The high solubility of polysulfides in the electrolyte, together with the resulting poor cycling performance, is one of the main obstacles to the industrial production and use of lithium-sulfur ...(Li-S) batteries. We have developed a novel hybrid and dense separator coating that greatly improves the cycling and rate performance of the battery. The coating is fabricated by mono-dispersed Li4Ti5O12 (LTO) nanospheres uniformly embedded in graphene layers. In this hybrid dense coating, the LTO nanospheres have a high chemical affinity for polysulfides and an excellent ionic conductivity to produce highly efficient ionic conductive channels, while the graphene layers play twin roles as a physical barrier for polysulfides and an upper current collector. The unique hybridization guarantees a very dense coating that does not significantly add the volume of the battery and meanwhile achieves an ideal combination of an effective barrier for polysulfide diffusion with a fast ion transport. For a normal coating, a loose and very thick structure is needed to meet these requirements. Cells using a pure sulfur electrode with the dense coating separator show an ultra-high rate performance (709mAhg−1 at 2C and 1408mAhg−1 at 0.1C) and an excellent cycling performance (697mAhg−1 after 500 cycles at 1C with 85.7% capacity retention). The easy achieving of such excellent performance indicates the possibility of producing an industrially practical Li-S battery.
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•A dense and hybrid coating is fabricated on separator for long life Li-S Battery.•The coating contains Li4Ti5O12 nanospheres embedded in graphene layers.•The coating combines physical barrier with chemical adsorption for polysulfides.•A fast lithium ion transport is achieved by Li4Ti5O12 nanospheres.
The direct electrochemical nitric oxide reduction reaction (NORR) is an attractive technique for converting NO into NH3 with low power consumption under ambient conditions. Optimizing the electronic ...structure of the active sites can greatly improve the performance of electrocatalysts. Herein, we prepare body‐centered cubic RuGa intermetallic compounds (i.e., bcc RuGa IMCs) via a substrate‐anchored thermal annealing method. The electrocatalyst exhibits a remarkable NH4+ yield rate of 320.6 μmol h−1 mg−1Ru with the corresponding Faradaic efficiency of 72.3 % at very low potential of −0.2 V vs. reversible hydrogen electrode (RHE) in neutral media. Theoretical calculations reveal that the electron‐rich Ru atoms in bcc RuGa IMCs facilitate the adsorption and activation of *HNO intermediate. Hence, the energy barrier of the potential‐determining step in NORR could be greatly reduced.
The body‐centered cubic RuGa intermetallic compounds (i.e., bcc RuGa IMCs) are prepared via a substrate‐anchored thermal annealing method. Electron‐rich Ru atoms are the active sites and are isolated in bcc RuGa IMCs, which promote electron transfer from the electrocatalyst to key intermediates, thereby effectively improving the electrocatalytic performance of the nitric oxide reduction reaction (NORR).
Ordered intermetallic nanomaterials with a well‐defined crystal structure and fixed stoichiometry facilitate the predictable control of their electronic structure and catalytic performance. To obtain ...the thermodynamically stable intermetallic structures, the conventional approaches with high‐temperature annealing are still far from satisfactory, because of annealing‐induced aggregation and sintering of nanomaterials. Herein, a general wet‐chemical method is developed to synthesize a series of noble metal–based intermetallic nanocrystals, including hexagonal close‐packed (hcp) PtBi nanoplates, face‐centered cubic (fcc) Pd3Pb nanocubes, and hcp Pd2.5Bi1.5 nanoparticles. During the synthetic process, Br− ions play two important roles for the formation of ordered intermetallic structures: i) Br− ions can coordinate with the metal ions to decrease their reduction potentials thus slowing down the reduction kinetics. ii) Br− ions can combine with molecular oxygen to generate an oxidative etching effect, hence reconstructing the atom arrangement, which is beneficial for the formation of the intermetallic structure. As a proof‐of‐concept application, Pd3Pb nanocubes are used as electrocatalysts for ethanol and methanol oxidation reactions, which exhibit significantly improved electrochemical performance compared with the commercial Pd black catalyst.
A general wet‐chemical method is developed to synthesize a series of noble Metal–Based intermetallic nanocrystals, in which Br− ions play important roles in the formation of atomically ordered structures. The obtained Pd3Pb nanocubes exhibit superior electrocatalytic performance for ethanol and methanol oxidation reactions.
The electrochemical CO2 reduction reaction (CO2RR) offers a green and sustainable process to convert CO2 into valuable chemical stocks and fuels. Metal is one of the most promising types of catalysts ...to drive an efficient and selective CO2RR. The catalytic performance of metal nanocatalysts is strongly dependent on their structural features. Recently, phase engineering of nanomaterials (PEN) has emerged as a prominent tactic to regulate the catalytic performance of metal nanocatalysts for the CO2RR. A broad range of metal nanocatalysts with conventional and unconventional crystal phases has been developed, and remarkable achievements have been made. This review summarizes the most recent developments in phase engineering of metal nanocatalysts for the electrochemical CO2RR. We first introduce the different crystal phases of metal nanocatalysts used in the CO2RR and then discuss various synthetic strategies for unconventional phases of metal nanocatalysts. After that, detailed discussions of metal nanocatalysts with conventional and unconventional phases, including amorphous phases, are presented. Finally, the challenges and perspectives in this emerging area are discussed.
