Converting natural diatomite into nanoporous silicon for eco-friendly thermoelectric energy conversion. (15th September 2018)

• Record Type: Journal Article
• Authors: Zong, Peng-an; Makino, Daiki; Pan, Wei; Yin, Shujia; Sun, Chuan; Zhang, Peng; Wan, Chunlei; Koumoto, Kunihito
• Is Part Of: Materials & design. Volume 154(2018)
• Page Start: 246
• Page End: 253
• Publication Date: 2018-09-15
• Subjects: Thermoelectric -- Silicon -- Diatomite -- Nanocrystallization -- Porosification; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2018.05.042
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Thermoelectric generators are one type of clean energy technologies, capable of converting heat to electricity with no pollution discharge. However, the component elements of the traditional thermoelectric materials are usually rare or toxic. Silicon is non-toxic and abundant, but has too high a thermal conductivity for generation of a temperature gap. Herein, nanocrystallization and nanoporosification are concurrently realized via a thermite reaction based on naturally abundant and eco-friendly diatomite. The thermal conductivities of the nanoporous Si nanobulk are depressed by 2 orders of magnitude compared to that of single-crystal Si, due to significantly enhanced phonon scattering, as the size of the nanograins (~40 nm) and nanopores (~100 nm) are close to the mean free path of the majority phonons. The maximum output power density is 1.14 and 1.81 Wm −2 for n and p -Si single legs under a temperature difference of 40 K, suggesting great potential for use in eco-friendly devices that can harvest electricity from waste heat. Graphical abstract: Unlabelled Image Highlights: Nanoporous Si nanobulks were obtained based on eco-friendly diatomite. The sizes of nanograins and pores are close to Si majority phonon mean free path. The lattice thermal conductivity of Si was depressed as low as ~10 Wm −1 K −1 . The maximum output power density is 1.81 Wm −2 for p -Si single leg under ∆ T = 40 K.