Tuning the structure of borane-nitrogen derivatives towards high-performance carbon nanotubes-based n-type thermoelectric materials

Mao, Xianhua; Li, Ziyu; Liu, Yijia; Nie, Xiuxiu; Li, Benzhang; Jiang, Qinglin; Gao, Chunmei; Gao, Yuan; Wang, Lei

doi:10.1016/j.cej.2020.126616

Cited by 29 publications

(18 citation statements)

References 57 publications

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“…A hot end was heated with a heating plate, and a cool end was placed in the air. The temperatures of the hot ( T hot ) and cool ( T cold ) ends were measured with an infrared thermal imager, which has been reported previously. , The equation of temperature difference (Δ T ) is Δ T = T hot – T cold . The Δ T values could be achieved by heating the heating plate and raising the temperature of the hot end.…”

Section: Resultsmentioning

confidence: 99%

Promoting the Thermoelectric Performance of Single-Walled Carbon Nanotubes by Inserting Discotic Liquid-Crystal Molecules

Zhou

et al. 2021

ACS Sustainable Chem. Eng.

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Single-walled carbon nanotubes (SWCNTs) are desirable flexible thermoelectric materials in applications of large-scale low-grade thermal energy. However, weak Seebeck coefficients of SWCNTs around room temperature limit their development as a flexible power generator. In this work, we significantly improve the Seebeck coefficients of SWCNT-based composites by integrating the discotic liquid-crystal 2,3,6,7,10,11-hexakis(hexyloxy) triphenylene (HAT6) through the energy-filtering effect. The Seebeck coefficients of SWCNT/HAT6 composite films are about more than twice that of the pristine SWCNT films, and a maximum power factor of 408.23 ± 48.96 μW m −1 K −2 is achieved at room temperature, which is one of the highest values among organic small-moleculebased thermoelectric composites reported so far. The flexible power generator based on p-type SWCNT/HAT6 films is first assembled. An outstanding power density of 0.64 μW cm −2 with a thermoelectric voltage of 17.64 mV at a temperature gradient of 56 K is achieved. This study demonstrates that SWCNT/ discotic liquid-crystal composites show great promise in thermoelectric (TE) materials and open a new avenue for the development of TE devices.

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Section: Resultsmentioning

confidence: 99%

Promoting the Thermoelectric Performance of Single-Walled Carbon Nanotubes by Inserting Discotic Liquid-Crystal Molecules

Zhou

et al. 2021

ACS Sustainable Chem. Eng.

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“…Figure 4c depicts the temperature dependence of open-circuit voltages generated by the TE device. The theoretical voltages can be calculated according to the following formula 47 V n S S T ( )…”

Section: Resultsmentioning

confidence: 99%

“…Figure c depicts the temperature dependence of open-circuit voltages generated by the TE device. The theoretical voltages can be calculated according to the following formula where n is the number of thermocouples in the TE device and S p and S n represent absolute values of the Seebeck coefficient of the p-type and the n-type SWCNT film, respectively. As shown in Figure c, the actual open-circuit voltage generated by the TE device can reach a high value of 21.5 mV, when the temperature difference of two sides of the TE device was 76 K. The voltage–current curve and the power–current curve of the TE device are illustrated in Figure d, and the optimum value of the actual output power reaches 5.3 μW at a temperature difference of 76 K. A power density of 0.42 μW cm –2 is obtained by dividing the power output by the actual area of the TE module (12.5 cm 2 ).…”

Section: Resultsmentioning

confidence: 99%

Oxygen-Rich Polymer Polyethylene Glycol-Functionalized Single-Walled Carbon Nanotubes Toward Air-Stable n-Type Thermoelectric Materials

