Showing papers by "Bao Yang published in 2019"

Nature-inspired salt resistant bimodal porous solar evaporator for efficient and stable water desalination

Abstract: The shortage of clean water is one of the predominant causes of human mortality, especially in remote rural areas. Currently, solar steam generation is being adopted as an efficient, sustainable, and low-cost means for water desalination to produce clean water. However, preventing salt accumulation during operation while maintaining long-term stability and a rapid evaporation rate is a critical challenge that needs to be urgently addressed to further facilitate the practical applications of solar desalination, especially for desalinating high-salinity brine. Here, we demonstrate that a bimodal porous structure (e.g., balsa wood) can serve as an efficient and stable solar vapor generator for high-salinity brine desalination. Taking advantage of the inherent bimodal porous and interconnected microstructures of balsa wood, rapid capillary transport through the microchannels and efficient transport between the micro- and macrochannels through ray cells and pits in the bimodal evaporator can lead to quick replenishment of surface vaporized brine to ensure fast and continuous clean water vapor generation. The bimodal evaporator demonstrates a rapid evaporation rate of 6.4 kg m−2 h−1 under 6 suns irradiation and outstanding long-term stability for desalination of high salinity brine. The large vessel channels play a critical role in preventing salt from accumulating, as evidenced by controlled experiments with large vessels either blocked in the bimodal evaporator (balsa evaporator) or absent in a unimodal evaporator (e.g., cedar wood) whose porous structure occurs naturally without large vessels. Both approaches demonstrate severe salt accumulation during solar desalination due to a lack of sufficient brine replenishment from the bulk solution beneath. With its unique bimodal porous and interconnected microstructure configuration obtained by a facile and scalable fabrication method, our bimodal porous structured evaporator device represents an efficient, stable, low-cost, and environmentally friendly solar vapor generator for high-salinity brine desalination.

Clear Wood toward High-Performance Building Materials.

Abstract: Developing advanced building materials with both excellent thermal insulating and optical properties to replace common glass (thermal conductivity of ∼1 W m–1 K–1) is highly desirable for energy-ef...

General, Vertical, Three-Dimensional Printing of Two-Dimensional Materials with Multiscale Alignment

Abstract: Two-dimensional (2D) materials (e.g., boron nitride (BN), graphene, and MoS2) have great potential in emerging energy, environmental, and electronics applications. Assembly of 2D materials into vertically aligned structures is highly desirable (e.g., low tortuosity for rapid ion transport in fast charging-discharging batteries, guiding thermal transport for efficient thermal management), yet extremely challenging due to the energetically unfavorable in processing. Herein, we reported a general three-dimensional (3D) printing method to fabricate vertically aligned 2D materials in multiscale, using BN nanosheet as the proof-of-concept. The 3D-printed macroscale rods are composed of vertically aligned BN nanosheets at the nanoscale. The formation of the hierarchical aligned structure is enabled by the optimized ink that holds a significant shear-thinning behavior and an ultrahigh storage modulus, as identified at a narrow region in the printability diagram. The resulting vertically aligned multiscale structure with 2D nanosheets demonstrated an outstanding through-plane thermal conductivity, up to 5.65 W m-1 K-1, significantly higher than the value of conventional BN based structures where the sheets are horizontally aligned. The vertical 3D printing of 2D BN nanosheets can be expanded to other 2D materials in constructing hierarchically aligned structures for a range of emerging technologies such as batteries, membranes, and structural materials.

Synthesis of Metal Oxide Nanoparticles by Rapid, High-Temperature 3D Microwave Heating

Abstract: Microwave-assisted fabrication has propelled the recent synthesis and processing approaches of various nanomaterials. However, in most previous studies, the synthesis temperature is limited to below 1100 K, which restricts its application. Here, a rapid, in situ 3D heating method to manufacture well-dispersed metal oxide nanoparticles on a 3D carbonized wood (denoted as C-wood) host using microwaves as the driving power is reported. The moderate electronic conductivity of C-wood contributes to the local Joule heating and the good thermal conductivity guarantees the rapid 3D heating of the overall material. The temperature of the C-wood increases from room temperature to ≈2200 K in 4 s (≈550 K s−1), stabilizing to 1400 K, and then cooling back down to room temperature within 2 s. The preloaded precursor salts rapidly decompose and form ultrafine (≈11 nm) metal oxide nanoparticles on the surface of the C-wood during the rapid quenching. The process takes place in air, which helps prevent the metal oxides from being reduced by the carbon. The 3D heating method offers an effective route to the rapid and scalable synthesis of metal oxide nanoparticles.

