Abstract3D printing is becoming an efficient approach to facilely and accurately fabricate diverse complex architectures with broad applications. However, suitable inks and 3D print favorable architectures with high electrochemical performances for energy storage are still being explored. Here, sulfur copolymer‐graphene architectures with well‐designed periodic microlattices are 3D printed as a cathode for Li‐S batteries using a suitable ink composed of sulfur particles, 1,3‐diisopropenylbenzene (DIB), and condensed graphene oxide dispersion. Using thermal treatment, elemental sulfur can be reacted with DIB to produce sulfur copolymer, which can partially suppress the dissolution of polysulfides. Moreover, graphene in the architecture can provide high electrical conductivity for whole electrode. Hence, 3D printed sulfur copolymer‐graphene architecture exhibits a high reversible capacity of 812.8 mA h g−1 and good cycle performance. Such a simple 3D printing approach can be further extended to construct many complex architectures for various energy storage devices.
exhibited a modest areal energy density (<10 µWh cm −2 ). [5a] Thus, it is still a big challenge to efficiently and cost effectively fabricate asymmetric MSCs with high areal energy densities.Very recently, extrusion-based 3D printing, as an emerging technology, has been successfully demonstrated to construct complex structures with a wide application in various areas, such as electronic, [7] biomedical, [8] and energy storage fields. [9] To develop suitable inks with high viscosities and shear-thinning rheological properties, it is essential to print ideal architectures without collapse. During the printing process, the functional inks were extruded through nozzle and directly printed on substrates layer by layer in the vertical dimension. [10] To date, although 3D printing has been explored to build electrochemical architectures for lithium-sulfur batteries, [11] lithium-ion microbatteries, [12] and symmetric MSCs, [13] it is still in the initial stage to 3D print desirable devices with high electrochemical performances for energy storage applications.Here, we demonstrate that an asymmetric MSC with ultrahigh areal energy density can be facilely and precisely realized by the 3D printing technology. In a typical procedure, the cathode and anode inks are composed of vanadium pentoxide (V 2 O 5 ) and graphene-vanadium nitride quantum dots (G-VNQDs) with highly concentrated graphene oxide (GO) dispersions, respectively. The 3D printed asymmetric MSC with interdigitated electrodes exhibits excellent structural integrity, a large areal mass loading of 3.1 mg cm −2 , and a wide electrochemical potential window of 1.6 V. Moreover, there are substantial open macropores in the 3D printed electrodes, which can serve as numerous channels for accelerating the mass transportation. These features enable the 3D printed asymmetric MSC to have an ultrahigh areal energy density of 73.9 µWh cm −2 and power density of 3.77 mW cm −2 as well as a long cycle life up to 8000 cycles. Figure 1 illustrates the 3D printing procedures of the asymmetric MSC with interdigitated electrodes. The cathode (V 2 O 5 ) and anode (G-VNQDs) active materials were first synthesized according to our previously reported protocols (for details, see Supporting Information). [14] V 2 O 5 is considered as one promising cathode material due to its high Faradic activity and natural abundance, and VN is used as one anode materials owing to its large pseudocapacitance as well as appropriate negative operating potential. [15] Subsequently, cathode or anode ink was A 3D printing approach is first developed to fabricate quasi-solid-state asymmetric micro-supercapacitors to simultaneously realize the efficient patterning and ultrahigh areal energy density. Typically, cathode, anode, and electrolyte inks with high viscosities and shear-thinning rheological behaviors are first prepared and 3D printed individually on the substrates. The 3D printed asymmetric micro-supercapacitor with interdigitated electrodes exhibits excellent structural integrity, a large areal ...