Wang

Yang

et al. 2021

ACS Appl. Mater. Interfaces

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It is crucial for thermoelectric (TE) devices to obtain both p-type and n-type materials and control charge carrier density. However, n-type thermoelectric materials are quite deficient and have lower thermoelectric properties. We report one oxygen-rich polymer named polyethylene glycol (PEG) for converting p-type single-walled carbon nanotubes (SWCNTs) to air-stable n-type thermoelectric materials. When pristine SWCNTs were doped with 2 mg·mL–1 PEG in an ethanol solution, the optimal Seebeck coefficient of PEG/SWCNT composites reached −50.8 μV·K–1. The result of ultraviolet photoelectron spectroscopy demonstrated that the lone pair of oxygen atoms in the PEG chain has electron transferability to SWCNTs. According to the hard and soft acid and base theory, sodium hydroxide (NaOH) was further introduced to improve air stability and thermoelectric performance of doped SWCNTs. As a result, PEG/NaOH/SWCNT composites achieved the highest power factor of 173.8 μW·m–1·K–2 at 300 K. Meanwhile, their final changes in electrical conductivity and the Seebeck coefficient are less than 8% in the investigation of air stability over two months. Inspired by this finding, we fabricated the TE generator composed of the pristine p-type SWCNTs and n-type PEG/NaOH/SWCNT composites. The maximum output power of this robust TE device reached 5.3 μW at a temperature gradient of 76 K, which is superior to many reported TE devices. Moreover, the experimental procedure is attractive as a sustainable process for materials preparation. Our study has indicated that the oxygen-rich polymer-functionalized SWCNTs have huge potential for developing air-stable n-type carbon-based thermoelectric materials.

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“…where R i is the internal resistance of the fabricated p-n device (16.3 Ω). The results show that the internal resistance of these modules is relatively low compared to those of previously reported organic thermoelectric modules [61,62]. The P AC values for ΔT = 15, 30, 45, 60, and 75 °C compare favorably with the P TH values calculated using Equation (4) (Figure S10(B)), suggesting that higher power output can be achieved by connecting more units in series.…”

Section: Resultsmentioning

confidence: 50%

Green Route for Fabrication of Water-Treatable Thermoelectric Generators

et al. 2022

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Since future energy harvesting technologies require stable supply and high-efficiency energy conversion, there is an increasing demand for high-performance organic thermoelectric generators (TEGs) based on waterproof thermoelectric materials. The poor stability of n-type organic semiconductors in air and water has proved a roadblock in the development of reliable thermoelectric power generators. We developed a simple green route for preparing n-type carbon nanotubes (CNTs) by doping with cationic surfactants and fabricated films of the doped CNTs using only aqueous media. The thermoelectric properties of the CNT films were investigated in detail. The nanotubes doped using a cationic surfactant (cetyltrimethylammonium chloride (CTAC)) retained an n-doped state for at least 28 days when exposed to water and air, indicating higher stability than that for contemporary CNT-based thermoelectric materials. The wrapping of the surfactant molecules around the CNTs is responsible for blocking oxygen and water from attacking the CNT walls, thus, extending the lifetime of the n-doped state of the CNTs. We also fabricated thermoelectric power conversion modules comprising CTAC-doped (n-type) and sodium dodecylbenzenesulfonate- (SDBS-) doped (p-type) CNTs and tested their stabilities in water. The modules retained 80±2.4% of their initial maximum output power (at a temperature difference of 75°C) after being submerged in water for 30 days, even without any sealing fills to prevent device degradation. The remarkable stability of our CNT-based modules can enable the development of reliable soft electronics for underwater applications.

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Tuning the structure of borane-nitrogen derivatives towards high-performance carbon nanotubes-based n-type thermoelectric materials

Cited by 29 publications

References 57 publications

Promoting the Thermoelectric Performance of Single-Walled Carbon Nanotubes by Inserting Discotic Liquid-Crystal Molecules

Promoting the Thermoelectric Performance of Single-Walled Carbon Nanotubes by Inserting Discotic Liquid-Crystal Molecules

Oxygen-Rich Polymer Polyethylene Glycol-Functionalized Single-Walled Carbon Nanotubes Toward Air-Stable n-Type Thermoelectric Materials

Green Route for Fabrication of Water-Treatable Thermoelectric Generators

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