Self-assembly of colloidal nanoparticles (NPs) into superstructures offers a flexible and promising pathway to manipulate the nanometer-sized particles and thus make full use of their unique ...properties. This bottom-up strategy builds a bridge between the NP regime and a new class of transformative materials across multiple length scales for technological applications. In this field, anisotropic NPs with size- and shape-dependent physical properties as self-assembly building blocks have long fascinated scientists. Self-assembly of anisotropic NPs not only opens up exciting opportunities to engineer a variety of intriguing and complex superlattice architectures, but also provides access to discover emergent collective properties that stem from their ordered arrangement. Thus, this has stimulated enormous research interests in both fundamental science and technological applications. This present review comprehensively summarizes the latest advances in this area, and highlights their rich packing behaviors from the viewpoint of NP shape. We provide the basics of the experimental techniques to produce NP superstructures and structural characterization tools, and detail the delicate assembled structures. Then the current understanding of the assembly dynamics is discussed with the assistance of
in situ
studies, followed by emergent collective properties from these NP assemblies. Finally, we end this article with the remaining challenges and outlook, hoping to encourage further research in this field.
This review provides an overview of the recent achievements in self-assembly of colloidal nanoparticles with anisotropic shapes into functional superstructures.
Novel inorganic lead‐free double perovskites with improved stability are regarded as alternatives to state‐of‐art hybrid lead halide perovskites in photovoltaic devices. The recently discovered ...Cs2AgBiBr6 double perovskite exhibits attractive optical and electronic features, making it promising for various optoelectronic applications. However, its practical performance is hampered by the large band gap. In this work, remarkable band gap narrowing of Cs2AgBiBr6 is, for the first time, achieved on inorganic photovoltaic double perovskites through high pressure treatments. Moreover, the narrowed band gap is partially retainable after releasing pressure, promoting its optoelectronic applications. This work not only provides novel insights into the structure–property relationship in lead‐free double perovskites, but also offers new strategies for further development of advanced perovskite devices.
High pressure is adopted to modulate the crystal structure and engineer the band gap of the Cs2AgBiBr6 double perovskite. A 22.3 % band gap narrowing is achieved for the inorganic photovoltaic double perovskite. The narrowed band gap is partially retainable after releasing the pressure, promoting its optoelectronic applications.
The formation of novel and complex structures with specific morphologies from nanocrystals via a direct assembly of atoms or ions remains challenging. In recent years, researchers have focused their ...attention on nanocrystals of noble metals and their controlled synthesis, characterization, and potential applications. Although the synthesis of various noble metal nanocrystals with different morphologies has been reported, most studies are limited to low-index facet-terminated nanocrystals. High-index facets, denoted by a set of Miller indices {hkl} with at least one index greater than unity, possess a high density of low-coordinated atoms, steps, edges, and kinks within these structures and serve as more active catalytic sites. With the potential for enhanced catalytic performance, researchers have used the insights from shape-controlled nanocrystal synthesis to construct noble metal nanocrystals bounded with high-index facets. Since the report of Pt tetrahexahedral nanocrystals, researchers have achieved significant progress and have prepared nanocrystals with various high-index facets. Because of the general order of surface energy for noble metals, high-index facets typically vanish faster in a crystal growth stage and are difficult to preserve on the surface of the final nanocrystals. Therefore researchers have had limited opportunities to examine high-indexed noble metal nanocrystals with a controlled morphology and investigate their resultant behaviors in depth. In this Account, we thoroughly discuss the basic concepts and state-of-the-art morphology control of some noble metal nanocrystals enclosed with high-index facets. We briefly introduce high-index facets from both crystallographic and geometrical points of view, both of which serve as methods to classify these high-index facets. Then, we summarize various typical noble metal nanocrystals terminated by different types of high-index facets, including {hk0} (h > k > 0), {hhl} (h > l > 0), {hkk} (h > k > 0), and {hkl} (h > k > l > 0). In each type, we describe several distinct morphologies including convex, concave, and other irregular shapes in detail. Based on these remarks, we discuss key factors that may induce the variations of Miller indices in each class, such as organic capping ligands and metallic cationic species. In a look at applications, we review several typical high-indexed noble metal nanocrystals showing enhanced electrocatalytic or chemical catalytic activities.
The control of multimetallic ensembles at the atomic‐level is challenging, especially for high‐entropy alloys (HEAs) possessing five or more elements. Herein, the one‐pot synthesis of ...hexagonal‐close‐packed (hcp) PtRhBiSnSb high‐entropy intermetallic (HEI) nanoplates with intrinsically isolated Pt, Rh, Bi, Sn, and Sb atoms is reported, to boost the electrochemical oxidation of liquid fuels. Taking advantage of these combined five metals, the well‐defined PtRhBiSnSb HEI nanoplates exhibit a remarkable mass activity of 19.529, 15.558, and 7.535 A mg−1Pt+Rh toward the electrooxidation of methanol, ethanol, and glycerol in alkaline electrolytes, respectively, representing a state‐of‐the‐art multifunctional electrocatalyst for alcohol oxidation reactions. In particular, the PtRhBiSnSb HEI achieves record‐high methanol oxidation reaction (MOR) activity in an alkaline environment. Theoretical calculations demonstrate that the introduction of the fifth metal Rh enhances the electron‐transfer efficiency in PtRhBiSnSb HEI nanoplates, which contributes to the improved oxidation capability. Meanwhile, robust electronic structures of the active sites are achieved due to the synergistic protections from Bi, Sn, and Sb sites. This work offers significant research advances in developing well‐defined HEA with delicate control over compositions and properties.
