Nuclear wastewater decontamination by 3D-Printed hierarchical zeolite monoliths

3D-printed monoliths of zeolites chabazite and 4A were made, characterized, and shown effective for removing strontium and caesium from water

Skin-touch-actuated textile-based triboelectric nanogenerator with black phosphorous for durable biomechanical energy harvesting

Textiles that are capable of harvesting biomechanical energy via triboelectric effects are of interest for self-powered wearable electronics. Fabrication of conformable and durable textiles with high triboelectric outputs remains challenging. Here we propose a washable skin-touch-actuated textile-based triboelectric nanogenerator for harvesting mechanical energy from both voluntary and involuntary body motions. Black phosphorus encapsulated with hydrophobic cellulose oleoyl ester nanoparticles serves as a synergetic electron-trapping coating, rendering a textile nanogenerator with long-term reliability and high triboelectricity regardless of various extreme deformations, severe washing, and extended environmental exposure. Considerably high output (~250–880 V, ~0.48–1.1 µA cm−2) can be attained upon touching by hand with a small force (~5 N) and low frequency (~4 Hz), which can power light-emitting diodes and a digital watch. This conformable all-textile-nanogenerator is incorporable onto cloths/skin to capture the low output of 60 V from subtle involuntary friction with skin, well suited for users’ motion or daily operations

Ferroelastic-switching-driven colossal shear strain and piezoelectricity in a hybrid ferroelectric

Materials that can produce large controllable strains are widely used in shape memory devices, actuators and sensors. Great efforts have been made to improve the strain outputs of various material systems. Among them, ferroelastic transitions underpin giant reversible strains in electrically-driven ferro/piezoelectrics and thermally- or magneticallydriven shape memory alloys. However, large-strain ferroelastic switching in conventional ferroelectrics is very challenging while magnetic and thermal controls are not desirable for applications. Here, we demonstrate an unprecedentedly large shear strain up to 21.5 % in a hybrid ferroelectric, C6H5N(CH3)3CdCl3. The strain response is about two orders of magnitude higher than those of top-performing conventional ferroelectric polymers and oxides. It is achieved via inorganic bond switching and facilitated by the structural confinement of the large organic moieties, which prevents the undesired 180-degree polarization switching. Furthermore, Br substitution can effectively soften the bonds and result in giant shear piezoelectric coefficient (d35 ~ 4800 pm/V) in Br-rich end of the solid solution, C6H5N(CH3)3CdBr3xCl3(1-x). The superior electromechanical properties of the compounds promise their potential in lightweight and high energy density devices, and the strategy described here should inspire the development of next-generation piezoelectrics and electroactive materials based on hybrid ferroelectrics.Comment: 32 pages, 14 figures, 5 table

Towards control of the size, composition and surface area of NiO nanostructures by Sn doping

Achieving nanostructures with high surface area is one of the most challenging tasks as this metric usually plays a key role in technological applications, such as energy storage, gas sensing or photocatalysis, fields in which NiO is gaining increasing attention recently. Furthermore, the advent of modern NiO-based devices can take advantage of a deeper knowledge of the doping process in NiO, and the fabrication of p-n heterojunctions. By controlling experimental conditions such as dopant concentration, reaction time, temperature or pH, NiO morphology and doping mechanisms can be modulated. In this work, undoped and Sn doped nanoparticles and NiO/SnO_2 nanostructures with high surface areas were obtained as a result of Sn incorporation. We demonstrate that Sn incorporation leads to the formation of nanosticks morphology, not previously observed for undoped NiO, promoting p-n heterostructures. Consequently, a surface area value around 340 m^2/g was obtained for NiO nanoparticles with 4.7 at.% of Sn, which is nearly nine times higher than that of undoped NiO. The presence of Sn with different oxidation states and variable Ni^(3+)/Ni^(2+) ratio as a function of the Sn content were also verified by XPS, suggesting a combination of two charge compensation mechanisms (electronic and ionic) for the substitution of Ni^(2+) by Sn^(4+). These results make Sn doped NiO nanostructures a potential candidate for a high number of technological applications, in which implementations can be achieved in the form of NiO-SnO_2 p-n heterostructures

Roadmap on energy harvesting materials

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere

Rare earth materials for nanoelectronic applications

This report details the workdone on using rare earth materials for nanoelectronics applications. The aspects covered include formation of rare earth oxides for thin gate dielectrics, formation of rare earth based nanocrystals into rare earth oxides. The second part deals with the formation of rare earth Ni alloy nanowires and rare earth Er Silicide for device applications. This work shows the importance of rare earth materials in nanoelectronic devices and challenges the materials integration into conventional electronic materials systems.RG 111/0

