Preparation of N-doped graphite oxide for supercapacitors by NH3 cold plasma

Abstract In this work, N-doped graphite oxide (GO-P) was prepared by cold plasma treatment of GO using a mixture of NH 3 and Ar as the working gas. When the ratios of NH 3 :Ar were 1:2, 1:3, and 1:4, the specific capacitances of the GO-P(NH 3 :Ar = 1:2), GO-P(NH 3 :Ar = 1:3), and GO-P(NH 3 :Ar = 1:4) were 124.5, 187.7, and 134.6 F·g −1 , respectively, which were 4.7, 7.1, and 5.1 times that of GO at the current density of 1 A·g −1 . The capacitance retention of the GO-P(NH 3 :Ar = 1:3) was 80% when it was cycled 1000 times. The characterization results showed that the NH 3 cold plasma could effectively produce N-doped GO and generate more active defects. The N/C ratio and the contents of pyridinic nitrogen and graphitic nitrogen of the GO-P(NH 3 :Ar = 1:3) were the highest. These were conducive to providing pseudocapacitance and reducing the internal resistance of the electrode. In addition, the I D / I G of the GO-P(NH 3 :Ar = 1:3) (1.088) was also the highest, indicating the highest number of defects. The results of discharge parameters measurement and in situ optical emission spectroscopy diagnosis of NH 3 plasma showed that the discharge is the strongest when the ratio of NH 3 :Ar was 1:3, thereby the generated nitrogen active species can effectively promote N-doping. The N-doping and abundant defects were the keys to the excellent electrochemical performance of the GO-P(NH 3 :Ar = 1:3). NH 3 cold plasma is a simple and rapid method to prepare N-doped GO and regulate the N-doping to prepare high-performance supercapacitors.