Inorganic/Organic hybrid superlattice films toward next-generation flexible/wearable thermoelectric devices

Liquid exfoliation has proven to be a scalable and versatile technique to produce large-scale two-dimensional (2D) nanosheets among graphene, boron nitrides, layered perovskites and transition metal dichalcogenides. This also provides new insights into the assembly of multilayer heterostructures for novel functionalities. Here we present a solution-processed method to fabricate 2D inorganic/organic superlattice film for thermal energy harvesting, which can be either free-standing or be deposited onto substrates. The organic layer provides charge carriers to the inorganic layer, suppresses the overall thermal conductivity, and allows the material to be flexible. We have fabricated a thermoelectric module, which can generate a high power density of 2.5 W/m2 at a temperature gradient of 70K, hitting new record among the organic-based flexible thermoelectric devices. Flexibility of our newly developed superlattice materials combined with organic TE materials would enable us to design various types of TE modules that cannot be realized by using conventional hard and stiff inorganic materials. Our newly designed TE modules will be demonstrated to be useful for energy harvesting in the future IoT society. Please click Additional Files below to see the full abstract

Self-assembly of a rare high spin FeII/PdII tetradecanuclear cubic cage constructed via the metalloligand approach

Polynuclear heterobimetallic coordination cages in which different metal cations are con-nected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanu-clear heterobimetallic [Fe8 Pd6 L8 ](BF4 ]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3 OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of the eight corners of the discrete cubic structure

Anomalous structural evolution and glassy lattice in mixed-halide hybrid perovskites

Hybrid halide perovskites have emerged as highly promising photovoltaic materials because of their exceptional optoelectronic properties, which are often optimized via compositional engineering like mixing halides. It is well established that hybrid perovskites undergo a series of structural phase transitions as temperature varies. In this work, the authors find that phase transitions are substantially suppressed in mixed-halide hybrid perovskite single crystals of MAPbI3-xBrx (MA = CH3NH3+ and x = 1 or 2) using a complementary suite of diffraction and spectroscopic techniques. Furthermore, as a general behavior, multiple crystallographic phases coexist in mixed-halide perovskites over a wide temperature range, and a slightly distorted monoclinic phase, hitherto unreported for hybrid perovskites, is dominant at temperatures above 100 K. The anomalous structural evolution is correlated with the glassy behavior of organic cations and optical phonons in mixed-halide perovskites. This work demonstrates the complex interplay between composition engineering and lattice dynamics in hybrid perovskites, shedding new light on their unique properties.Peer ReviewedPostprint (published version

Body Heat Powers Future Electronic Skins

© 2019 Elsevier Inc. Ruoming Tian recently joined the Mark Wainwright Analytical Centre as an XRD research assistant at the University of New South Wales. She was formerly a Research Scientist at the Toyota Physical and Chemical Research Institute in Japan (2015–2018) and received her PhD from the University of New South Wales in 2014. Her research interests focus on the nano- and micro-materials, flexible hybrid materials, and smart devices for harvesting both high- and low-grade thermal energy. She has published 2 book chapters and 18 peer-reviewed articles and delivered more than 15 talks at international conferences and leading research institutes. Yuqing Liu is currently an Associate Research Fellow and received her PhD (2018) in the Intelligent Polymer Research Institute (IPRI), University of Wollongong, Australia. Her research interest is on the fabrication of wearable energy storage and conversion devices (e.g. thermos-cells, batteries, supercapacitors, etc.), mainly focusing on nanostructured electrode materials, gel electrolyte/electrode interface, and device fabrication via printing techniques. Kunihito Koumoto, Professor Emeritus of Nagoya University, received his BS, MS, and PhD from the University of Tokyo (UT). He served as an Assistant Professor, Lecturer, and Associate Professor at UT (1979–1992) and a full professor at Nagoya University (1992–2015). He has published 495 papers and reviews and 58 book chapters in inorganic materials chemistry. He was awarded Medal with Purple Ribbon by the Emperor of Japan in 2013 and Outstanding Achievement Award by the International Thermoelectric Society in 2018. His current research focuses on inorganic/organic nanohybrid thermoelectrics for energy harvesting. Koumoto can be reached by email at [email protected]. Jun Chen is currently a Full Professor at IPRI|ACES, Australian Institute for Innovative Materials, University of Wollongong (UOW). He received BE from Zhejiang University of Technology (1995) and PhD from UOW (2003). Professor Chen has published more than 180 papers and has been named a Highly Cited Researcher for 2018 (Clarivate Analytics). His research interests include sustainable energy devices, electro-/bio-interfaces, nano-/micro-materials, 2D/3D printing, and smart wearable electronic devices. Apart from academic achievements, Chen has also been involved in two spin-off companies: AQUAHYDREX as one of the key inventors, and IMAGINE as one of the scientific founders. The rising elderly population is driving the need for home health care and remote diagnosis. Emerging E-skins hold great promise to both non-invasively monitor patient vitals and provide rapid and personalized health advice. However, powering these synthetic E-skins in a reliable, convenient, and unattended manner is yet to be achieved. Here, we will present the perspective of utilizing a skin-conformal thermoelectric generator as the potential power supply. We will discuss the conceptual design of such devices, desired materials, and associated fabrication routes and also provide a direction for future research in the E-skin field

The development of high-performance calcium cobaltates for thermoelectric power regeneration

