Supercapacitors can harvest electrical energy from intermittent sources and transfer it quickly, but their specific energy must be raised if they are applied to efficiently power wearable and ...flexible electronics, as well as larger equipment. However, the remaining big gap between the lab research and practical applications seriously hinders the further progress of advanced supercapacitors, especially for electrode materials. Consequently, from a commercial/usable perspective, a clear guideline from lab research to commercialization is highly desired for bringing advanced supercapacitors from basic research into reality. This review focuses on the key factors of advanced supercapacitors from lab research to commercialization and summarizes recent progress in the field of supercapacitors as well as outlines key perspectives for future research. First, the several energy storage mechanisms are illustrated for building better supercapacitors. Then, the up‐to‐date key achievements and progresses of smart methods toward high‐energy supercapacitors and effective strategies for commercial‐level mass‐loading as well as high packing density electrodes are summarized and commented upon. Also, integrated systems of supercapacitors and application fields of commercial supercapacitors are also highlighted. Subsequently, future research directions are presented here to guide research toward the commercialization of advanced supercapacitors.
The remaining big gap between the lab research and practical applications seriously hinders the further progress of advanced supercapacitors, especially for electrode materials. This review focuses on providing readers a clear guideline and comprehensive insights for bringing advanced supercapacitors from basic research into reality. Moreover, several key scientific challenges and the perspectives about the commercialization of advanced supercapacitors are also discussed.
Photocatalytic nitrogen (N2) fixation suffers from low efficiency due to the difficult activation of the strongly nonpolar NN bond. In this study, a Ru–Co bimetal center is constructed at the ...interface of Ru/CoSx with S‐vacancy on graphitic carbon nitride nanosheets (Ru‐Vs‐CoS/CN). Upon adsorption, the two N atoms in N2 are bridged to the Ru–Co center, and the asymmetrical electron donation from Ru and Co atoms to N2 adsorbate highly polarized NN bond to double bond order. The plasmonic electric‐field‐enhancement effect enables the Ru/CoSx interface to boost the generation of energetic electrons. The Schottky barrier between Ru and CoSx endows the interface with electron transfer from CoSx to Ru. The Ru‐end bound N at the Ru–Co center is preferentially hydrogenated. As a result, the Ru‐Vs‐CoS/CN photocatalyst shows an NH3 production rate of up to 0.438 mmol g−1 h−1, reaching a high apparent quantum efficiency of 1.28% at 400 nm and solar‐to‐ammonia efficiency of 0.042% in pure water under AM1.5G light irradiation.
The two N atoms in N2 are bridged to the Ru–Co center on graphitic carbon nitride nanosheets. The NN bond is highly polarized to the double bond order. Energetic electrons and asymmetrical electron donation for N2 activation results in a very high NH3 production rate under full spectrum irradiation, showing a high apparent quantum yield in pure water.
Excessive accumulation of nitrate in the environment will affect human health. To combat nitrate pollution, chemical, biological, and physical technologies have been developed recently. The ...researcher favors electrocatalytic reduction nitrate reaction (NO
RR) because of the low post-treatment cost and simple treatment conditions. Single-atom catalysts (SACs) offer great activity, exceptional selectivity, and enhanced stability in the field of NO
RR because of their high atomic usage and distinctive structural characteristics. Recently, efficient transition metal-based SACs (TM-SACs) have emerged as promising candidates for NO
RR. However, the real active sites of TM-SACs applied to NO
RR and the key factors controlling catalytic performance in the reaction process remain ambiguous. Further understanding of the catalytic mechanism of TM-SACs applied to NO
RR is of practical significance for exploring the design of stable and efficient SACs. In this review, from experimental and theoretical studies, the reaction mechanism, rate-determining steps, and essential variables affecting activity and selectivity are examined. The performance of SACs in terms of NO
RR, characterization, and synthesis is then discussed. In order to promote and comprehend NO
RR on TM-SACs, the design of TM-SACs is finally highlighted, together with the current problems, their remedies, and the way forward.
