Metal halide perovskites represent a flourishing area of research, driven by both their potential application in photo-voltaics and optoelectronics, and for the fundamental science underpinning their unique optoelectronic properties. The advent of colloidal methods for the synthesis of halide perovskite nanocrystals has brought to the attention inter-esting aspects of this new type of materials, above all their defect-tolerance. This review aims to provide an updated survey of this fast-moving field, with a main focus on their colloidal synthesis. We examine the chemistry and the ca-pability of different colloidal synthetic routes to control the shape, size and optical properties of the resulting nano-crystals. We also provide an up to date overview of their post-synthesis transformations, and summarize the various so-lution processes aimed at fabricating halide perovskite-based nanocomposites. We then review the fundamental optical properties of halide perovskite nanocrystals, by focusing on their linear optical properties, on the effects of quantum confinement and, then, on the current knowledge of their exciton binding energies. We also discuss the emergence of non-linear phenomena such as multiphoton absorption, biexcitons and carrier multiplication. At last, we provide an outlook in the field, with the most cogent open questions and possible future directions.

Metal Halide Perovskite Nanocrystals: Synthesis, Post-Synthesis Modifications and Their Optical Properties

Metal halide perovskites represent a flourishing area of research, which is driven by both their potential application in photovoltaics and optoelectronics and by the fundamental science behind their unique optoelectronic properties. The emergence of new colloidal methods for the synthesis of halide perovskite nanocrystals, as well as the interesting characteristics of this new type of material, has attracted the attention of many researchers. This review aims to provide an up-to-date survey of this fast-moving field and will mainly focus on the different colloidal synthesis approaches that have been developed. We will examine the chemistry and the capability of different colloidal synthetic routes with regard to controlling the shape, size, and optical properties of the resulting nanocrystals. We will also provide an up-to-date overview of their postsynthesis transformations, and summarize the various solution processes that are aimed at fabricating halide perovskite-based nanocomposites. Furthermore, we...

Metal Halide Perovskite Nanocrystals: Synthesis, Post-Synthesis Modifications, and Their Optical Properties.

As a new class of crystalline porous materials, metal-organic frameworks (MOFs) have received great attention owing to their unique advantages of ultrahigh surface area, large pore volume and versatile applications. Developing different strategies to control the morphology and size of MOFs is very important for their practical applications. Recently, micro/nanosized MOFs have been regarded as promising candidates for electrode materials with excellent performances, which not only bridge the gap between fundamental MOF science and forward-looking applications, but also provide an opportunity to make clear the relationship between morphologies and properties. This review focuses on the design and fabrication of one-, two- and three-dimensional MOFs at micro/nanoscale, and their direct applications in batteries, supercapacitors and electrocatalysis. A discussion on challenges and future prospects of the synthesis and electrochemical applications of micro/nanoscaled MOF materials is presented.

Synthesis of micro/nanoscaled metal-organic frameworks and their direct electrochemical applications.

Rechargeable aqueous zinc-ion batteries have been considered as a promising candidate for next-generation batteries. However, the formation of zinc dendrites are the most severe problems limiting their practical applications. To develop stable zinc metal anodes, a synergistic method is presented that combines the Cu-Zn solid solution interface on a copper mesh skeleton with good zinc affinity and a polyacrylamide electrolyte additive to modify the zinc anode, which can greatly reduce the overpotential of the zinc nucleation and increase the stability of zinc deposition. The as-prepared zinc anodes show a dendrite-free plating/stripping behavior over a wide range of current densities. The symmetric cell using this dendrite-free anode can be cycled for more than 280 h with a very low voltage hysteresis (93.1 mV) at a discharge depth of 80 %. The high capacity retention and low polarization are also realized in Zn/MnO2 full cells.

The Three-Dimensional Dendrite-Free Zinc Anode on a Copper Mesh with a Zinc-Oriented Polyacrylamide Electrolyte Additive

Isolated atoms featuring unique reactivity are at the heart of enzymatic and homogeneous catalysts. In contrast, although the concept has long existed, single-atom heterogeneous catalysts (SACs) have only recently gained prominence. Host materials have similar functions to ligands in homogeneous catalysts, determining the stability, local environment, and electronic properties of isolated atoms and thus providing a platform for tailoring heterogeneous catalysts for targeted applications. Within just a decade, we have witnessed many examples of SACs both disrupting diverse fields of heterogeneous catalysis with their distinctive reactivity and substantially enriching our understanding of molecular processes on surfaces. To date, the term SAC mostly refers to late transition metal-based systems, but numerous examples exist in which isolated atoms of other elements play key catalytic roles. This review provides a compositional encyclopedia of SACs, celebrating the 10th anniversary of the introduction of this term. By defining single-atom catalysis in the broadest sense, we explore the full elemental diversity, joining different areas across the whole periodic table, and discussing historical milestones and recent developments. In particular, we examine the coordination structures and associated properties accessed through distinct single-atom-host combinations and relate them to their main applications in thermo-, electro-, and photocatalysis, revealing trends in element-specific evolution, host design, and uses. Finally, we highlight frontiers in the field, including multimetallic SACs, atom proximity control, and possible applications for multistep and cascade reactions, identifying challenges, and propose directions for future development in this flourishing field.

Single-Atom Catalysts across the Periodic Table.

