A 3D N‐doped graphene foam with a 6.8 at% nitrogen content is prepared by annealing a freeze‐dried graphene oxide foam in ammonia. It is used as an anode in sodium ion batteries to deliver a high ...initial reversible capacity of 852.6 mA h g‐1 at 1 C between 0.02 and 3 V with a long‐term retention of 69.7% after 150 cycles.
It is critical for fabricating ultrasensitive biosensors to realize real-time in situ monitoring of superoxide anions (O2•−), a typical reactive oxygen species (ROS) that plays critical roles in ...diverse signaling pathways. Here, a simple on-step strategy was developed for morphology-controllable synthesis of manganese-organic framework (Mn-MOF) toward the enhanced sensing performance of O2•−. Interestingly, by delicately tuning the ratios of solvents to regulate initial concentrations of precursors, Mn-MOF nanoparticles, asymmetric nanolollipops and nanorods all with homogeneous components were prepared. As expected, Mn-MOF nanolollipops outperform other nanostructures in O2•− sensing due to their larger active surface areas which can attribute to their excellent dispersibility provided by the asymmetric structure, and the faster electron transfer rate promoted by the stem. Using the Mn-MOF nanolollipops-based O2•− biosensor, a high sensitivity of 105 μA cm−2 μM−1 is achieved, and the real-time in situ detection of O2•− released from living cells was successfully realized. This work holds a great potential in the exploration of O2•−-related biological processes in vivo, while offering deep scientific insights for solvents engineered morphologies of other MOF nanomaterials.
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Nanohoneycomb‐like strongly coupled CoMoO4‐3D graphene hybird electrodes are synthesized for supercapacitors which exhibit excellent specific capacitance and superior long‐term cycle stability. The ...supercapacitor device can power a 5 mm‐diameter LED efficiently for more than 3 min with a charging time of only 2 s, and shows high energy densities and good cycle stability.
Organometal trihalide perovskite based solar cells have exhibited the highest efficiencies to‐date when incorporated into mesostructured composites. However, thin solid films of a perovskite absorber ...should be capable of operating at the highest efficiency in a simple planar heterojunction configuration. Here, it is shown that film morphology is a critical issue in planar heterojunction CH3NH3PbI3‐xClx solar cells. The morphology is carefully controlled by varying processing conditions, and it is demonstrated that the highest photocurrents are attainable only with the highest perovskite surface coverages. With optimized solution based film formation, power conversion efficiencies of up to 11.4% are achieved, the first report of efficiencies above 10% in fully thin‐film solution processed perovskite solar cells with no mesoporous layer.
The critical role of perovskite morphology in planar heterojunction perovskite solar cells is probed and understood. Dewetting of perovskite films is minimized, to achieve uniform 100% coverage perovskite layers. Solution cast planar heterojunction solar cells with efficiencies of up to 11.4% are fabricated, a new record for such cells with no mesoporous layer.
A 12.6% Cu2ZnSnSxSe4–x (CZTSSe) solar cell is presented with detailed device characteristics. Both short‐circuit current density (Jsc) and open circuit voltage (Voc) increase in the 12.6% champion, ...relative to previous devices, due to better bulk CZTSSe quality and improved optical architecture. The reduction in Voc deficit shows opportunities to push CZTSSe solar cells to higher efficiency.
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•Controlled synthesis of ceria nanorods and nanocubes with different dimensions.•The oxidation catalytic activity of nanostructured ceria increases as the surface oxygen defects ...concentration increase.•The ceria oxidation activity is not directly related to the concentration of bulk defects.
This paper reveals the key importance of surface oxygen defects in the oxidation catalytic activity of nanostructured ceria. A series of nanostructured rods and cubes with different physico–chemical properties have been synthesized, characterized and tested in the total toluene oxidation. The variation of the temperature and base concentration during the hydrothermal syntheses of nanostructured ceria leads not only to different ceria morphologies with high shape purity, but also to structures with tuneable surface areas and defect concentrations. Ceria nanorods present a higher surface area and a higher concentration of bulk and surface defects than nanocubes associated with their exposed crystal planes, leading to high oxidation activities. However, for a given morphology, the catalytic activity for toluene oxidation is directly related to the concentration of surface oxygen defects and not the overall concentration of oxygen vacancies as previously believed.
