A facile fast laser nanoscale welding process uses the plasmonic effect at a nanowire (NW) junction to suppress oxidation and successfully fabricate a Cu‐NW‐based percolation‐network conductor. The ...“nanowelding” process does not require an inert or vacuum environment. Due to the low‐temperature and fast‐process nature, plasmonic laser nanowelding may form Cu‐nanowire networks on heat‐sensitive, flexible or even stretchable substrates.
Laser induced selective photothermochemical reduction is demonstrated to locally and reversibly control the oxidation state of Cu and Cu oxide nanowires in ambient conditions without any inert gas ...environment. This new concept of “nanorecycling” can monolithically integrate Cu and Cu oxide nanowires by restoring oxidized Cu, considered unusable for the electrode, back to a metallic state for repetitive reuse.
•We discover interesting tweets for a wide audience based on topic identification.•We model Trend Sensitive-LDA that reflects the current and popular trends.•We weight topics by exploiting their ...representative words.•We weight topics by analyzing spatial and temporal variation of their probabilities.•The most interesting tweets contain latent topics that are assigned a high weight.
Social media platforms such as Twitter are becoming increasingly mainstream which provides valuable user-generated information by publishing and sharing contents. Identifying interesting and useful contents from large text-streams is a crucial issue in social media because many users struggle with information overload. Retweeting as a forwarding function plays an important role in information propagation where the retweet counts simply reflect a tweet’s popularity. However, the main reason for retweets may be limited to personal interests and satisfactions. In this paper, we use a topic identification as a proxy to understand a large number of tweets and to score the interestingness of an individual tweet based on its latent topics. Our assumption is that fascinating topics generate contents that may be of potential interest to a wide audience. We propose a novel topic model called Trend Sensitive-Latent Dirichlet Allocation (TS-LDA) that can efficiently extract latent topics from contents by modeling temporal trends on Twitter over time. The experimental results on real world data from Twitter demonstrate that our proposed method outperforms several other baseline methods.
The fast development of nanoscience and nanotechnology has significantly advanced the fabrication of nanocatalysts and the in‐depth study of the structural‐activity characteristics of materials at ...the atomic level. Vacancies, as typical atomic defects or imperfections that widely exist in solid materials, are demonstrated to effectively modulate the physicochemical, electronic, and catalytic properties of nanomaterials, which is a key concept and hot research topic in nanochemistry and nanocatalysis. The recent experimental and theoretical progresses achieved in the preparation and application of vacancy‐rich nanocatalysts for electrochemical water splitting are explored. Engineering of vacancies has shown to open up a new avenue beyond the traditional morphology, size, and composition modifications for the development of nonprecious electrocatalysts toward efficient energy conversion. First, an introduction followed by discussions of different types of vacancies, the approaches to create vacancies, and the advanced techniques widely used to characterize these vacancies are presented. Importantly, the correlations between the vacancies and activities of the vacancy‐rich electrocatalysts via tuning the electronic states, active sites, and kinetic energy barriers are reviewed. Finally, perspectives on the existing challenges along with some opportunities for the further development of vacancy‐rich noble metal‐free electrocatalysts with high performance are discussed.
Recent experimental and theoretical achievements in vacancy‐rich transition‐metal‐based electrocatalysis for water splitting are reviewed, which include the vacancy types, synthetic approaches, and advanced techniques to characterize the vacancies. Importantly, the functions of vacancies in tuning the electronic states, active sites, and kinetic energy barriers of electrocatalysts are summarized. Finally, some perspectives of the future research in vacancy‐rich electrocatalysis are discussed.
Flexo-photovoltaic effect Yang, Ming-Min; Kim, Dong Jik; Alexe, Marin
Science (American Association for the Advancement of Science),
05/2018, Volume:
360, Issue:
6391
Journal Article
Peer reviewed
Open access
It is highly desirable to discover photovoltaic mechanisms that enable enhanced efficiency of solar cells. Here we report that the bulk photovoltaic effect, which is free from the thermodynamic ...Shockley-Queisser limit but usually manifested only in noncentrosymmetric (piezoelectric or ferroelectric) materials, can be realized in any semiconductor, including silicon, by mediation of flexoelectric effect. We used either an atomic force microscope or a micrometer-scale indentation system to introduce strain gradients, thus creating very large photovoltaic currents from centrosymmetric single crystals of strontium titanate, titanium dioxide, and silicon. This strain gradient-induced bulk photovoltaic effect, which we call the flexo-photovoltaic effect, functions in the absence of a p-n junction. This finding may extend present solar cell technologies by boosting the solar energy conversion efficiency from a wide pool of established semiconductors.