Progress and Prospects in Stretchable Electroluminescent Devices

Stretchable electroluminescent (EL) devices are a new form of mechanically deformable electronics that are gaining increasing interests and believed to be one of the essential technologies for next generation lighting and display applications. Apart from the simple bending capability in flexible EL devices, the stretchable EL devices are required to withstand larger mechanical deformations and accommodate stretching strain beyond 10%. The excellent mechanical conformability in these devices enables their applications in rigorous mechanical conditions such as flexing, twisting, stretching, and folding.The stretchable EL devices can be conformably wrapped onto arbitrary curvilinear surface and respond seamlessly to the external or internal forces, leading to unprecedented applications that cannot be addressed with conventional technologies. For example, they are in demand for wide applications in biomedical-related devices or sensors and soft interactive display systems, including activating devices for photosensitive drug, imaging apparatus for internal tissues, electronic skins, interactive input and output devices, robotics, and volumetric displays. With increasingly stringent demand on the mechanical requirements, the fabrication of stretchable EL device is encountering many challenges that are difficult to resolve. In this review, recent progresses in the stretchable EL devices are covered with a focus on the approaches that are adopted to tackle materials and process challenges in stretchable EL devices and delineate the strategies in stretchable electronics. We first introduce the emission mechanisms that have been successfully demonstrated on stretchable EL devices. Limitations and advantages of the different mechanisms for stretchable EL devices are also discussed. Representative reports are reviewed based on different structural and material strategies. Unprecedented applications that have been enabled by the stretchable EL devices are reviewed. Finally, we summarize with our perspectives on the approaches for the stretchable EL devices and our proposals on the future development in these devices.NRF (Natl Research Foundation, S’pore)Published versio

Performance optimization strategies of halide perovskite-based mechanical energy harvesters

Halide perovskites, possessing unique electronic and photovoltaic properties, have been intensively investigated over the past decade. The excellent polarization, piezoelectricity, dielectricity and photoelectricity of halide perovskites provide new opportunities for the applications of mechanical energy harvesting. Although various studies have been conducted to develop halide perovskite-based triboelectric and piezoelectric nanogenerators, strategies for their electrical performance optimization are rarely mentioned. In this review, we systematically introduce the recent research progress of halide perovskite-based mechanical energy harvesters and summarize the different optimization strategies for improving both the piezoelectric and triboelectric output of the devices, bringing some inspiration to guide future material and structure design for halide perovskite-based energy devices. A summary of the current challenges and future perspectives is also presented, offering some possible directions for development in this emerging field.Ministry of Education (MOE)Nanyang Technological UniversityThis work was supported by the Ministry of Education (MOE) Singapore, AcRF Tier 1 grant no. RT15/20 and NGF-2020-09-012. F. J. acknowledges the research scholarship awarded by the Institute of Flexible Electronics Technology of Tsinghua, Zhejiang (IFET-THU), Nanyang Technological University (NTU), and Qiantang Science and Technology Innovation Center, China (QSTIC)

Flexible and printable composite ink for thermalmanagement of soft electronics

Since heat generation in electronic devices causes thermal failure, heat dissipation is of critical importance. Furthermore, deformable devices are subjected to mechanical stress, therefore, mechanically stable thermal management material should be considered. Herein, a strategy for printable, thermally conductive, and mechanically stable composite ink for thermal management is introduced. Based on the galvanic replacement between eutectic gallium indium (EGaIn) nanoparticles and silver (Ag) flakes, decoration of the EGaIn nanoparticles on Ag flakes is resulted from the difference in standard reduction potential between Ag, Ga, and In. The resultant alloy formation(Ag–Ga or Ag–In) serves as the thermal transport junction between Ag flakes, leading to high thermal and electrical conductivity (≈140 W mK−1 and ≈106 S m−1, respectively). In addition, owing to the polymer binder, the printed ink is mechanically stable on a substrate exhibiting stable thermal conductivity and sheet resistance under the cyclic bending test. Notably, the heat dissipation of the light-emitting diode (LED) showed better performance when applied with the developed composite ink compared to commercial Ag paste and thermal paste. The junction temperature of the LED is reduced effectively, resulting in a longer lifetime of the LED. The thermal management solution can be utilized in next-generation soft electronics.National Research Foundation (NRF)This research was supported by the National Research Foundation Singapore (NRF), under its Medium Sized Center: Singapore Hybrid-Integrated Next-Generation μ-Electronics (SHINE) Centerr.

Crystallographic alignment of ZnO nanorod arrays on Zn2GeO4 nanocrystals : promising lattice-matched substrates

We demonstrated that ternary Zn2GeO4 crystals could be used as potential lattice-matched substrates for ZnO nanorod array growth. Single-crystalline Zn2GeO4 nanowires were used as substrates for crystallographic alignment of ZnO nanorod arrays. Structural characterization verified the heteroepitaxial growth between the ZnO c-plane and Zn2GeO4 side facets, which was attributed to the small lattice mismatches. The semiconducting Zn2GeO4 crystals are of potential interest as novel alternative substrates for ZnO nanorod array growth