An alternative, faster and simpler method for the formation of hierarchically porous ZnO particles and their thermoelectric performance. Issue 51 (27th June 2017)

• Record Type: Journal Article
• Authors: Virtudazo, Raymond V. Rivera; Guo, Quansheng; Wu, Rudder; Takei, Toshiaki; Mori, Takao
• Is Part Of: RSC advances. Volume 7:Issue 51(2017)
• Page Start: 31960
• Page End: 31968
• Publication Date: 2017-06-27
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra05067d
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : A thermoelectric figure of merit ( ZT ) of 0.075 at ∼750 K (C) has been achieved, due to the synthesized micro/nanoporous ZnO powder. Abstract : We devised an alternative, faster and simple method to prepare hierarchically nanoporous ZnO powders (NZnO) via a quick interfacial reaction (double emulsion) from the mixtures of zinc nitrate hexahydrate (solution, Zn(NO3 )2 ·6H2 O), n -hexane (C6 H14 ), ammonium bicarbonate (NH4 HCO3 ), Tween 80 (C64 H124 O26 ) and Span 80 (C24 H44 O6 ), which was calcined at 450 °C. Due to the micro/nanopore structures, the obtained NZnO powders had a larger surface area (∼69.7 m 2 g −1 ) than the commercial ZnO powders. For the thermoelectric evaluation, the textured NZnO pellets (T-NZnOP) were prepared by low pressure spark plasma sintering (SPS) using the newly synthesized NZnO powders (NZnO). In this study, the synthesized NZnO powders that were made into T-NZnOP (sample pellets) showed a significantly lower thermal conductivity with distinctive electrical properties when compared to the bulk commercial ZnO powders. The thermoelectric enhancement can be attributed to the nanopore distribution found in the porous T-NZnOP material which demonstrates the potential usefulness of this method for other porous oxide thermoelectric (TE) materials.