High‐entropy PtRhBiSnSb intermetallic nanoplates with intrinsically isolated Pt/Rh/Bi/Sn/Sb atoms are successfully constructed via a one‐pot method. Benefiting from the synergism of the chosen five elements, these well‐defined PtRhBiSnSb intermetallic nanoplates achieve ultrahigh performance toward the electrochemical oxidation of methanol, ethanol, and glycerol in alkaline electrolytes, emerging as a state‐of‐the‐art multifunctional electrocatalyst for the alcohol oxidation reactions.
Metal halide perovskites under compression Li, Qian; Zhang, Liming; Chen, Zhongwei ...
Journal of materials chemistry. A, Materials for energy and sustainability,
2019, Letnik:
7, Številka:
27
Journal Article
Recenzirano
Within the last ten years, the power conversion efficiencies of metal halide perovskite (MHP) solar cells have developed at an unprecedented rate to above ∼24%. The outstanding photoresponse features ...of MHPs make them promising materials in the photovoltaic field, opening a new chapter for energy conversion from solar power to electricity. Recently, the unique tool of high pressure has been applied to MHPs to optimize their physical properties and obtain an in-depth understanding of their structure-property relationships. High pressure studies on MHPs allow for the
in situ
and continuous tailoring of MHP structures and properties, which is not feasible using traditional chemical methods. More importantly, the underlying transition and engineering mechanisms, which are hidden at ambient conditions, are successfully revealed through high pressure treatment. In this review, we aim to comprehensively summarize the structure and property engineering of MHPs in the high pressure dimension. Systematic comparisons between MHP systems are expected to reveal the structure/property contributions of different components in MHPs. Our discussions on high pressure MHPs are expected to offer some new strategies for the further design and synthesis of MHPs with promising applications.
High pressure engineering of metal halide perovskites, revealing the structural and photovoltaic performance contributions of different components.
0D hybrid metal halides (0D HMHs) are considered to be promising luminescent emitters. 0D HMHs commonly exhibit self‐trapped exciton (STE) emissions originating from the inorganic metal halide anion ...units. Exploring and utilizing the emission features of the organic cation units in 0D HMHs is highly desired to enrich their optical properties as multifunctional luminescent materials. Here, tunable emissions from organic and inorganic units are successfully achieved in triphenylsulfonium (Ph3S+)‐based 0D HMHs. Notably, integrated afterglow and STE emissions with adjustable intensities are obtained in (Ph3S)2Sn1−xTexCl6 (x = 0–1) via the delicate combination of SnCl62− and TeCl62−. Moreover, such a strategy can be readily extended to develop other HMH materials with intriguing optical properties. As a demonstration, 0D (Ph3S)2Zn1−xMnxCl4 (x = 0–1) are constructed to achieve integrated afterglow and Mn2+ d–d emissions with high efficiency. Consequently, these novel 0D HMHs with colorful afterglow and STE emissions are applied in multiple anti‐counterfeiting applications.
A novel strategy is developed to modulate the afterglow and self‐trapped exciton (STE) emissions in 0D (Ph3S)2Sn1−xTexCl6 (x = 0–1) single crystals. Moreover, the integration of afterglow and STE emissions is realized in (Ph3S)2Sn0.92Te0.08Cl6. These as‐prepared 0D hybrid metal halides with colorful emissions are demonstrated for multiple anti‐counterfeiting and information storage applications.
Platinum is the most effective metal for a wide range of catalysis reactions, but it fails in the formic acid electrooxidation test and suffers from severe carbon monoxide poisoning. Developing ...highly active and stable catalysts that are capable of oxidizing HCOOH directly into CO2 remains challenging for commercialization of direct liquid fuel cells. A new class of PtSnBi intermetallic nanoplates is synthesized to boost formic acid oxidation, which greatly outperforms binary PtSn and PtBi intermetallic, benefiting from the synergism of chosen three metals. In particular, the best catalyst, atomically ordered Pt45Sn25Bi30 nanoplates, exhibits an ultrahigh mass activity of 4394 mA mg−1 Pt and preserves 78% of the initial activity after 4000 potential cycles, which make it a state‐of‐the‐art catalyst toward formic acid oxidation. Density functional theory calculations reveal that the electronic and geometric effects in PtSnBi intermetallic nanoplates help suppress CO* formation and optimize dehydrogenation steps.
