The authors provide at a look at the biological applications of supramolecular assemblies that have been designed for excitation energy transfer. The topics discussed include biosensors and ...bioimaging.
Semiconductor nanowires are attracting intense interest as a promising material for solar energy conversion for the new‐generation photovoltaic (PV) technology. In particular, silicon nanowires ...(SiNWs) are under active investigation for PV applications because they offer novel approaches for solar‐to‐electric energy conversion leading to high‐efficiency devices via simple manufacturing. This article reviews the recent developments in the utilization of SiNWs for PV applications, the relationship between SiNW‐based PV device structure and performance, and the challenges to obtaining high‐performance cost‐effective solar cells.
Silicon nanowires (SiNWs) are attracting intense interest as a promising material for solar energy conversion for the new‐generation photovoltaic (PV) technology. This article reviews recent developments in the utilization of SiNWs for PV applications, the relationship between SiNW‐based PV device structure and performance, and the challenges to obtaining high‐performance cost‐effective solar cells.
To meet the requirements of potential applications, it is of great importance to explore new catalysts for formic acid oxidation that have both ultra-high mass activity and CO resistance. Here, we ...successfully synthesize atomically dispersed Rh on N-doped carbon (SA-Rh/CN) and discover that SA-Rh/CN exhibits promising electrocatalytic properties for formic acid oxidation. The mass activity shows 28- and 67-fold enhancements compared with state-of-the-art Pd/C and Pt/C, respectively, despite the low activity of Rh/C. Interestingly, SA-Rh/CN exhibits greatly enhanced tolerance to CO poisoning, and Rh atoms in SA-Rh/CN resist sintering after long-term testing, resulting in excellent catalytic stability. Density functional theory calculations suggest that the formate route is more favourable on SA-Rh/CN. According to calculations, the high barrier to produce CO, together with the relatively unfavourable binding with CO, contribute to its CO tolerance.
Exploring of new catalyst activation principle holds a key to unlock catalytic powers of cheap and earth‐abundant materials for large‐scale applications. In this regard, the vacancy defects have been ...proven to be effective to initiate catalytic active sites and endow high electrocatalytic activities. However, such electrocatalytically active defects reported to date have been mostly formed by anion vacancies. Herein, it is demonstrated for the first time that iron cation vacancies induce superb water splitting bifunctionality in alkaline media. A simple wet‐chemistry method is developed to grow ultrathin feroxyhyte (δ‐FeOOH) nanosheets with rich Fe vacancies on Ni foam substrate. The theoretical and experimental results confirm that, in contrast to anion vacancies, the formation of rich second neighboring Fe to Fe vacancies in δ‐FeOOH nanosheets can create catalytic active centers for both hydrogen and oxygen evolution reactions. The atomic level insight into the new catalyst activation principle based on metal vacancies is adaptable for developing other transition metal electrocatalysts, including Fe‐based ones.
Ultrathin feroxyhyte (δ‐FeOOH) nanosheets with rich Fe‐vacancies on Ni foam are synthesized, based on which an iron‐vacancy‐based catalyst activation principle to induce water‐splitting bifunctionality is proposed. Theoretical studies confirm that the formation of the second neighboring Fe to Fe vacancies in δ‐FeOOH nanosheets can create active centers for both hydrogen and oxygen evolution reactions.
Natural product analysis has gained wide attention in recent years, especially for herbal medicines, which contain complex ingredients and play a significant clinical role in the therapy of numerous ...diseases. The constituents of natural products are usually found at low concentrations, and the matrices are complex. Thus, the extraction of target compounds from natural products before analysis by analytical instruments is very significant for human health and its wide application. The commonly used traditional extraction methods are time‐consuming, using large amounts of sample and organic solvents, as well as expensive and inefficient. Recently, microextraction techniques have been used for natural product extraction to overcome the disadvantages of conventional extraction methods. In this paper, the successful applications of and recent developments in microextraction techniques including solvent‐based and sorbent‐based microextraction methods, in natural product analysis in recent years, especially in the last 5 years, are reviewed for the first time. Their features, advantages, disadvantages, and future development trends are also discussed.
Development of stimuli‐responsive materials with complex practical functions is significant for achieving bioinspired artificial intelligence. It is challenging to fabricate stimuli‐responsive ...hydrogels showing simultaneous changes in fluorescence color, brightness, and shape in response to a single stimulus. Herein, a bilayer hydrogel strategy is designed by utilizing an aggregation‐induced emission luminogen, tetra‐(4‐pyridylphenyl)ethylene (TPE‐4Py), to fabricate hydrogels with the above capabilities. Bilayer hydrogel actuators with the ionomer of poly(acrylamide‐r‐sodium 4‐styrenesulfonate) (PAS) as a matrix of both active and passive layers and TPE‐4Py as the core function element in the active layer are prepared. At acidic pH, the protonation of TPE‐4Py leads to fluorescence color and brightness changes of the actuators and the electrostatic interactions between the protonated TPE‐4Py and benzenesulfonate groups of the PAS chains in the active layer cause the actuators to deform. The proposed TPE‐4Py/PAS‐based bilayer hydrogel actuators with such responsiveness to stimulus provide insights in the design of intelligent systems and are highly attractive material candidates in the fields of 3D/4D printing, soft robots, and smart wearable devices.
Bioinspired hydrogels with abilities of simultaneous fluorescence color and brightness changes, as well as complex shape deformation under pH stimulus by utilizing aggregation‐induced emission luminogens (AIEgens) and the bilayer hydrogel technique are designed and fabricated.
