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.
As a unique two-dimensional (2D) material, 2D noble metal-based intermetallic compounds (IMCs) have attracted much attention in electrocatalysis owing to their exceptional physical and chemical ...properties. However, the synthesis of 2D noble metal-based IMCs with well-defined structures remains challenging. This comprehensive review begins by delving into the morphology modulation of 2D noble metal-based IMCs, highlighting their key synthesis strategies, such as the CO-assisted and halide ion modulation methods. Subsequently, we discuss the advantages of 2D noble metal-based IMCs in electrocatalysis, including oxygen reduction reaction, alcohol oxidation reaction, formic acid oxidation reaction, and hydrogen evolution reaction. Finally, the main challenges and perspectives for the future development of 2D noble metal-based IMC electrocatalysts are presented to accelerate their promising commercialization.
Developing high-performance electrocatalysts for CO2 reduction reaction (CO2RR) is crucial since it is beneficial for environmental protection and the resulting value-add chemical products can act as ...an alternative to fossil feedstocks. Nonetheless, the direct reduction of CO2 into long-chain hydrocarbons and oxygenated hydrocarbons with high selectivity remains challenging. Copper (Cu) shows a distinctive advantage that it is the only pure metal catalyst for reducing CO2 into multi-carbon (C2+) products and the certain facets (e.g., (100), (111), (111)) of Cu nanocrystals exhibit relatively low energy barriers for the formation of specific products (e.g., CO, HCOOH, CH4, C2H4, C2H5OH, and other C2+ products). Therefore, extensive studies have been carried out to explore the relationship between the facets of Cu nanocrystals and corresponding catalytic products. In this review, we will discuss the crystal facet-dependent electrocatalytic CO2RR performance in metallic Cu catalysts, meanwhile, the detailed reaction mechanisms will be systematically summarized. In addition, we will provide a personal perspective for the future research directions in this emerging field. We believe this review is helpful to guide the design of high-selectivity Cu-based electrocatalysts for CO2RR.
In this review, we discuss the crystal facet-dependent electrocatalytic CO2 reduction performance in metallic Cu catalysts, meanwhile, the detailed reaction mechanisms are systematically summarized. Display omitted
Twinning commonly exists in noble metals. In recent years, it has attracted increasing interest as it is powerful to tune the physicochemical properties of metallic nanomaterials. To the best of our ...knowledge, all the reported twinned noble metal structures exclusively possess the close-packed {111} twinning plane. Here, we report the discovery of non-close-packed twinning planes in our synthesized Au nanokites. By using the bent Au nanoribbons with unique 4H/face-centered cubic)/4H crystal-phase heterostructures as templates, Au nanokites with unusual twinned 4H-phase structures have been synthesized, which possess the non-close-packed {10Formula: see text2} or {10Formula: see text6} twinning plane. By using the Au nanokites as templates, twinned 4H-phase Au@Ag and Au@PdAg core-shell nanostructures have been synthesized. The discovery of 4H-phase twinned noble metal nanostructures may pave a way for the preparation of metal nanomaterials with unique twinned structures for various promising applications.
Metallic nanostructures are commonly densely packed into a few packing variants with slightly different atomic packing factors. The structural aspects and physicochemical properties related with the ...vacancies in such nanostructures are rarely explored because of lack of an effective way to control the introduction of vacancy sites. Highly voided metallic nanostructures with ordered vacancies are however energetically high lying and very difficult to synthesize. Here, we report a chemical method for synthesis of hierarchical Rh nanostructures (Rh NSs) composed of ultrathin nanosheets, composed of hexagonal close-packed structure embedded with nanodomains that adopt a vacated Barlow packing with ordered vacancies. The obtained Rh NSs exhibit remarkably enhanced electrocatalytic activity and stability toward the hydrogen evolution reaction (HER) in alkaline media. Theoretical calculations reveal that the exceptional electrocatalytic performance of Rh NSs originates from their unique vacancy structures, which facilitate the adsorption and dissociation of H
O in the HER.
As an effective method to modulate the physicochemical properties of materials, crystal phase engineering, especially hetero‐phase, plays an important role in developing high‐performance ...photocatalysts. However, it is still a huge challenge but significant to construct porous hetero‐phase nanostructures with adjustable band structures. As a kind of unique porous crystalline materials, metal–organic frameworks (MOFs) might be the appropriate candidate, but the MOF‐based hetero‐phase is rarely reported. Herein, we developed a secondary building unit (SBU) regulating strategy to prepare two crystal phases of Ti‐MOFs constructed by titanium and 1,4‐dicarboxybenzene, i.e., COK and MIL‐125. Besides, COK/MIL‐125 hetero‐phase was further constructed. In the photocatalytic hydrogen evolution reaction, COK/MIL‐125 possessed the highest H2 yield compared to COK and MIL‐125, ascribing to the Z‐Scheme homojunction at hetero‐phase interface. Furthermore, by decorating with amino groups (i.e., NH2‐COK/NH2‐MIL‐125), the light absorbing capacity was broadened to visible‐light region, and the visible‐light‐driven H2 yield was greatly improved. Briefly, the MOF‐based hetero‐phase possesses periodic channel structures and molecularly adjustable band structures, which is scarce in traditional organic or inorganic materials. As a proof of concept, our work not only highlights the development of MOF‐based hetero‐phase nanostructures, but also paves a novel avenue for designing high‐performance photocatalysts.
Via an SBU regulating strategy, MOF‐based hetero‐phase (COK/MIL‐125) was successfully prepared and employed in photocatalysis. This novel hetero‐phase not only possesses periodic channel structures, but also exhibits the capacity of molecular‐scale adjustment on energy levels.
Carbon materials have great potential for being the anode of choice in alkali metal ion batteries and are also crucial for constructing an efficient spatial framework for the production of alloy ...anodes with higher capacities. For the design of practical carbon anodes, the criteria of sufficient charge storage, a high initial coulombic efficiency, and excellent stability are proposed, which calls for the selection and optimization of the carbon microstructure as well as the matching of electrolytes. For the design of the carbon framework for alloy anodes, the principles of interfacial cohesion, spatial interconnection, and structural stability are proposed, thus recommending a proactive design strategy for better stability and volumetric performance. Research history together with representative research progress is reviewed and discussed in detail in an attempt to stimulate more research interest and promote ideas for the critical search for the right carbon to use as an anode in alkali metal ion batteries. Lastly, specific bottlenecks restricting the successful transfer of these carbons from laboratory to industry are highlighted. The importance of a precise understanding of the charge storage mechanism, the development of matching electrolytes, and the ability to produce the necessary carbon framework in large quantity for higher capacity alloy anodes are discussed.
Carbon materials are potential for being the practical anodes in alkali metal ion batteries (AMIBs) and also crucial for constructing an efficient spatial framework for alloy anodes with higher capacities. Research history together with representative research progress is reviewed and discussed in an attempt to promote ideas regarding the critical search for the right carbon for practical anodes in AMIBs.
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.
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).
PDF