The sparse 3-D phase unwrapping (PU) is a significant problem in the time-series interferometric synthetic aperture radar (TSInSAR), which is a popular technique on the extraction of the ground ...deformation. The popular 1-D + 2-D strategies in 3-D PU provide an initial temporal estimation of the phase gradients followed by a spatial integration procedure. However, the temporal PU (TPU) solution is prone to be spatially inconsistent, which increases the difficulty of the subsequent spatial PU (SPU). To solve the problem, in this article, an improved global TPU formulation targeting at a totally irrotational phase-gradient field is first proposed, which, however, has a heavy computation complexity, because numerous variables have to be optimized simultaneously. Consequently, a more feasible and practical triangle-oriented TPU (TOTPU) strategy is subsequently suggested, in which a triangle rather than an arc is the elementary unwrapping unit with the spatial irrotational constraints imposed. Furthermore, a residue-minimization algorithm is proposed to settle the problem of the "conflict edges" introduced by TOTPU, which occurs in just a small portion of arcs. Finally, the improved TPU phase gradients are integrated using an L 1 -norm SPU method with a novel weight function to obtain more reliable unwrapped phases. The proposed triangle-oriented spatial-temporal (TOST) algorithm is validated to be effective and reliable with both the simulated data and the real TerraSAR-X images. Moreover, it can be transplanted into a parallel platform for large-scale applications.
Challenges in rational designing dual‐atom catalysts (DACs) give a strong motivation to construct coordination‐activity correlations. Here, thorough coordination‐activity correlations of DACs based ...on how the changes in coordination shells (CSs) of dual‐atom Cu,Co centers influence their electrocatalytic activity in oxygen reduction reaction(ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is constructed. First, Cu,Co DACs with different CSs modifications are fabricated by using a controlled “precursors‐preselection” approach. Three DACs with unique coordination environments are characterized as secondary S atoms that directly bond to Cu,Co‐N6 in lower CSs, indirectly bond in neighboring CSs, and are doped in higher CSs, respectively. Then, experimentally and theoretically, a coordination correlation resembling a planet‐satellite system, where satellite coordinated atoms (heteroatom N, S) surround Cu‐Co dual‐atom entity in various orbitals CSs. By evaluating electrocatalytic activity indicators, differences are identified in electronic structure and electrocatalytic performance of Cu and Co centers in ORR, OER, and HER. Interestingly, initial CSs modifications for DACs may not always be advantageous for electrocatalysis. This work offers valuable insight for designing DACs for diverse applications.
Series of Cu,Co dual‐atom catalysts (DACs) with different coordination environment are controllable synthesized, where secondary S atoms are incorporated in different coordination shells (CSs) of Cu,Co centers. It is found that CSs engineering directly result in electronic redistribution of Cu,Co centers, thus regulating the electrocatalytic performance in ORR/OER/HER. This work offers a guidance for the rational design of targeted DACs.
Photocatalytic merging H2 evolution with benzyl‐alcohol (BA) oxidation offers a promising approach to producing H2 and value‐added chemicals due to water photocatalysis with a sluggish kinetic ...process and gas‐mixed H2/O2 gas security concern. Herein, incorporating electron‐deficient pyromellitic dianhydride into large π‐conjugate polymeric carbon nitride builds an effective in‐electric field (IEF). The resultant photocatalyst shows the dependence on the ratio of H2O and BA for H2 and benzaldehyde production, particularly the highest yield rate of H2 (13.87) and benzaldehyde (7.71 mmol h−1 g−1), 69.2% at 400 nm of internal quantum efficiency for H2‐evolution, and 2.15% of solar‐to‐hydrogen efficiency under simulated AM 1.5G irradiation. Mechanism analysis suggests that the strong driving force of effective IEF originates from the cooperating large delocalized π‐conjugate and electron‐deficient effect, which overwhelms the intrinsic binding energy of charge carrier to enhance its separation and migration efficiency dramatically. Moreover, extended light response and mesoporous channel in photocatalyst improve the absorption edge and tail, the n→π* transition, and mass transport of BA. In situ characterizations revealed that the enhanced H2 production is due to the releasing protons from BA oxidation via carbon‐centered radical‐mediated. These findings provide a novel strategy and deep understanding of photocatalytic coupling H2 with added‐value chemical production.