Covalent triazine-based frameworks (CTFs), a group of semiconductive polymers, have been identified for photocatalytic water splitting recently. Their adjustable band gap and facile processing offer great potential for discovery and development. Here, we present a series of CTF-0 materials fabricated by two different approaches, a microwave-assisted synthesis and an ionothermal method, for water splitting driven by visible-light irradiation. The material (CTF-0-M 2 ) synthesized by microwave technology shows a high photocatalytic activity for hydrogen evolution (up to 7010 μmol h −1 g −1 ), which is 7 times higher than another (CTF-0-I) prepared by conventional ionothermal trimerization under identical photocatalytic conditions. This leads to a high turnover number (TON) of 726 with respect to the platinum cocatalyst after seven cycles under visible light. We attribute this to the narrowed band gap, the most negative conduction band, and the rapid photogenerated charge separation and transfer. On the other hand, the material prepared by the ionothermal method is the most efficient one for oxygen evolution. CTF-0-I initially produces ca. 6 times greater volumes of oxygen gas than CTF-0-M 2 under identical experimental conditions. CTF-0-I presents an apparent quantum efficiency (AQY) of 5.2% at 420 nm for oxygen production without any cocatalyst. The activity for water oxidation exceeds that of most reported CTFs due to a large driving force for oxidation and a large number of active sites. Our findings indicate that the band positions and the interlayer stacking structures of CTF-0 were modulated by varying synthesis conditions. These modulations impact the optical and redox properties, resulting in an enhanced performance for photocatalytic hydrogen and oxygen evolution, confirmed by firstprinciples calculations.
high-performance photodetection is highly desirable in various fields, including optical communication, imaging, and environmental monitoring. [4][5][6] Currently, GaN, Si, InGaAs, and other semiconductors have dominated the ultraviolet to near-infrared photodetection market. [7][8][9][10] These detectors are mostly assembled on rigid substrates and usually require relatively thick active materials for photonic detection, therefore, they are not compatible with flexible systems or suitable for low cost manufacturing.The demand for flexible devices has driven the research in emerging functional materials that are bendable. To date, various functional materials have been explored for constructing flexible photodetectors, such as zero-dimensional (0D) semiconductor nanostructures, 2D layered materials, and perovskites. [11][12][13][14] They can be facilely transferred to arbitrary rigid substrates and directly deposited on flexible substrates, which are favorable for flexible optoelectronics. Particularly, organometal halide perovskites (OHPs) have demon strated intriguing properties, including large absorption coefficients, tunable bandgaps, long carrier diffusion length, and high carrier mobility. [15][16][17][18][19][20] Nevertheless, their organic parts Flexible devices are garnering substantial interest owing to their potential for wearable and portable applications. Here, flexible and self-powered photodetector arrays based on all-inorganic perovskite quantum dots (QDs) are reported. CsBr/KBr-mediated CsPbBr 3 QDs possess improved surface morphology and crystallinity with reduced defect densities, in comparison with the pristine ones. Systematic material characterizations reveal enhanced carrier transport, photoluminescence efficiency, and carrier lifetime of the CsBr/KBr-mediated CsPbBr 3 QDs. Flexible photodetector arrays fabricated with an optimum CsBr/KBr treatment demonstrate a high open-circuit voltage of 1.3 V, responsivity of 10.1 A W −1 , specific detectivity of 9.35 × 10 13 Jones, and on/off ratio up to ≈10 4 . Particularly, such performance is achieved under the self-powered operation mode. Furthermore, outstanding flexibility and electrical stability with negligible degradation after 1600 bending cycles (up to 60°) are demonstrated. More importantly, the flexible detector arrays exhibit uniform photoresponse distribution, which is of much significance for practical imaging systems, and thus promotes the practical deployment of perovskite products.The "Internet of Things" (IoT) has been expected to reshape or even revolutionize human daily lives. As a fundamental technology of the IoT, flexible optoelectronics, such as solar power sources, display panels, and photodetectors, have attracted substantial research interest globally. [1][2][3] Moreover,
Sulfur is easy to be incorporated into ZnO nanoparticles by the solution-combustion method. Herein, the magnetic and adsorption properties of a series of ZnOS (x = 0, 0.05, 0.1, 0.15, and 0.2) nanoparticles were systematically investigated. The X-ray diffraction patterns show that the as-prepared ZnOS nanoparticles have the hexagonal wurtzite structure of ZnO with a low sulfur content that gradually transforms into the zinc blende structure of ZnS when the x value is greater than 0.1. PL spectra show several bands due to different transitions, which have been explained by the recombination of free excitons or defect-induced transitions. The introduction of sulfur not only modifies the bandgap of ZnO, but also impacts the concentration of Zn vacancies. The as-prepared ZnO shows weak room-temperature ferromagnetism, and the incorporation of sulfur improves the ferromagnetism owing to the increased concentration of Zn vacancies, which may be stabilized by the doped sulfur ions. The adsorption capability of ZnOS nanoparticles has been significantly improved, and the process can be well described by the pseudo-first-order kinetic model and the Freundlich isotherm model. The mechanism has been confirmed to be due to the active sulfate groups existing in zinc oxysulfide nanoparticles.
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