Nonlinear optical microscopy has become a powerful tool in bioimaging research due to its unique capabilities of deep optical sectioning, high‐spatial‐resolution imaging, and 3D reconstruction of ...biological specimens. Developing organic fluorescent probes with strong nonlinear optical effects, in particular third‐harmonic generation (THG), is promising for exploiting nonlinear microscopic imaging for biomedical applications. Herein, a simple method for preparing organic nanocrystals based on an aggregation‐induced emission (AIE) luminogen (DCCN) with bright near‐infrared emission is successfully demonstrated. Aggregation‐induced nonlinear optical effects, including two‐photon fluorescence (2PF), three‐photon fluorescence (3PF), and THG, of DCCN are observed in nanoparticles, especially for crystalline nanoparticles. The nanocrystals of DCCN are successfully applied for 2PF microscopy at 1040 nm NIR‐II excitation and THG microscopy at 1560 nm NIR‐II excitation, respectively, to reconstruct the 3D vasculature of the mouse cerebral vasculature. Impressively, the THG microscopy provides much higher spatial resolution and brightness than the 2PF microscopy and can visualize small vessels with diameters of ≈2.7 µm at the deepest depth of 800 µm in a mouse brain. Thus, this is expected to inspire new insights into the development of advanced AIE materials with multiple nonlinearity, in particular THG, for multimodal nonlinear optical microscopy.
Aggregation‐induced nonlinear optical effects, in particular third‐harmonic generation, of an aggregation‐induced emission luminogen (AIEgen) are observed in nanoparticles, especially for crystalline nanoparticles. AIEgen nanocrystals enable ultradeep intravital third‐harmonic generation imaging (up to 800 µm) of mouse cerebral vasculature with high spatial resolution (≈2.7 µm) at the deepest depth of 800 µm, much superior to two‐ and three‐photon fluorescence imaging.
Novel 3D Ni1−xCoxSe2 mesoporous nanosheet networks with tunable stoichiometry are successfully synthesized on Ni foam (Ni1−xCoxSe2 MNSN/NF with x ranging from 0 to 0.35). The collective effects of ...special morphological design and electronic structure engineering enable the integrated electrocatalyst to have very high activity for hydrogen evolution reaction (HER) and excellent stability in a wide pH range. Ni0.89Co0.11Se2 MNSN/NF is revealed to exhibit an overpotential (η10) of 85 mV at −10 mA cm−2 in alkaline medium (pH 14) and η10 of 52 mV in acidic solution (pH 0), which are the best among all selenide‐based electrocatalysts reported thus far. In particular, it is shown for the first time that the catalyst can work efficiently in neutral solution (pH 7) with a record η10 of 82 mV for all noble metal‐free electrocatalysts ever reported. Based on theoretical calculations, it is further verified that the advanced all‐pH HER activity of Ni0.89Co0.11Se2 is originated from the enhanced adsorption of both H+ and H2O induced by the substitutional doping of cobalt at an optimal level. It is believed that the present work provides a valuable route for the design and synthesis of inexpensive and efficient all‐pH HER electrocatalysts.
An integrated electrocatalyst comprising 3D mesoporous Ni0.89Co0.11Se2 nanosheet networks on Ni foam is synthesized, and it demonstrates very high activities and excellent stabilities for hydrogen evolution reaction (HER) in all‐pH conditions. Theoretical calculations verify that electronic structure engineering by optimal Co doping enhances the adsorption of H+ and H2O, leading to the advanced all‐pH HER activity of the catalyst.
Single-atom catalysts not only maximize metal atom efficiency, they also display properties that are considerably different to their more conventional nanoparticle equivalents, making them a ...promising family of materials to investigate. Herein we developed a general host-guest strategy to fabricate various metal single-atom catalysts on nitrogen-doped carbon (M
/CN, M = Pt, Ir, Pd, Ru, Mo, Ga, Cu, Ni, Mn). The iridium variant Ir
/CN electrocatalyses the formic acid oxidation reaction with a mass activity of 12.9 Formula: see text whereas an Ir/C nanoparticle catalyst is almost inert (~4.8 × 10
Formula: see text). The activity of Ir
/CN is also 16 and 19 times greater than those of Pd/C and Pt/C, respectively. Furthermore, Ir
/CN displays high tolerance to CO poisoning. First-principle density functional theory reveals that the properties of Ir
/CN stem from the spatial isolation of iridium sites and from the modified electronic structure of iridium with respect to a conventional nanoparticle catalyst.
Metal‐assisted chemical etching (MacEtch) of silicon in oxidizing hydrofluoric acid (HF) solutions has emerged as a prominent top‐down micro/nanofabrication approach for a wide variety of silicon ...micro/nanostructures. The popularity of the process is due to its simplicity, rapidity, versatility, and scalability. In recent years, there has been a surge of interest in developing MacEtch silicon micro/nanostructures for advanced energy conversion and storage applications, such as photovoltaic devices, thermoelectric devices, lithium‐ion rechargeable batteries, and supercapacitors. Particularly, MacEtch has emerged as a powerful surface micro/nanostructuring method for low‐cost and scalable production of commercial black silicon (b‐Si) with excellent light trapping properties. This review on MacEtch processing of silicon in oxidizing HF solutions provides a critical description of its history and origin including how it evolved into what it is today, the understanding of its mechanism and important technical advances in the field. As regards MacEtch‐fabricated b‐Si, its initial discovery and further improvements to its large‐scale deployment in silicon photovoltaic industry are traced. Some fundamental challenges and perspectives in this exciting field are also discussed.
Metal‐assisted chemical etching of silicon in oxidizing hydrofluoric acid solutions is attracting considerable interest as an emerging top‐down micro/nanofabrication approach owing to its simplicity, rapidity, versatility, and scalability. This article reviews its development, mechanism, and advances in fabrication techniques, and highlights its development for black silicon solar cell applications.
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