Manipulation of ferroic order parameters, namely (anti‐)ferromagnetic, ferroelectric, and ferroelastic, by light at room temperature is a fascinating topic in modern solid‐state physics due to ...potential cross‐fertilization in research fields that are largely decoupled. Here, full optical control, that is, reversible switching, of the ferroelectric/ferroelastic domains in BiFeO3 thin films at room temperature by the mediation of the tip‐enhanced photovoltaic effect is demonstrated. The enhanced short‐circuit photocurrent density at the tip contact area generates a local electric field well exceeding the coercive field, enabling ferroelectric polarization switching. Interestingly, by tailoring the photocurrent direction, via either tuning the illumination geometry or simply rotating the light polarization, full control of the ferroelectric polarization is achieved. The finding offers a new insight into the interactions between light and ferroic orders, enabling fully optical control of all the ferroic orders at room temperature and providing guidance to design novel optoferroic devices for data storage and sensing.
Full optical control of ferroelectric order parameters at room temperature is demonstrated by a combination of the bulk photovoltaic effect and the tip of an atomic force microscope. The ferroelectric polarization of a BiFeO3 thin film can be reversibly switched solely by light via changing illumination areas or simply rotating the light polarization angles.
Utilization of diffusive solar energy through photocatalytic processes for environmental purification and fuel production has long been pursued. However, efficient capture of visible–near‐infrared ...(NIR) photons, especially for those with wavelengths longer than 600 nm, is a demanding quest in photocatalysis owing to their relatively low energy. In recent years, benefiting from the advances in photoactive material design, photocatalytic reaction system optimization, and new emerging mechanisms for long‐wavelength photon activation, increasing numbers of studies on the harnessing of visible–NIR light for solar‐to‐chemical energy conversion have been reported. Here, the aim is to comprehensively summarize the progress in this area. The main strategies of the long‐wavelength visible–NIR photon capture and the explicitly engineered material systems, i.e., narrow optical gap, photosensitizers, upconversion, and photothermal materials, are elaborated. In addition, the advances in long‐wavelength light‐driven photo‐ and photothermal‐catalytic environmental remediation and fuel production are discussed. It is anticipated that this review presents the forefront achievements in visible–NIR photon capture and at the same time promotes the development of novel visible–NIR photon harnessing catalysts toward efficient solar energy utilization.
Recent progress in visible–NIR photon capture is reviewed. Distinct strategies and explicitly engineered material systems to harvest visible–NIR light, and the advances in visible–NIR‐driven photo‐ and photothermal‐catalytic environmental remediation and fuel production are presented. Moreover, perspectives on the challenges along with opportunities for further development of visible–NIR solar photon conversion through photo and photothermal processes are discussed.
The wide spectral range of the solar flux with undesirable diffused energy distribution remains a substantial impediment to the high‐efficiency utilization of the whole spectrum. Here, inspired by ...the spectrally selective sunlight utilization of plants, a spectrum‐tailored solar harnessing aerogel is conceived. It is composed of oxygen vacancy (Ov) defect‐rich semiconductor HNb3O8 (D‐HNb3O8) nanosheets and polyacrylamide (PAM) framework to perform all‐in‐one photochemical and photothermal full solar energy conversion. The aerogel selectively utilizes the whole solar spectrum, in which high energy ultraviolet (UV) photon is converted into high redox potential electron–hole pairs, while low energy visible‐near infrared (NIR) photons are transformed into heat. The designed solar absorber‐polymer composite shows energy harnessing‐conversion capability with desired heat insulation, reactant enrichment, rapid mass diffusion and capillary pumping characteristics, thus realizing a high efficient steam generation and photochemical activity. This cooperative photochemical and photothermal solar energy conversion, at respective optimal working spectrum, holds great promise for optimizing and maximizing the solar energy utilization, as well as opening up opportunities to explore simultaneous multifunctional usage of solar energy.
A spectrum‐tailored solar harnessing aerogel is conceived. It selectively utilizes the whole solar spectrum, in which high energy ultraviolet photons are converted into high redox potential electron–hole pairs to drive photochemical conversion, while low energy visible‐near infrared photons are transformed into heat to drive photothermal evaporation, thereby optimally utilizing the full solar spectrum with high conversion efficiency.
Steel has versatile application in chemical, structure and construction industries owing to its mechanical properties. However, it is susceptible to corrosion in acid environments. Thus, it requires ...to protect the steel from corrosion. Different types of corrosion resistance steel, coatings and inhibitors are developed to mitigate the corrosion, but, inhibitor is the best remedies to control the corrosion of steel in acid condition. Moreover, organic and green inhibitors used in acid condition for descaling, acid pickling, pipelines, boiler tubes and oil-wells. Organic inhibitors reduce the dissolution of steel in acid but, it is hazardous, expensive and needs expertise to synthesize the inhibitor. Therefore, there is utmost required to study and compile the latest research about the eco-friendly corrosion inhibitors, which showed more than 90% corrosion inhibition efficiency. In the present study, I have reviewed the state-of-arts, and compile the latest development in organic and eco-friendly corrosion inhibitor used in acid environment as well as suggested about the future scope and role of green inhibitor for sustainable society, which is economical, less hazardous and readily available from the natural sources.
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