Pt , and 11.97 A/mg Pt , respectively in 0.1 m HClO 4 . The L1 0 -CoPtAu catalyst is also stable, with negligible degradation in mass activities and no obvious Co/Pt/Au composition changes after 10 000 potential cycles. The in situ surface-enhanced infrared absorption spectroscopy study indicates that the ternary catalyst activates the C-C bond more efficiently for ethanol oxidation., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Intermetallic nanoparticles (NPs) described in this Account are a class of metallic alloy NPs within which metal atoms are bonded via strong d- orbital interaction and ordered anisotropically in a specific crystallographic direction. Compared to the common metallic alloy NPs with solid solution structure, intermetallic NPs are generally more stable against chemical oxidation and etching. The strict stoichiometry requirement, well-defined atom binding environment and layered atomic arrangement also make intermetallic NPs an ideal model for understanding their physical and catalytic properties. This account summarizes the synthetic principles and strategies developed to obtain monodisperse intermetallic NPs, especially tetragonal L1 0 -NPs. The thermodynamics and kinetics involved in the conversion between disordered and ordered structures are briefly discussed. The synthetic methods are grouped into two slightly different categories: solution-phase synthesis followed by solid state annealing and direct solution-phase synthesis. In the former method, high-surface-area supports are often needed to disperse NPs and to prevent them from aggregation, while in the latter method such supports are not required since the structure conversion temperature is lowered to a level that the conversion can proceed in the solution reaction condition. In any of these two synthetic approaches, various factors influencing intermetallic structure formation should be carefully controlled to ensure more complete structural transition within NPs. Using representative synthetic examples, we highlight the strategies explored to facilitate the formation of intermetallic structure, including the introduction of vacancies/defects within NP structures and the control of atom addition rate/seed-mediated diffusion to lower the energy barrier. These strategies illustrate how the concept of thermodynamics and kinetics can be used to design the synthesis of intermetallic NPs. Additionally, to correlate NP structure and catalysis, we introduce briefly the d -band theory to explain how the electronic, strain and ensemble effects can be used to tune NP catalysis. We focus specifically on Pt-, Pd-, and Au-based L1 0 -NPs and demonstrate how these L1 0 -NPs could be prepared to show much enhanced catalysis for electrochemical reactions, including oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), formic acid oxidation reaction (FAOR), and thermo-oxidation reaction of CO. Due to the enhanced metal atom stability in the "sandwich"-type structure, the roles of the first-row transition metal atoms in catalysis are better understood to achieve catalysis optimization. This concept can be extended to other alloy NPs, demonstrating great potentials in using intermetallic structures to control NP reduction and oxidation catalysis for important chemical and energy applications.

We prepared micrometer long Cu nanowires (NWs) of 25 and 50 nm diameters and studied their electrocatalysis for electrochemical reduction of CO/CO 2 in 0.1 M KHCO 3 at room temperature. The 50 nm NWs showed better selectivity than the 25 nm NWs, and catalyzed CO reduction to C 2 -hydrocarbons (C 2 H 4 + C 2 H 6 ) with a combined faradaic efficiency (FE) of 60% (C 2 H 4 FE of 35% and mass activity of 4.25 A g -1 Cu) at -1.1 V (vs. reversible hydrogen electrode). The NW-catalyzed CO 2 reduction is less efficient due to the extra CO 2 to CO step required for the formation of C 2 -hydrocarbons. This experimental evidence combined with DFT calculations suggests that CO is an important intermediate and NWs provide a large Cu(100) surface for *CO hydrogenation (to *CHO) and *CO-*CHO coupling, leading to more selective reduction of CO than CO 2 towards C 2 -hydrocarbons.