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•Phase engineering of nanomaterials (PEN) emerges as a promising tactic to regulate their electrocatalytic performances.•Recent development in phase engineering of metal nanocatalysts for electrochemical CO2 reduction reaction was summarized.•Challenges and perspectives towards phase engineering of metal nanocatalysts for electrochemical CO2 reduction were proposed.
Constructing amorphous/intermetallic (A/IMC) heterophase structures by breaking the highly ordered IMC phase with disordered amorphous phase is an effective way to improve the electrocatalytic ...performance of noble metal‐based IMC electrocatalysts because of the optimized electronic structure and abundant heterophase boundaries as active sites. In this study, we report the synthesis of ultrathin A/IMC PtPbBi nanosheets (NSs) for boosting hydrogen evolution reaction (HER) and alcohol oxidation reactions. The resulting A/IMC PtPbBi NSs exhibit a remarkably low overpotential of only 25 mV at 10 mA cm−2 for the HER in an acidic electrolyte, together with outstanding stability for 100 h. In addition, the PtPbBi NSs show high mass activities for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), which are 13.2 and 14.5 times higher than those of commercial Pt/C, respectively. Density functional theory calculations demonstrate that the synergistic effect of amorphous/intermetallic components and multimetallic composition facilitate the electron transfer from the catalyst to key intermediates, thus improving the catalytic activity of MOR. This work establishes a novel pathway for the synthesis of heterophase two‐dimensional nanomaterials with high electrocatalytic performance across a wide range of electrochemical applications.
Ultrathin amorphous/intermetallic heterophase PtPbBi NSs were synthesized for the first time, which exhibited excellent electrocatalytic performance in HER and AORs owing to their unique heterointerfaces and abundant exposed active sites. Construction of amorphous/crystalline heterophase structures with multimetallic composition can effectively optimize the Gibbs free energy and enhance the electron transfer from the surface of the catalyst to *CH2OH.
Intermetallic nanomaterials have shown promising potential as high‐performance catalysts in various catalytic reactions due to their unconventional crystal phases with ordered atomic arrangements. ...However, controlled synthesis of intermetallic nanomaterials with tunable crystal phases and unique hollow morphologies remains a challenge. Here, a seeded method is developed to synthesize hollow PdSn intermetallic nanoparticles (NPs) with two different intermetallic phases, that is, orthorhombic Pd2Sn and monoclinic Pd3Sn2. Benefiting from the rational regulation of the crystal phase and morphology, the obtained hollow orthorhombic Pd2Sn NPs deliver excellent electrocatalytic performance toward glycerol oxidation reaction (GOR), outperforming solid orthorhombic Pd2Sn NPs, hollow monoclinic Pd3Sn2 NPs, and commercial Pd/C, which places it among the best reported Pd‐based GOR electrocatalysts. The reaction mechanism of GOR using the hollow orthorhombic Pd2Sn as the catalyst is investigated by operando infrared reflection absorption spectroscopy, which reveals that the hollow orthorhombic Pd2Sn catalyst cleaves the CC bond more easily compared to the commercial Pd/C. This work can pave an appealing route to the controlled synthesis of diverse novel intermetallic nanomaterials with hollow morphology for various promising applications.
A seeded method is developed to prepare hollow PdSn intermetallic nanoparticles, i.e., orthorhombic Pd2Sn and monoclinic Pd3Sn2, based on rational modulation of phase and morphology. The obtained hollow orthorhombic Pd2Sn nanoparticles with modified electronic structure, high intrinsic activity, and abundant active sites exhibit excellent catalytic performances toward electrochemical glycerol oxidation, outperforming hollow monoclinic Pd3Sn2 and solid orthorhombic Pd2Sn nanoparticles.
This work demonstrates how a very low fraction of graphene greatly enhances the usage efficiency of carbon-based conductive additive in LiCoO2-based lithium ion batteries (LIB) and develops a ...strategy using binary conductive additive to have a high performance battery, especially with excellent rate performance. With a much lower fraction of carbon additive for a commercial LIB, only 0.2 wt% graphene nanosheet (GN) together with 1 wt% Super-P (SP) constructing an effective conductive network, the prepared battery exhibits outstanding cycling stability (146 mAhg−1 at 1C with retention of 96.4% after 50 cycles) and rate capability (116.5 mAhg−1 even at 5C). In this battery, a composite conducting network is formed with a long-range electron pathway formed by a trace amount of GN and the short-range electron pathway by aggregation of SP particles. More interestingly, in micro-sized LiCoO2 system, the GN additive does not present hindrance effect for lithium ion transport even in high rate discharge, which is entirely different from the nano-sized LiFePO4 system. This study further demonstrates commercial potential of GN additive for high performance LIB and more importantly gives a well-designed recipe for its real application.