Designing Textile Architectures for High Energy-Efficiency Human Body Sweat- and Cooling-Management

Abstract: Thermal management of textiles requires local microclimate control over heat and wet dissipation to create a comfortable thermal-wet environment at the interface of the human body and clothing. Herein, we design a fabric capable of both sweat- and cooling-management using a knitted fabric featuring a bilayer structure consisting of hydrophobic polyethylene terephthalate and hydrophilic cellulose fibers to simultaneously achieve high infrared (IR) transmittance and good thermal-wet comfort. The IR transmission of this cooling textile increased by ~ twofold in the dry state and ~ eightfold in the wet state compared to conventional cotton fabric. When the porosity changes from 10 to 47% with the comparison of conventional cotton fabric and our cooling textile, the heat flux is increased from 74.4 to 152.3 W/cm2. The cooling effect of the cooling fabric is 105% greater than that of commercial cotton fabric, which displays a better thermal management capacity for personal cooling. This bilayer design controls fast moisture transfer from inside out and provides thermal management, demonstrating high impact not only for garments, but also for other systems requiring heat regulation, such as buildings, which could mitigate energy demand and ultimately contribute to the relief of global energy and climate issues.

Rapid, High-Temperature, In Situ Microwave Synthesis of Bulk Nanocatalysts.

Abstract: Carbon-black-supported nanoparticles (CNPs) have attracted considerable attention for their intriguing catalytic properties and promising applications. The traditional liquid synthesis of CNPs commonly involves demanding operation conditions and complex pre- or post-treatments, which are time consuming and energy inefficient. Herein, a rapid, scalable, and universal strategy is reported to synthesize highly dispersed metal nanoparticles embedded in a carbon matrix via microwave irradiation of carbon black with preloaded precursors. By optimizing the amount of carbon black, the microwave absorption is dramatically improved while the thermal dissipation is effectively controlled, leading to a rapid temperature increase in carbon black, ramping to 1270 K in just 6 s. The whole synthesis process requires no capping agents or surfactants, nor tedious pre- or post-treatments of carbon black, showing tremendous potential for mass production. As a proof of concept, the synthesis of ultrafine Ru nanoparticles (≈2.57 nm) uniformly embedded in carbon black using this microwave heating technique is demonstrated, which displays remarkable electrocatalytic performance when used as the cathode in a Li-O2 battery. This microwave heating method can be extended to the synthesis of other nanoparticles, thereby providing a general methodology for the mass production of carbon-supported catalytic nanoparticles.

Highly Sensitive and Durable Structured Fibre Sensors for Low-Pressure Measurement in Smart Skin.

Abstract: Precise measurements of low pressure are highly necessary for many applications. This study developed novel structured fibre sensors embedded in silicone, forming smart skin with high sensitivity, high durability, and good immunity to crosstalk for precise measurement of pressure below 10 kPa. The transduction principle is that an applied pressure leads to bending and stretching of silicone and optical fibre over a purposely made groove and induces the axial strain in the gratings. The fabricated sensor showed high pressure sensitivity up to 26.8 pm/kPa and experienced over 1,000,000 cycles compression without obvious variation. A theoretical model of the sensor was presented and verified to have excellent agreement with experimental results. The prototype of smart leg mannequin and wrist pulse measurements indicated that such optical sensors can precisely measure low-pressure and can easily be integrated for smart skins for mapping low pressure on three-dimensional surfaces.

Modeling analysis on solar steam generator employed in multi-effect distillation (MED) system

Abstract: Recently the porous bilayer wood solar collectors have drawn increasing attention because of their potential application in solar desalination. In this paper, a thermodynamic model has been developed to analyze the performance of the wood solar collector. A modeling analysis has also been conducted to assess the performance and operating conditions of the multiple effect desalination (MED) system integrated with the porous wood solar collector. Specifically, the effects of operating parameters, such as the motive steam temperature, seawater flow rate, input solar energy and number of effects on the energy consumption for each ton of distilled water produced have been investigated in the MED desalination system combined with the bilayer wood solar steam generator. It is found that, under a given operating condition, there exists an optimum steam generation temperature of around 145°C in the wood solar collector, so that the specific power consumption in the MED system reaches a minimum value of 24.88 kWh/t. The average temperature difference is significantly affected by the solar heating capacity. With the solar capacity increasing from 50 kW to 230 kW, the average temperature difference increases from 1.88°C to 6.27°C. This parametric simulation study will help the design of efficient bilayer wood solar steam generator as well as the MED desalination system.

Intelligent bionic human body part model detection device and manufacturing method

Abstract: The invention provides an intelligent bionic human body part model detection device and a manufacturing method. The device comprises a bionic human body part model, and a plurality of optical fiber grating sensing units integrated on an optical fiber and arranged in a plurality of preset positions of the bionic human body part model. The device disclosed by the invention can improve the accuracy of detecting the pressure applied to the intelligent bionic human body part model.

Intelligent bionic human body part model detection device and method for manufacturing same

Abstract: Disclosed are an intelligent bionic human body part model detection device and a method for manufacturing same. The device comprises: a bionic human body part model (1); and multiple optical fiber grating sensing units (5) which are integrated on an optical fibre and arranged at multiple pre-determined positions of the bionic human body part model (1). The device can improve the accuracy of the detection of pressure applied to the intelligent bionic human body part model.