Controllable synthesis of large-area free-standing amorphous carbon films and their potential application in supercapacitors

Abstract

A new and simple approach is proposed for the first time to fabricate free-standing amorphous carbon films (FS-ACFs) with controllable thickness by ambient pressure chemical vapor deposition (APCVD). The approach uses methane as the carbon source and Ni foil as the catalytic substrate, in which a large number of carbon atoms are trapped by controlling the experimental conditions during the APCVD growth process, and FS-ACFs are obtained by a simple corrosion of the Ni foil after APCVD growth. FS-ACFs having a uniform and continuous morphology with variable sizes over one hundred square centimeters and a controllable thickness of tens to hundreds of nanometers are synthesized by controlling the experimental conditions. Microstructure observations show that FS-ACFs have porous and transparent characteristics, which can be transferred or bent on different substrates, thus allowing for a variety of potential applications in electrochemistry. As a proof of concept, an electrochemical supercapacitor device directly assembled by using the FS-ACF exhibits an ultrashort time constant of 46 μs, a wide frequency range (∼kHz) for capacitive feature, and a good capacitance performance with an area specific capacitance of 0.28 mF cm⁻² at a scan rate of 50 mV s⁻¹. Furthermore, the FS-ACF-based supercapacitor shows a high power density with a maximum volumetric power density of 17.76 W cm⁻³.