Structural engineering of nanomaterials offers a promising way for developing high‐performance catalysts toward catalysis. However, the delicate modulation of thermodynamically unfavorable ...nanostructures with unconventional phases still remains a challenge. Here, the synthesis of hierarchical AuCu nanostructures is reported with hexagonal close‐packed (2H‐type)/face‐centered cubic (fcc) heterophase, high‐index facets, planar defects (e.g., stacking faults, twin boundaries, and grain boundaries), and tunable Cu content. The obtained 2H/fcc Au99Cu1 hierarchical nanosheets exhibit excellent performance for the electrocatalytic CO2 reduction to produce CO, outperforming the 2H/fcc Au91Cu9 and fcc Au99Cu1. The experimental results, especially those obtained by in‐situ differential electrochemical mass spectroscopy and attenuated total reflection Fourier‐transform infrared spectroscopy, suggest that the enhanced catalytic performance of 2H/fcc Au99Cu1 arises from the unconventional 2H/fcc heterophase, high‐index facets, planar defects, and appropriate alloying of Cu. Impressively, the 2H/fcc Au99Cu1 shows CO Faradaic efficiencies of 96.6% and 92.6% at industrial current densities of 300 and 500 mA cm−2, respectively, as well as good durability, placing it among the best CO2 reduction electrocatalysts for CO production. The atomically structural regulation based on phase engineering of nanomaterials (PEN) provides an avenue for the rational design and preparation of high‐performance electrocatalysts for various catalytic applications.
2H/fcc‐heterophase AuCu hierarchical nanostructures, i.e., Au99Cu1 and Au91Cu9, are synthesized via a facile one‐pot wet‐chemical method. The obtained 2H/fcc Au99Cu1 hierarchical nanosheets show superior performance of electrochemical CO2 reduction toward the CO production at industrial current densities due to the unique structural features, including unconventional 2H/fcc heterophase, high‐index facets, planar defects, and appropriate alloying of Cu.
Noble metals have been widely used in catalysis, however, the scarcity and high cost of noble metal motivate researchers to balance the atomic efficiency and atomic density, which is formidably ...challenging. This article proposes a robust strategy for fabricating 3D amorphous noble metal‐based oxides with simultaneous enhancement on atomic efficiency and density with the assistance of atomic channels, where the atomic utilization increases from 18.2% to 59.4%. The unique properties of amorphous bimetallic oxides and formation of atomic channels have been evidenced by detailed experimental characterizations and theoretical simulations. Moreover, the universality of the current strategy is validated by other binary oxides. When Cu2IrOx with atomic channels (Cu2IrOx‐AE) is used as catalyst for oxygen evolution reaction (OER), the mass activity and turnover frequency value of Cu2IrOx‐AE are 1–2 orders of magnitude higher than CuO/IrO2 and Cu2IrOx without atomic channels, largely outperforming the reported OER catalysts. Theoretical calculations reveal that the formation of atomic channels leads to various Ir sites, on which the proton of adsorbed *OH can transfer to adjacent O atoms of IrO6. This work may attract immediate interest of researchers in material science, chemistry, catalysis, and beyond.
3D amorphous noble metal‐based oxides with simultaneous enhancement on atomic efficiency and density are synthesized by the assistance of atomic channels, where the atomic utilization increases from 18.2% to 59.4%. The mass activity and turnover frequency value of OER for Cu2IrOx‐AE are 1–2 orders of magnitude higher than CuO/IrO2‐C and Cu2IrOx‐A.
ABSTRACT
Phase engineering is arising as an attractive strategy to tune the properties and functionalities of nanomaterials. In particular, amorphous/crystalline heterophase nanostructures have ...exhibited some intriguing properties. Herein, the one-pot wet-chemical synthesis of two types of amorphous/crystalline heterophase PdCu nanosheets is reported, in which one is amorphous phase-dominant and the other one is crystalline phase-dominant. Then the aging process of the synthesized PdCu nanosheets is studied, during which their crystallinity increases, accompanied by changes in some physicochemical properties. As a proof-of-concept application, their aging effect on catalytic hydrogenation of 4-nitrostyrene is investigated. As a result, the amorphous phase-dominant nanosheets initially show excellent chemoselectivity. After aging for 14 days, their catalytic activity is higher than that of crystalline phase-dominant nanosheets. This work demonstrates the intriguing properties of heterophase nanostructures, providing a new platform for future studies on the regulation of functionalities and applications of nanomaterials by phase engineering.
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