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Recent years have witnessed a rapid development of the fluorescent carbon dots (CDs), due to their distinctive advantages of straightforward synthesis, excellent biocompatibility, low ...cost, and tunable optical properties. However, the widespread applications of CDs in biomedical theranostics, light harvesting, and photocatalysis are limited by the lack of emission and/or excitation in the red/near-infrared (NIR) region. Extensive explorations have been conducted to synthesize CDs with intensive red/NIR emission/excitation (red CDs) by rational design and ingenious synthesis to broaden their applications. This review emphasizes the most recent efforts in the development of CDs with intensive emission at a long wavelength, with a focus on the regulation methods for the optical properties of CDs, including particle size, surface state, and heteroatom doping. Key factors in processing red CDs, such as reaction solvent and precursors, are demonstrated. More importantly, employing polyaromatic and dye molecules as carbon sources is highlighted, which could further expand emission/excitation to the NIR region. The boosting applications of red CDs in white light-emitting diodes (WLEDs), biosensing, bioimaging, theranostics, and photocatalysis are demonstrated. Finally, the challenges and perspectives of red CDs are also discussed.
Diabetic ulcers are the second largest complication caused by diabetes mellitus. A great number of factors, including hyperchromic inflammation, susceptible microbial infection, inferior ...vascularization, the large accumulation of free radicals, and other poor healing-promoting microenvironments hold back the healing process of chronic diabetic ulcer in clinics. With the increasing clinical cases of diabetic ulcers worldwide, the design and development of advanced wound dressings are urgently required to accelerate the treatment of skin wounds caused by diabetic complications. Electrospinning technology has been recognized as a simple, versatile, and cost-reasonable strategy to fabricate dressing materials composed of nanofibers, which possess excellent extracellular matrix (ECM)-mimicking morphology, structure, and biological functions. The electrospinning-based nanofibrous dressings have been widely demonstrated to promote the adhesion, migration, and proliferation of dermal fibroblasts, and further accelerate the wound healing process compared with some other dressing types like traditional cotton gauze and medical sponges, etc. Moreover, the electrospun nanofibers are commonly harvested in the structure of nonwoven-like mats, which possess small pore sizes but high porosity, resulting in great microbial barrier performance as well as excellent moisture and air permeable properties. They also serve as good carriers to load various bioactive agents and/or even living cells, which further impart the electrospinning-based dressings with predetermined biological functions and even multiple functions to significantly improve the healing outcomes of different chronic skin wounds while dramatically shortening the treatment procedure. All these outstanding characteristics have made electrospun nanofibrous dressings one of the most promising dressing candidates for the treatment of chronic diabetic ulcers. This review starts with a brief introduction to diabetic ulcer and the electrospinning process, and then provides a detailed introduction to recent advances in electrospinning-based strategies for the treatment of diabetic wounds. Importantly, the synergetic application of combining electrospinning with bioactive ingredients and/or cell therapy was highlighted. The review also discussed the advantages of hydrogel dressings by using electrospun nanofibers. At the end of the review, the challenge and prospects of electrospinning-based strategies for the treatment of diabetic wounds are discussed in depth.
Acidic dissolution of transition metals from Pt based alloy catalysts for oxygen reduction reaction (ORR) is an unavoidable process during fuel cell operation. In this work we studied the effect of ...acid treatment of graphene-supported Pt1Ni x (x = 0, 0.25, 0.5, 1, and 2) alloys on the kinetics of the ORR in both alkaline and acidic solutions together with the generation of OH radicals in alkaline solutions. The alloy nanoparticles were synthesized through coimpregnation and chemical reduction. The electronic and structural features of the alloy were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The ORR performances were studied using cyclic voltammetry and rotating ring disk electrode techniques in 0.05 M H2SO4 and 0.1 M NaOH, respectively. The alloy catalysts were more active than pure Pt toward ORR, and after acid treatment the ORR activity of Pt−Ni alloy was enhanced in both acidic and alkaline media. The maximum activity of the Pt-based catalysts was found with ca. 50 atom % Ni content in the alloys (Pt1Ni1@graphene). OH radicals were generated through dissociation of hydroperoxide at the catalysts’ surface and detected by fluorescence technique using terephthalic acid as capture reagent, which readily reacts with OH radical to produce highly fluorescent product, 2-hydroxyterephthalic acid. More OH radicals were found to be generated at Pt1Ni1@graphene catalyst. This work may be valuable in the design of electrocatalysts with higher ORR activity but lower efficiency of OH radical generation.