We report a general chemical approach to synthesize strongly ferromagnetic rare-earth metal (REM) based SmCo and SmFeN nanoparticles (NPs) with ultra-large coercivity. The synthesis started with the preparation of hexagonal CoO+Sm 2 O 3 (denoted as SmCo-O) multipods via decomposition of Sm(acac) 3 and Co(acac) 3 in oleylamine. These multipods were further reduced with Ca at 850 °C to form SmCo 5 NPs with sizes tunable from 50 to 200 nm. The 200 nm SmCo 5 NPs were dispersed in ethanol, and magnetically aligned in polyethylene glycol (PEG) matrix, yielding a PEG-SmCo 5 NP composite with the room temperature coercivity (H c ) of 49.2 kOe, the largest H c among all ferromagnetic NPs ever reported, and saturated magnetic moment (M s ) of 88.7 emu g -1 , the highest value reported for SmCo 5 NPs. The method was extended to synthesize other ferromagnetic NPs of Sm 2 Co 17 , and, for the first time, of Sm 2 Fe 17 N 3 NPs with H c over 15 kOe and M s reaching 127.9 emu g -1 . These REM based NPs are important magnetic building blocks for fabrication of high-performance permanent magnets, flexible magnets, and printable magnetic inks for energy and sensing applications., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Self-assembly of nanoparticles (NPs) is at the heart of nanotechnology, and has shown many potential applications in fabricating nanodevices with highly controlled functionality. Two-dimensional (2D) arrays of NPs can provide a thin and uniform NP array with each NP being exposed on the surface to maximize NP catalysis. This minireview summarizes the recent progress on the fabrication and application of 2D NP arrays. It conveys the important message to readers that creation of libraries of NP arrays with varying catalytic strengths is an exciting direction in catalysis. This approach can be used to solve complicated catalytic problems in which multiple chemical reactions need to be catalyzed in a single reaction vessel., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report a new strategy of controlling catalytic activity and selectivity of Cu nanoparticles (NPs) for the ammonia borane initiated hydrogenation reaction. Cu NPs are active and selective for chemoselective reduction of nitrostyrene to vinylaniline under ambient conditions. Their activity, selectivity, and more importantly, stability are greatly enhanced by their anchoring on WO 2.72 nanorods, providing a room-temperature full conversion of nitrostyrene selectively to vinylaniline (>99% yield). Compared with all other catalysts developed thus far, our new Cu/WO 2.72 catalyst shows much enhanced hydrogenation selectivity and stability without the use of pressured hydrogen. The synthetic approach demonstrated here can be extended to prepare various M/WO 2.72 catalysts (M = Fe, Co, Ni), with M being stabilized for many chemical reactions.

We report a strategy to enhance the room temperature low-field magnetoresistance (LFMR) behavior of Fe3O4 nanoparticle (NP) assemblies by controlled Zn-substitution. The Zn-substituted 7 nm ZnxFe3-xO4, (x = 0 to 0.4) NPs are prepared by thermal decomposition of metal acetylacetonates (M(acac)n, M = Fe2+, Fe3+, and Zn2+). The substitution increases NP magnetic susceptibility (χ) and makes the magnetic moment more sensitive to low magnetic fields. As a result, the Zn0.3Fe2.7O4 NP assembly with NPs separated by tridecanoate exhibits a large magnetoresistance (MR) ratio of -14.8% at 300 K under a 4.5 kOe magnetic field. The demonstrated approach to control NP substitution to enhance low-field magnetoresistance of the NP assemblies provides an attractive new strategy to fabricate Fe3O4-based magnetic NP assemblies with desirable transport properties for sensitive spintronic applications.

Ni 30 Pd 70 nanoparticles supported on nitrogen-doped graphene (NG) acts as a catalyst for the hydrodehalogenation of halogenated aromatics under mild reaction conditions. It reduces mono- or dichloroarenes to the corresponding dehalogenated arenes in >90 % yield in 10 % aqueous isopropanol solvent at or below 50 °C within 5 h. Tests on a variety of substrates containing various functional groups show that the catalyst is selective for reduction of C-Cl and C-Br bonds. In addition, this catalyst completely hydrodehalogenates high-concentration solutions of dioxin, polychlorinated biphenyls, chloroaromatic constituents of the defoliant agent orange, and polybrominated diphenyl ethers in 12 h. The catalyst is reusable and shows no morphological or compositional changes after 5 cycles. This methodology offers a powerful, low-cost, and safe technology for the degradation of polyhalogenated aromatics, and may be useful for preventing proliferation of these toxins in the environment from causing serious health issues., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report a simple strategy to synthesize anisotropic SmCo5 nanoplates. The strategy involves the pre-synthesis of 125 × 12 nm Sm(OH)3 nanorods and 10 nm Co nanoparticles followed by the self-assembly of these nanorods and nanoparticles into Sm(OH)3-Co nanocomposites. Once embedded in a CaO matrix, the nanocomposite is subjected to high temperature (850 °C) annealing in the presence of Ca, leading to the formation of 125 × 10 nm SmCo5 nanoplates, which are dispersible in ethanol, allowing the alignment in epoxy resin under a 20 kOe magnetic field. The aligned SmCo5 nanoplates show a square hysteresis behavior with room temperature coercivity reaching 30.1 kOe, which is among the highest values ever reported for SmCo5 made from chemical methods. This work provides a new approach to high-performance anisotropic SmCo5 for permanent magnetic applications.