Transition metal oxide Ca3Co4O9+δ has demonstrated to be one of the most promising p-type thermoelectric materials for power regeneration. In this dissertation, the evolution of crystal structure with various dopants (i.e., Fe, Ga and Bi) was characterized by employing synchrotron powder diffraction and X-ray absorption spectroscopy. Experimental results show that both Ga and Fe were preferentially located on Co site in the rock-salt type ([Ca2CoO3]) layer rather than the hexagonal CdI2-type ([CoO2]) layer, as previously assumed in the literatures. The doped Bi atoms were found to be located on both Ca and Co site in the [Ca2CoO3] layer, with the solubility of ~5-6% on each site. It is also found that Bi substitution did not change the average Co valence states but affected the Co coordination environment in the [Ca2CoO3] layer, in which the Co ions showed more preference to reside in the tetrahedral site upon Bi doping. Based on the crystallographic information, the influence of Fe, Ga and Bi substitution on the thermoelectric properties was systematically investigated. Experimental results show that both Fe and Ga substitution decreases electrical resistivity and thermal conductivity of Ca3Co4O9+δ while less affects the Seebeck coefficient. Phonon density of states was investigated by means of inelastic neutron scattering and the results revealed that the suppressed optical phonon vibration, which was responsible for the reduced thermal conductivity with Bi doping. In addition, it is the first time to show the key role of Bi, which substantially improved electrical transport properties of this material, is to reduce the hopping energy that drives the charge carriers to transfer from the [Ca2CoO3] layer to [CoO2] layer.The highest figure of merit ZT achieved in present study is ~0.72 at 966K, for the Bi/Ga co-doped sample with ~ 40% porosity. This value is comparable to that of Ca3Co4O9+δ single crystal and is among the highest ZT values reported so far for polycrystalline oxide-based thermoelectric materials

Formation and Photocatalytic Activity of BaTiO3 Nanocubes via Hydrothermal Process

We reported a facile hydrothermal approach to synthesize BaTiO3 nanocubes with controlled sizes for degradation of methylene blue (MB). The nanocubes with reaction time of 48 hours exhibited the highest photocatalytic efficiency, owing to their narrower size distribution and better crystallinity compared to those of 24 hours and, at the meantime, smaller particle size than those of 72 hours. This work also demonstrated the degradation of methylene orange (MO) using BaTiO3 nanocubes synthesized for 48 hours. Compared with the removal of MB, BaTiO3 had lower photocatalytic activity on MO, mainly due to the poorer absorption behavior of MO on the surface of BaTiO3 nanocubes. The degradation efficiency for each photocatalytic reaction was calculated. The possible mechanism of the photocatalytic decomposition on MB has been addressed as well

Epidemiology of Klebsiella pneumoniae bloodstream infections in a teaching hospital: factors related to the carbapenem resistance and patient mortality

Abstract Background Although Klebsiella pneumoniae bloodstream infections (KP-BSIs) have recently attracted attention due to an alarming raise in morbidity and mortality, there have been few reports on the epidemiology of KP-BSIs in mainland China. We sought to describe the epidemiological, microbiological, and clinical characteristics of KP-BSIs, focusing on the risk factors of carbapenem resistance and patient mortality. Methods A retrospective analysis of WHONET data of KP-BSI patients admitted to a teaching hospital in Shanghai, China, between January 1, 2011 and December 31, 2015 was performed, and the annual percentage of patients with carbapenem-resistant K. pneumoniae (CRKP) was determined. Risk factors related to the carbapenem resistance and patient mortality were analyzed using binary logistic regression model. The genetic relatedness of CRKP strains isolated from intensive care unit (ICU) patients was determined by pulsed-field gel electrophoresis (PFGE). Results A total of 293 incidences of KP-BSIs were identified in a 5-year period, 22.18% of these (65/293) were CRKP strains, and the proportion of CRKP-BSI in ICU was 59.62% (31/52), equaling the levels observed in the epidemic regions. A number of KP-BSIs (114), obtained from January 1, 2014, to December 31, 2015, were further investigated. Skin and soft tissue infection source (odds ratio [OR] 26.63, 95% confidence interval [CI] 4.8–146.8) and ICU-acquired infection (OR 5.82, 95% CI 2.0–17.2) was shown to be powerful risk factors leading to the development of CRKP-BSI. The crude 28-day mortality rates of KP-BSI and CRKP-BSI patients were 22.8% and 33.3%, respectively. Lung as the probable source of infection (OR 4.23, 95% CI 1.0–17.3), and high Sequential Organ Failure Assessment (SOFA) score (OR 1.40, 95% CI 1.2–1.6) were strong prognostic factors determining crude 28-day KP-BSI mortality rates. PFGE analysis demonstrated that 10/11 random CRKP isolates in ICU belonged to the same clonal type. Conclusions During the study period, we observed a significant increase in the occurrence of CRKP infections among the identified KP-BSIs in our hospital and especially in ICU, and we demonstrated that carbapenem resistance is associated with the increased mortality of KP-BSI patients

Visible-light-responsive self-assembled complexes: improved photoswitching properties by metal ion coordination

A photoswitchable ligand based on azobenzene is self-assembled with palladium(II) ions to form a [Pd2(E-L)4]4+ cage. Irradiation with 470 nm light results in the near quantitative switching to a monomeric species [Pd(Z-L)2]2+. The assembled structures improve the selectivity of photoswitching towards the metastable isomer and increase its thermal lifetime