A comparative study on bimetallic alloy nanomaterials, with different dimensions (i.e., 1D nanowires and 3D nanosponges), of peroxidase mimetics and as enhanced catalysts for oxygen reduction ...reaction was performed. The synthesized PdPt nanosponges possessed much better oxidase and peroxidase mimetics than those of PdPt nanowires. In addition, nanosponges exhibited more advantageous onset potential and higher ORR specific activity, while nanowires presented higher limiting current density.
•The peroxidase mimetics and ORR activity of PdPt NWs and NSs were investigated.•PdPt NSs possessed much better peroxidase mimetics than that of PdPt NWs.•PdPt NSs exhibited more advantageous onset potential and higher ORR activity.•PdPt NWs presented higher limiting current density.
An amperometric glucose biosensor based on the direct electron transfer (DET) of glucose oxidase (GOx) was developed and the enhanced catalytic current in presence of substrate was used to quantify ...glucose. GOx was adsorbed onto nanostructured ZnO modified indium tin oxide (ITO) electrodes. The goal of this work was to study the effects of morphology of nanostructured ZnO on DET of GOx and the sensor’s analytical properties. Nanostructured ZnO materials including nanorods (NRs) and nanoplates (NPs) were electrochemical deposited onto ITO and were characterized using scanning electron microscopy and X-ray diffraction. Through adjusting the precursor of Zn ions, electrolytes and controlling deposition charge (
Q, in Coulomb, C), different nanostructured ZnO with different size, shape and deposition density were obtained. GOx was adsorbed onto nanostructured ZnO via layer-by-layer assembling to form GOx and polylectrolyte multilayer films. Compared to bare ITO or ITO deposited with nanostructured ZnO with other morphologies, GOx immobilized onto ZnO NRs arrays (
Q
=
0.1 C) gave higher current signals, exhibited reversible DET (
k
s
, 2.16
s
−1), wide linear range (from 0.1 to 9
mM) with the limit of detection of 1.94
μM and low apparent Michaelis–Menten constant (
K
Mapp, 3.12
mM).
Graphene oxide (GO) obtained from chemical oxidation of flake graphite was derivatized with sulfonic groups to form sulfonic-functionalized GO (GO–SO
3
−) through four sulfonation routes: through ...amide formation between the carboxylic group of GO and amine of sulfanilic acid (AA–GO–SO
3
−), aryl diazonium reaction of sulfanilic acid (AD–GO–SO
3
−), amide formation between the carboxylic group of GO and amine of cysteamine and oxidation by H
2O
2 (CA–GO–SO
3
−), and alkyl diazonium reaction of cysteamine and oxidation by H
2O
2 (CD–GO–SO
3
−). Results of Fourier transform infrared spectroscopy and X-ray photoelectrospectrocopy showed that –SO
3
− groups were attached onto GO. Thermo gravimetric analysis showed that derivatization with sulfonic groups improved thermo stability of GO. X-ray diffraction results indicated that GO–SO
3
− had more ordered π–π stacking structure than the original GO. GO–SO
3
− and cationic polyelectrote, poly (diallyldimethylammoniumchloride) (PDDA) were adsorbed at indium tin oxide (ITO) glass surface through layer-by-layer assembling to form (GO–SO
3
−/PDDA)
n
/ITO multilayers. After tris-(2,2′-bipyridyl) ruthenium (II) dichloride (Ru(bpy)
3
2+) was incorporated into the multilayers, the obtained Ru(bpy)
3
2+/(GO–SO
3
−/PDDA)
n
/ITO electrodes can be used as electrochemiluminescence sensors for detection of organic amine with high sensitivity (limit of detection of 1
nM) and stability.
