3D conductive monolithic carbons from pyrolyzed bamboo for microfluidic self-heating system
Layne O.L. Gontijo, Mario Nogueira Barbosa, Druval Santos de Sá, Sônia Letichevsky, Marlin J. Pedrozo‐Peñafiel, Ricardo Q. Aucélio, Ivaní de Souza Bott, Haimon Diniz Lopes Alves, Benjamin Fragneaud, Indhira O. Maciel, André L. Rossi, Letizia Savio, Giovanni Carraro, Anja Došen, F.L. Freire, Ghavami Khosrow, Sidnei Paciornik, Omar Ginoble Pandoli
Abstract
Bamboo, like wood, is a promising natural template for biobased devices that takes advantage of its hierarchical architecture, microarray channels, anisotropic mechanical and electrical properties. Herein we report a low heat thermal treatment (HTT, 700-1000 °C) of natural bamboo specimens to obtain bamboo-based graphitic devices with thermoelectric and electrochemical properties. The preservation of the highly anisotropic architecture of three-dimensional carbon material (3D-CM) allowed adding specific thermoelectric and electrochemical properties depending on the HTT of the pristine specimens. High electric conductivity (σ, 839 S/m) was observed at 1000 °C showing a remarkable potential application as a bamboo-based working electrode. The bamboo annealed to 700 °C showed higher resistivity (ρ, 0.15 Ω m, and σ, 6.6 S/m), thermal conductivity (1.77 W/m K), and thermal heating rates (1.0 °C/s). The pyrolyzed biomass (B-700) was used as a 3D microfluidic heater to heat polar solvents (H2O and ethylene glycol) in flow mode up to their boiling points. A 2D carbon hotplate heater was built-up to warm solvent in batch mode. A complete chemical and physical characterization of the samples allowed us to determine structural and chemical compositions, cellulose crystalline structure phase transition to graphitic/turbostratic carbon, thermal and electrical conductivity of unprecedented bambootronics bio-devices.