Ruthenium@N-doped graphite carbon derived from carbon foam for efficient hydrogen evolution reaction

To enhance the stability in humidity is very crucial to hybrid organic-inorganic lead halide perovskites in a broad range of applications. This report describes a coating stratergy of perovskite nanocrystals via polymethylmethacrylate-introduced ligand-assisted reprecipitation, using the interactions between the Pb cations on the surface of perovskite nanocrystals and the functional ester carbonyl groups in polymethylmethacrylate framework. The hydrophobic framework shields the open metal sites of hybrid organic-inorganic lead halide perovskites from being attacked by water, effectively retarding the diffusion of water into the perovskite nanocrystals. The as-prepared films demonstrate high resistance to heat and moisture. Additionally, the introduction of polymethylmethacrylate into ligand-assisted reprecipitation can effectively control the bulk precipitation and promote the stability of the perovskite solution.

/pdf/a-stable-lead-halide-perovskite-nanocrystals-protected-by-57p5nrs935.pdf

A stable lead halide perovskite nanocrystals protected by PMMA

Domoic acid (DA) is a naturally occurring neurotoxin known to bioaccumulate in marine products. Despite its hypertoxicity, the enrichment and analysis of trace DA in complex marine organisms remains a challenge. We describe herein the fabrication of a postsynthetic-modified magnetic zeolite imidazolate framework-8 (Fe3O4 SPs@ZIF-8/Zn2+), based on Fe3O4 superparticles, for the adsorption of DA from complex biological matrices. The adsorption of DA is rapid (∼5 min) and occurs through strong electrostatic interactions and chelation with coordinatively unsaturated zinc sites on the surface of Fe3O4 SPs@ZIF-8/Zn2+. Employing our Fe3O4 SPs@ZIF-8/Zn2+ sorbent in a magnetic solid-phase extraction, followed by liquid chromatographic separation and tandem mass spectrometric detection, resulted in a facile, rapid, efficient, and sensitive method for the enrichment and detection of trace DA in marine products. After optimization, this method yielded satisfactory precision (relative standard deviation ≤3.4%; n = 5) with a high degree of linearity from 1.0 to 1000.0 pg mL-1 ( r2 = 0.9997) and a detection limit of 0.2 pg mL-1 (S/N = 3). Recoveries of 93.1-102.3% were obtained in spiked aquatic products. In addition, trace levels of DA (49.2 pg mL-1) were found in shellfish samples, confirming the applicability of our Fe3O4 SPs@ZIF-8/Zn2+ adsorbent for the detection of DA in seafood.

Effective Extraction of Domoic Acid from Seafood Based on Postsynthetic-Modified Magnetic Zeolite Imidazolate Framework-8 Particles

Bacterial infectious diseases, such as sepsis, can lead to impaired function in the lungs, kidneys, and other vital organs. Although established technologies have been designed for the extracorporeal removal of bacteria, a high flow velocity of the true bloodstream might result in low capture efficiency and prevent the realization of their full clinical potential. Here, we develop a dialyzer made by three-dimensional carbon foam pre-grafted with nanowires to isolate bacteria from unprocessed blood. The tip region of polycrystalline nanowires is bent readily to form three-dimensional nanoclaws when dragged by the molecular force of ligand-receptor, because of a decreasing Young's moduli from the bottom to the tip. The bacterial capture efficiency was improved from ~10% on carbon foam and ~40% on unbendable single-crystalline nanowires/carbon foam to 97% on bendable polycrystalline nanowires/carbon foam in a fluid bloodstream of 10 cm s-1 velocity.

/pdf/bacterial-capture-efficiency-in-fluid-bloodstream-improved-lq7m9e5162.pdf

Bacterial capture efficiency in fluid bloodstream improved by bendable nanowires.

N6-methyladenine (m6A), one of the most common chemical modifications of eukaryotic RNA, participates in many important biological processes. An effective strategy for the quantitative determination of m6A is of great significance. Herein, we used methylated microRNA-21 (miRNA21) as the model target to propose a simple and sensitive electrogenerated chemiluminescence (ECL) biosensing platform to detect a specific m6A RNA sequence. This strategy is based on the fact that the anti-m6A-antibody can specifically recognize and bind to the m6A site in the RNA sequence, resulting in a quenching effect between Ru(bpy)32+-functionalized metal-organic frameworks and ferrocene. Luminescent metal-organic frameworks (Ru@MOFs) not only act as ECL indicators but also serve as nanoreactors for the relative ECL reactions owing to their porous or multichannel structure, which overcomes the fact that Ru(bpy)32+ is easily released when used for aqueous-phase detection, thus enhancing the ECL efficiency. Moreover, the ECL method has fewer modification steps and uses only one antibody to recognize the target RNA sequence, which simplifies the operation process and reduces the detection time, presenting a wide linear range (0.001-10 nM) for m6A RNA determination with a low detection limit (0.0003 nM). Additionally, this developed strategy was validated for m6A RNA detection in human serum. Thus, the ECL biosensing method provides a new method for m6A RNA determination that is simple, highly specific, and sensitive.

Signal-Off Electrogenerated Chemiluminescence Biosensing Platform Based on the Quenching Effect between Ferrocene and Ru(bpy)32+-Functionalized Metal-Organic Frameworks for the Detection of Methylated RNA.

Xuezhi Qiao

Papers

Ruthenium@N-doped graphite carbon derived from carbon foam for efficient hydrogen evolution reaction

A stable lead halide perovskite nanocrystals protected by PMMA

Effective Extraction of Domoic Acid from Seafood Based on Postsynthetic-Modified Magnetic Zeolite Imidazolate Framework-8 Particles

Bacterial capture efficiency in fluid bloodstream improved by bendable nanowires.

Signal-Off Electrogenerated Chemiluminescence Biosensing Platform Based on the Quenching Effect between Ferrocene and Ru(bpy)32+-Functionalized Metal-Organic Frameworks for the Detection of Methylated RNA.