Aqueous N-rich carbon dots (CDs), prepared by the microwave-assisted pyrolysis method, are applied as a dual sensing platform for both the fluorescent and electrochemical detection of ...2,4,6-trinitrotoluene (TNT). The fluorescent sensing platform is established on the strong TNT–amino interaction which can quench the photoluminescence of amino functionalized CDs through charge transfer. The resultant linear detection ranges from 10 nM to 1.5 μM with a fast response time of 30 s. Glassy carbon electrode modified with CDs exhibits a fine capability for TNT reduction with the linear range from 5 nM to 30 μM, better than that obtained by the fluorescent method. Moreover, the minimum distinguishable response concentration with respect to these two methods is down to the nanomolar level with a high specificity and sensitivity.
The development of state‐of‐the‐art catalysts plays a crucial role in the fields of materials science and engineering for efficient energy conversion and storage. Although some excellent catalysts ...have been developed, considerable challenges remain to bring down the cost and increase the activity of catalysts. The emergence of carbon materials (i.e., activated carbon, graphite, fullerenes, carbon nanotubes, diamond, graphene, etc.) provides an excellent alternative to traditional catalysts. Considerable effort has been made to develop diverse carbon‐based catalysts, including carbon in itself, heteroatom‐doped carbon, carbon supported catalysts, carbon hybrids, and so on. Additionally, tremendous progress has been achieved in various catalysis fields, such as chemical synthesis, gas or oil desulfurization, biosensor, energy storage and conversion, organism photodegradation, etc. This article reviews the versatility of carbon family, and their endless catalytic properties and applications, from the viewpoint of materials and chemistry.
Back to carbon black: Considerable effort has been made to develop diverse carbon‐based catalysts, including carbon in itself, heteroatom‐doped carbon, carbon supported catalysts, carbon hybrids. Although some excellent catalysts have been developed, there are still some challenges in the cost and activity of catalysts.
Dual‐band electrochromism is a phenomenon where materials can independently regulate the transmittance of visible (VIS) and near‐infrared (NIR) light. Owing to their bistability, low energy ...consumption, and independent control over VIS and NIR regions, dual‐band electrochromic (EC) devices have been of great significance to fully harnessing VIS and NIR light and building an energy‐saving society. The past several years have witnessed the efforts put in developing novel EC materials to improve their dual‐band optical performance through altering their composition, structural, and physicochemical features, which determine the optical behavior of dual‐band EC devices. In this review, the concept, significance, working principle, and key influence factors of dual‐band electrochromism are briefly introduced. Next, the up‐to‐date progress of dual‐band EC materials including inorganic, organic, and composites materials are summarized, with a focus on material design, device fabrication, and performance optimization. Finally, the challenges and perspectives of dual‐band EC materials and devices are also presented.
A brief review of the most recent progress in dual‐band EC materials including inorganic and organic materials, and hybrid composites, in terms of mechanism discussion, performance optimization, future challenges, and perspectives, to inspire further research in the optimization of dual‐band EC devices and their practical application.
Constructing electrocatalysts with enhanced activity and stability is necessary due to the increasing demands of the fuel cell industry. This work demonstrates a facile approach to synthesize ...well-defined three-dimensional (3D) PtM (M = Fe, Co, Cu, Ni) bimetallic alloy nanosponges (BANs) in the presence of Al. Significantly, with the aid of Al, the as-prepared BANs exhibit greatly enhanced electrochemistry catalytic activity in an oxygen reduction reaction (ORR), and PtFe BANs appear the best ORR property among the four BANs and commercial Pt/C catalysts. This work may provide a universal approach for convenient and large-scale fabrication of porous bimetallic nanocatalysts, thus providing promising potential application as an efficient cathodic component in fuel cells for industrial production.