Intermetallic PtSnBi nanoplates with tunable compositions are fabricated via a sequential “complexing–reducing–ordering” process in a one‐pot wet‐chemistry method. These Pt45Sn25Bi30 intermetallic nanoplates exhibit excellent electrocatalytic activity and outstanding long‐term stability toward the formic acid oxidation reaction, due to the efficient suppression of CO* formation and the optimization of dehydrogenation steps.
Tin-based nanomaterials have been of increasing interest in many fields such as alkali-ion batteries, gas sensing, thermoelectric devices, and solar cells. Finely controllable structures and ...compositions of tin-based nanomaterials are crucial to improve their performances. The solution-based colloidal synthesis of these compounds offers a promising path toward controlling their structures and components. This feature article summarizes the progress in recent studies on the colloidal synthesis of tin-based nanomaterials (such as metallic tin, alloys, oxides, chalcogenides, and phosphides) and their applications in alkali-ion batteries including our own recent contributions to this subject. The challenges and future outlook of the controllable synthesis and practical development of tin-based anode materials are also addressed.
This Feature Article summarizes the recent advances in the colloidal synthesis of tin-based nanomaterials and their electrochemical properties in alkali-ion batteries.
0D lead‐free metal halide nanocrystals (NCs) are an emerging class of materials with intriguing optical properties. Herein, colloidal synthetic routes are presented for the production of 0D Cs3Cu2X5 ...(X = I, Br, and Cl) NCs with orthorhombic structure and well‐defined morphologies. All these Cs3Cu2X5 NCs exhibit broadband blue‐green photoluminescence (PL) emissions in the range of 445–527 nm with large Stokes shifts, which are attributed to their intrinsic self‐trapped exciton (STE) emission characteristics. The high PL quantum yield of 48.7% is obtained from Cs3Cu2Cl5 NCs, while Cs3Cu2I5 NCs exhibit considerable air stability over 45 days. Intriguingly, as X is changed from I to Br and Cl, Cs3Cu2X5 NCs exhibit a continuous redshift of emission peaks, which is contrary to the blueshift in CsPbX3 perovskite NCs.
0D all‐inorganic Cs3Cu2X5 (X = I, Br, and Cl) nanocrystals (NCs) with orthorhombic structure and well‐defined morphologies are produced. The NCs exhibit a continuous redshift of broadband blue‐green photoluminescence emissions in the range of 445–527 nm as X is changed from I to Br and Cl, which are attributed to their intrinsic self‐trapped exciton emission characteristics.
Due to the increasing worldwide energy demand and environ-mental concerns, the need for alternative energy sources is growing stronger, and platinum catalysts in fuel cells may help make the ...technologies a reality. However, the pursuit of highly active Pt-based electrocatalysts continues to be a challenge. Scientists developing electrocatalysts continue to focus on characterizing and directing the construction of nanocrystals and advancing their electrochemical applications. Although chemists have worked on Pt-based bimetallic (Pt-M) preparations in the past, more recent research shows that both shape-controlled Pt-M nanocrystals and the assembly of these nanocrystals into supercrystals are promising new directions. A solution-based synthesis approach is an effective technique for preparing crystallographic facet-directed nanocatalysts. This is aided by careful selection of the metal precursor, capping ligand, reducing agent, and solvent. Incorporating a secondary metal M into the Pt lattice and manipulating the crystal facets on the surface cooperatively alter the electrocatalytic behavior of these Pt-M bimetallic nanocrystals. Specifically, chemists have extensively studied the {111}- and {100}-terminated crystal facets because they show unique atomic arrangement on surfaces, exhibit different catalytic performance, and possess specific resistance to toxic adsorbed carbon monoxide (COads). For catalysts to have maximum efficiency, they need to have resistance to COads and other poisonous carbon-containing intermediates when the catalysts operate under harsh conditions. A necessary design to any synthesis is to clearly understand and utilize the role of each component in order to successfully induce shape-controlled growth. Since chemists began to understand Pt nanocrystal shape-dependent electrocatalytic activity, the main obstacles blocking proton exchange membrane fuel cells are anode poisoning, sluggish kinetics at the cathode, and low activity. In this Account, we discuss the basic concepts in preparation of Pt-M bimetallic nanocrystals, focusing on several immaculate examples of manipulation at the nanoscale. We briefly introduce the prospects for applying Pt-M nanocrystals as electrocatalysts based on the electronic and geometric standpoints. In addition, we discuss several key parameters in the solution-based synthesis approach commonly used to facilitate Pt-M nanocrystals, such as reaction temperature and time, the combination of organic amines and acids, gaseous adsorbates, anionic species, and solvent. Each example features various nanoscale morphologies, such as spheres, cubes, octahedrons, and tetrahedrons. Additionally, we outline and review the superior electrocatalytic performances of the recently developed high-index Pt-M nanostructures. Next, we give examples of the electrocatalytic capabilities from these shape-defined Pt-M architectures by highlighting significant accomplishments in specific systems. Then, using several typical cases, we summarize electrochemical evaluations on the Pt-based shape-/composition-dependent nanocatalysts toward reactions on both the anode and the cathode. Lastly, we provide an outlook of current challenges and promising directions for shape-controlled Pt-M bimetallic electrocatalysts.