Research on photocatalytic materials has been a field in continuous expansion in the recent decades, as it is evidenced by the large number of articles published every year. So far, more than 190 ...different semiconductors have been assayed as suitable photocatalysts. To this figure, it is necessary to add the combinations with other functional materials or between different semiconductors, as well as their morphological modifications. Summing up the outcome of these different preparation strategies eventually leads to the enormous number of photocatalytic systems that have been reported in the scientific literature. Dealing with such an amount of information requires updated and educated guidance to select the most significant realizations, and it also calls for critical assessments on how the expectations are being fulfilled. This perspective article intends to assess the state of the art of photocatalysis with regard to materials and systems, considering the well-established results, but also the emerging aspects, and the envisaged new directions of this technology in the near future. In the first part, the most relevant achievements in this area, some of them already in the market while others still in development, will be reviewed according to the current understanding. The second part of the article is devoted to the most innovative and promising photocatalysts and related systems described in the open literature.
Organic photovoltaic (OPV) technology has been developed and improved from a fancy concept with less than 1% power conversion efficiency (PCE) to over 10% PCE, particularly through the efforts in the ...last decade. The significant progress is the result of multidisciplinary research ranging from chemistry, material science, physics, and engineering. These efforts include the design and synthesis of novel compounds, understanding and controlling the film morphology, elucidating the device mechanisms, developing new device architectures, and improving large‐scale manufacture. All of these achievements catalyzed the rapid growth of the OPV technology. This review article takes a retrospective look at the research and development of OPV, and focuses on recent advances of solution‐processed materials and devices during the last decade, particular the polymer version of the materials and devices. The work in this field is exciting and OPV technology is a promising candidate for future thin film solar cells.
In this review article, we take a retrospective look at the research and development in organic photovoltaics (OPVs), and focus on recent advances of solution‐processed materials and devices during the last decade, in particular the polymer version of the materials and devices. The work in this field is exciting and OPV technology is a promising candidate for future thin film solar cells.
Visible-light-responsive photocatalysts can directly harvest energy from solar light, offering a desirable way to solve energy and environment issues. Here, we show that one-dimensional ...poly(diphenylbutadiyne) nanostructures synthesized by photopolymerization using a soft templating approach have high photocatalytic activity under visible light without the assistance of sacrificial reagents or precious metal co-catalysts. These polymer nanostructures are very stable even after repeated cycling. Transmission electron microscopy and nanoscale infrared characterizations reveal that the morphology and structure of the polymer nanostructures remain unchanged after many photocatalytic cycles. These stable and cheap polymer nanofibres are easy to process and can be reused without appreciable loss of activity. Our findings may help the development of semiconducting-based polymers for applications in self-cleaning surfaces, hydrogen generation and photovoltaics.
This study explores the capacity of the morphology analysis for railway wheel flat fault detection. A dynamic model of vehicle systems with 56 degrees of freedom was set up along with a wheel flat ...model to calculate the dynamic responses of axle box. The vehicle axle box vibration signal is complicated because it not only contains the information of wheel defect, but also includes track condition information. Thus, how to extract the influential features of wheels from strong background noise effectively is a typical key issue for railway wheel fault detection. In this paper, an algorithm for adaptive multiscale morphological filtering (AMMF) was proposed, and its effect was evaluated by a simulated signal. And then this algorithm was employed to study the axle box vibration caused by wheel flats, as well as the influence of track irregularity and vehicle running speed on diagnosis results. Finally, the effectiveness of the proposed method was verified by bench testing. Research results demonstrate that the AMMF extracts the influential characteristic of axle box vibration signals effectively and can diagnose wheel flat faults in real time.
•An adaptive multiscale morphological filter (AMMF) is proposed.•The impacts of speed and track for wheel flat fault detection are investigated.•AMMF is applied to detect the wheel fault using simulation and lab test signals.
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