Building change detection using remote sensing images is essential for various applications such as urban management and marketing planning. However, most change detection approaches can only detect ...the intensity or type of change. The aim of this study is to dig for more change information from time-series synthetic aperture radar (SAR) images, such as the change frequency and the change moments. This paper proposes a novel multitemporal building change detection framework that can generate change frequency map (CFM) and change moment maps (CMMs) from multitemporal SAR images. We first give definitions of CFM and CMMs. Then we generate change feature using four proposed generators. After that, a new cosegmentation method combining raw images and change feature is proposed to divide time-series images into changed and unchanged areas separately. Secondly, the proposed cosegmentation and the morphological building index (MBI) are combined to extract changed building objects. Then, the logical conjunction between the cosegmentation results and the binarized MBI is performed to recognize every moment of change. In the post-processing step, we use fragment removal to increase accuracy. Finally, we propose a novel accuracy assessment index for CFM. We call this index average change difference (ACD). Compared to the traditional multitemporal change detection methods, our method outperforms other approaches in terms of both qualitative results and quantitative indices of ACD using two TerraSAR-X datasets. The experiments show that the proposed method is effective in generating CFM and CMMs.
To improve the suppression effect for the speckle noise of synthetic aperture radar (SAR) images and the ability of spatiotemporal information preservation of the filtered image without losing the ...spatial resolution, a novel multitemporal filtering method based on hypothesis testing is proposed in this paper. A framework of a two-step similarity measure strategy is adopted to further enhance the filtering results. Firstly, bi-date analysis using a two-sample Kolmogorov-Smirnov (KS) test is conducted in step 1 to extract homogeneous patches for 3-D patch stacks generation. Subsequently, the similarity between patch stacks is compared by a sliding time-series likelihood ratio (STSLR) test algorithm in step 2, which utilizes the multi-dimensional data structure of the stacks to improve the accuracy of unchanged pixels detection. Finally, the filtered values are obtained by averaging the similar pixels in time-series. The experimental results and analysis of two multitemporal datasets acquired by TerraSAR-X show that the proposed method outperforms the other typical methods with regard to the overall filtering effect, especially in terms of the consistency between the filtered images and the original ones. Furthermore, the performance of the proposed method is also discussed by analyzing the results from step 1 and step 2.
The existing unsupervised multitemporal change detection approaches for synthetic aperture radar (SAR) images based on the pixel level usually suffer from the serious influence of speckle noise, and ...the classification accuracy of temporal change patterns is liable to be affected by the generation method of similarity matrices and the pre-specified cluster number. To address these issues, a novel time-series change detection method with high efficiency is proposed in this paper. Firstly, spatial feature extraction using local statistical information on patches is conducted to reduce the noise and for subsequent temporal grouping. Secondly, a density-based clustering method is adopted to categorize the pixel series in the temporal dimension, in view of its efficiency and robustness. Change detection and classification results are then obtained by a fast differential strategy in the final step. The experimental results and analysis of synthetic and realistic time-series SAR images acquired by TerraSAR-X in urban areas demonstrate the effectiveness of the proposed method, which outperforms other approaches in terms of both qualitative results and quantitative indices of macro F1-scores and micro F1-scores. Furthermore, we make the case that more temporal change information for buildings can be obtained, which includes when the first and last detected change occurred and the frequency of changes.
There is limited evidence linking the impacts of reduced air pollution on hospital admissions. The potential biological mechanisms are still not completely understood. This study examined the effects ...of mitigated ambient pollution on hospital admissions and inflammatory biomarker levels in chronic obstructive pulmonary disease (COPD) COPD patients. Daily hospital admissions were compared over 51 days associated with the Asian Games period (Nov 1-Dec 21, 2010) with the identical calendar dates of baseline years (2004-2009 and 2011-2013). A three-year cohort study was conducted with 36 COPD patient participants. The daily particulate matter (PM10) decreased from 65.86 μg/m3 during the baseline period to 62.63 μg/m3 during the Asian Games period; the daily NO2 level decreased from 51.33 μg/m3 to 42.63 μg/m3. Between the baseline period and the Asian Games, daily hospital admissions from non-accidental diseases decreased from 116 to 93, respectively; respiratory diseases decreased from 20 to 17, respectively; and cardiovascular diseases decreased from 11 to 9 during the Asian Games period, respectively. No statistically significant reductions were seen in the remaining months of 2010 in Guangzhou, during the the Asian Games period in the control city, and two other control diseases. Furthermore, we identified significant improvement in CRP and fibrinogen by -20.4% and -15.4% from a pre-Asian game period to a during-Asian game period, respectively. For CRP, we found significant increases in NO2 at lag1-3 days after-Asian game period and significant increases in PM10 at lag1-2 days. Similar effects were also seen with fibrinogen. This discovery provides support for efforts to diminish air pollution and improve public health through human air pollutants intervention. Improved air pollution during the 2010 Asian games was correlated with decreases in biomarkers associated with systemic inflammation in COPD patient participants.
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