Pyrolyzed carbon with embedded NiO/Ni nanospheres for applications in microelectrodes

Abstract

Photoresist, a frequently used material in existing microfabrication processes, can be utilized in carbon micro electro mechanical system (C-MEMS) since the patterned carbon micro/nano structures can be formed by pyrolysis of a patterned photoresist. These pyrolyzed carbon microstructures have been used as functional and structural units in carbon-MEMS. Compositing and integration with high performance nanostructures is one important strategy for carbon microstructures with applications in microdevices. Herein, we report a patterned microelectrode of pyrolyzed carbon with embedded NiO/Ni nanospheres (carbon/NiO/Ni) fabricated by a novel microfabrication process combing optimized photolithography with pyrolysis. The microsupercapacitors with interdigital carbon/NiO/Ni (C/NiO/Ni) microelectrodes show a high capacitance of 2.75 mF cm⁻². In this microsupercapacitor, the C/NiO/Ni is utilized as the active electrode material and current collector, which makes the microfabrication facile and compatible with micromachining technologies. In addition, the C/NiO/Ni microelectrode pyrolyzed at 900 °C shows a higher capacitance than that of pyrolyzed carbon microelectrodes. The optimized microfabrication process with effectiveness and repeatability shows great potential for fine micropatterning of carbon and electrochemically active materials on a large scale, especially for the microstructuring of a carbon-based composite.