Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

Climate change 2014 - Mitigation of climate change

Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers...

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

The triboelectric effect is ubiquitous in our everyday life and results from two different materials coming into contact. It is generally regarded as a negative effect in industry given that the electrostatic charges induced from it can lead to ignition, dust explosions, dielectric breakdown, electronic damage, etc. From an energy point of view, those electrostatic charges constitute a capacitive energy device when the two triboelectric surfaces are separated, which led to the invention of early electrostatic generators such as the “friction machine” and Van de Graaff generator.[1] As the world is marching into the era of the internet of things (IoTs) and artificial intelligence, the most vital development for hardware is a multifunctional array of sensing systems, which forms the foundation of the fourth industrial revolution toward an intelligent world. Given the need for mobility of these multitudes of sensors, the success of the IoTs calls for distributed energy sources, which can be provided by solar, thermal, wind, and mechanical triggering/vibrations. The triboelectric nanogenerator (TENG) for mechanical energy harvesting developed by Z.L. Wang’s group is one of the best choices for this energy for the new era, since triboelectrification is a universal and ubiquitous effect with an abundant choice of materials. The development of self-powered active sensors enabled by TENGs is revolutionary compared to externally powered passive sensors, similar to the advance from wired to wireless communication. In this paper, the fundamental theory, experiments, and applications of TENGs are reviewed as a foundation of the energy for the new era with four major application fields: micro/nano power sources, self-powered sensors, large-scale blue energy, and direct high-voltage power sources. A roadmap is proposed for the research and commercialization of TENG in the next 10 years.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.201802906

Triboelectric Nanogenerator: A Foundation of the Energy for the New Era

A series of flexible nanocomposite electrodes were fabricated by facile electro-deposition of cobalt and nickel double hydroxide (DH) nanosheets on porous NiCo2O4 nanowires grown radially on carbon fiber paper (CFP) for high capacity, high energy, and power density supercapacitors. Among different stoichiometries of CoxNi1–xDH nanosheets studied, Co0.67Ni0.33 DHs/NiCo2O4/CFP hybrid nanoarchitecture showed the best cycling stability while maintaining high capacitance of ∼1.64 F/cm2 at 2 mA/cm2. This hybrid composite electrode also exhibited excellent rate capability; the areal capacitance decreased less than 33% as the current density was increased from 2 to 90 mA/cm2, offering excellent specific energy density (∼33 Wh/kg) and power density (∼41.25 kW/kg) at high cycling rates (up to150 mA/cm2).

http://www.nanoscience.gatech.edu/paper/2013/13_ACSN_06.pdf

Nickel–Cobalt Hydroxide Nanosheets Coated on NiCo2O4 Nanowires Grown on Carbon Fiber Paper for High-Performance Pseudocapacitors

Conducting nanowires are of particular interest in energy-related research on devices such as supercapacitors, batteries, water splitting electrodes and solar cells. Their direct electrode/current collector contact and highly conductive 1D structure enable conducting nanowires to provide ultrafast charge transportation. In this paper, we report the facile synthesis of nickel cobalt layered double hydroxides (LDHs) on conducting Zn2SnO4 (ZTO) and the application of this material to a supercapacitor. This study also presents the first report of an enhancement of the active faradic reaction sites (electroactive sites) resulting from the heterostructure. This novel material demonstrates outstanding electrochemical performance with a high specific capacitance of 1805 F g−1 at 0.5 A g−1, and an excellent rate performance of 1275 F g−1 can be achieved at 100 A g−1. Furthermore, an asymmetric supercapacitor was successfully fabricated using active carbon as a negative electrode. This asymmetric device exhibits a high energy density of 23.7 W h kg−1 at a power density of 284.2 W kg−1. Meanwhile, a high power density of 5817.2 W kg−1 can be achieved at an energy density of 9.7 W h kg−1. More importantly, this device exhibits long-term cycling stability, with 92.7% capacity retention after 5000 cycles.

/pdf/enhancing-electrochemical-reaction-sites-in-nickel-cobalt-nkgv0t6g33.pdf

Enhancing electrochemical reaction sites in nickel-cobalt layered double hydroxides on zinc tin oxide nanowires: a hybrid material for an asymmetric supercapacitor device.

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. Incorporation of triboelectric nanogenerators into textiles is attractive for self-powered wearable electronics. Here the authors employ black phosphorus with a hydrophobic coating in a durable, washable, and air permeable textile-based device that converts biomechanical motion into electricity.

/pdf/skin-touch-actuated-textile-based-triboelectric-1kf9x5qkpx.pdf

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

In this work, monodisperse polydopamine (PDA) spheres with tunable diameters have been synthesized through a facile and low cost method using a deionized water and alcohol mixed solvent. The PDA spheres possess surface functional groups (-OH, -NH(2)), exhibiting an extraordinary versatile active nature. It is demonstrated that the PDA spheres could serve as an active template for the convenient synthesis of various nanostructures, e.g., MnO(2) hollow spheres or PDA/Fe(3)O(4) and PDA/Ag core/shell nanostructures. No surface modification or special treatment is required for the synthesis of these nanostructures, which makes the fabrication process simple and very convenient. The novel application of PDA/Fe(3)O(4) spheres as fillers in nanocomposites for high-performance capacitors is demonstrated, indicating a promising practicality. The PDA spheres provide a new general platform not only for the facile assembly of nanostructures but also a green synthetic template for practical applications.

Polydopamine Spheres as Active Templates for Convenient Synthesis of Various Nanostructures

https://dr.ntu.edu.sg/bitstream/10356/138603/2/Core-shell%20nanofiber%20mats%20for%20tactile%20pressure%20sensor%20and%20nanogenerator%20applications.pdf

Core-shell nanofiber mats for tactile pressure sensor and nanogenerator applications

Realizing energy harvesting from water flow using triboelectric generators (TEGs) based on our daily wearable fabric or textile has practical significance. Challenges remain on methods to fabricate conformable TEGs that can be easily incorporated into waterproof textile, or directly harvest energy from water using hydrophobic textile. Herein, a wearable all-fabric-based TEG for water energy harvesting, with additional self-cleaning and antifouling properties is reported for the first time. Hydrophobic cellulose oleoyl ester nanoparticles (HCOENPs) are prepared from microcrystalline cellulose, as a low-cost and nontoxic coating material to achieve superhydrophobic coating on fabrics, including cotton, silk, flax, polyethylene terephthalate (PET), polyamide (nylon), and polyurethane. The resultant PET fabric-based water-TEG can generate an instantaneous output power density of 0.14 W m−2 at a load resistance of 100 MΩ. An all-fabric-based dual-mode TEG is further realized to harvest both the electrostatic energy and mechanical energy of water, achieving the maximum instantaneous output power density of 0.30 W m−2. The HCOENPs-coated fabric provides excellent breathability, washability, and environmentally friendly fabric-based TEGs, making it a promising wearable self-powered system.

Meng-Fang Lin

Papers

Enhancing electrochemical reaction sites in nickel-cobalt layered double hydroxides on zinc tin oxide nanowires: a hybrid material for an asymmetric supercapacitor device.

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

Polydopamine Spheres as Active Templates for Convenient Synthesis of Various Nanostructures

Core-shell nanofiber mats for tactile pressure sensor and nanogenerator applications

Wearable All-Fabric-Based Triboelectric Generator for Water Energy Harvesting