We report in this article a detailed study on how to stabilize a first-row transition metal (M) in an intermetallic L1 0 -MPt alloy nanoparticle (NP) structure and how to surround the L1 0 -MPt with an atomic layer of Pt to enhance the electrocatalysis of Pt for oxygen reduction reaction (ORR) in fuel cell operation conditions. Using 8 nm FePt NPs as an example, we demonstrate that Fe can be stabilized more efficiently in a core/shell structured L1 0 -FePt/Pt with a 5 Å Pt shell. The presence of Fe in the alloy core induces the desired compression of the thin Pt shell, especially the two atomic layers of Pt shell, further improving the ORR catalysis. This leads to much enhanced Pt catalysis for ORR in 0.1 M HClO 4 solution (at both room temperature and 60 °C) and in the membrane electrode assembly (MEA) at 80 °C. The L1 0 -FePt/Pt catalyst has a mass activity of 0.7 A/mg Pt from the half-cell ORR test and shows no obvious mass activity loss after 30 000 potential cycles between 0.6 and 0.95 V at 80 °C in the MEA, meeting the DOE 2020 target (<40% loss in mass activity). We are extending the concept and preparing other L1 0 -MPt/Pt NPs, such as L1 0 -CoPt/Pt NPs, with reduced NP size as a highly efficient ORR catalyst for automotive fuel cell applications.

We report a facile method for assembly of a monolayer array of nitrogen-doped graphene (NG) and nanoparticles (NPs) and the subsequent transfer of two layers onto a solid substrate (S). Using 3 nm NiPd NPs as an example, we demonstrate that NiPd-NG-Si (Si=silicon wafer) can function as a catalyst and show maximum NiPd catalysis for the hydrolysis of ammonia borane (H 3 NBH 3 , AB) with a turnover frequency (TOF) of 4896.8 h -1 and an activation energy (E a ) of 18.8 kJ mol -1 . The NiPd-NG-S catalyst is also highly active for catalyzing the transfer hydrogenation from AB to nitro compounds, leading to the green synthesis of quinazolines in water. Our assembly method can be extended to other graphene and NP catalyst materials, providing a new 2D NP catalyst platform for catalyzing multiple reactions in one pot with maximum efficiency., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Stabilizing a 3d-transition metal component M from an MPd alloy structure in an acidic environment is key to the enhancement of MPd catalysis for various reactions. Here we demonstrate a strategy to stabilize Cu in 5 nm CuPd nanoparticles (NPs) by coupling the CuPd NPs with perovskite-type WO 2.72 nanorods (NRs). The CuPd NPs are prepared by controlled diffusion of Cu into Pd NPs, and the coupled CuPd/WO 2.72 are synthesized by growing WO 2.72 NRs in the presence of CuPd NPs. The CuPd/WO 2.72 can stabilize Cu in 0.1 M HClO 4 solution and, as a result, they show Cu, Pd composition dependent activity for the electrochemical oxidation of formic acid in 0.1 M HClO 4 + 0.1 M HCOOH. Among three different CuPd/WO 2.72 studied, the Cu 48 Pd 52 /WO 2.72 is the most efficient catalyst, with its mass activity reaching 2086 mA/mg Pd in a broad potential range of 0.40 to 0.80 V (vs RHE) and staying at this value after the 12 h chronoamperometry test at 0.40 V. The synthesis can be extended to obtain other MPd/WO 2.72 (M = Fe, Co, Ni), making it possible to study MPd-WO 2.72 interactions and MPd stabilization on enhancing MPd catalysis for various chemical reactions.

We report a new strategy for stabilizing Fe nanoparticles (NPs) in the preparation of SmCo 5 -Fe nanocomposites. We coat the presynthesized Fe NPs with SiO 2 and assemble the Fe/SiO 2 NPs with Sm-Co-OH to form a mixture. After reductive annealing at 850 °C in the presence of Ca, we obtain SmCo 5 -Fe/SiO 2 composites. Following aqueous NaOH washing and compaction, we produced exchange-coupled SmCo 5 -Fe nanocomposites with Fe NPs controlled at 12 nm. Our work demonstrates a successful strategy of stabilizing high moment magnetic NPs in a hard magnetic matrix to produce a nanocomposite with tunable magnetic properties.