3 years ago

Giant Peak Voltage of Thermopower Waves Driven by the Chemical Potential Gradient of Single-Crystalline Bi2Te3

Giant Peak Voltage of Thermopower Waves Driven by the Chemical Potential Gradient of Single-Crystalline Bi2Te3
Seunghyun Baik, Swati Singh, Hyeona Mun, Sanghoon Lee, Sung Wng Kim
The self-propagating exothermic chemical reaction with transient thermovoltage, known as the thermopower wave, has received considerable attention recently. A greater peak voltage and specific power are still demanded, and materials with greater Seebeck coefficients have been previously investigated. However, this study employs an alternative mechanism of transient chemical potential gradient providing an unprecedentedly high peak voltage (maximum: 8 V; average: 2.3 V) and volume-specific power (maximum: 0.11 W mm−3; average: 0.04 W mm−3) using n-type single-crystalline Bi2Te3 substrates. A mixture of nitrocellulose and sodium azide is used as a fuel, and ultraviolet photoelectron spectroscopy reveals a significant downshift in Fermi energy (≈5.09 eV) of the substrate by p-doping of the fuel. The induced electrical potential by thermopower waves has two distinct sources: the Seebeck effect and the transient chemical potential gradient. Surprisingly, the Seebeck effect contribution is less than 2.5% (≈201 mV) of the maximum peak voltage. The right combination of substrate, fuel doping, and anisotropic substrate geometry results in an order of magnitude greater transient chemical potential gradient (≈5.09 eV) upon rapid removal of fuel by exothermic chemical reaction propagation. The role of fuel doping and chemical potential gradient can be viewed as a key mechanism for enhanced heat to electric conversion performance. A giant peak voltage of thermopower waves (maximum: 8 V; average: 2.3 V) is obtained by the fuel doping and chemical potential gradient of single-crystalline Bi2Te3. The role of the chemical potential gradient, which is more than an order of magnitude greater than the Seebeck effect, can be viewed as a key mechanism for enhanced heat-to-electric conversion performance.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adma.201701988

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