Nitrogen-incorporated boron-doped diamond films for enhanced electrochemical supercapacitor performance

The electrochemical (EC) supercapacitor, known for its rapid charging, reliability, and versatile applications, demands optimized electrode characteristics and an understanding of their electrochemical behaviour. Although boron-doped diamond (BDD) holds promise as a supercapacitor electrode, a crucial gap exists in comprehending its material behaviour under specific growth conditions. Here, nitrogen-incorporated BDD (N-BDD) films with different microstructures are investigated. The morphology of N-BDD films is varied by tuning the substrate temperature (Ts) from 400 °C to 850 °C during the growth process. The diamond films grown at lower Ts = 400 °C consist of faceted grains, and the grain sizes shrink as Ts is increased (550 °C and 700 °C). Interestingly, the films grown at 850 °C (N-BDD850°C) show nanowire-like morphology with enhanced electrical conductivity. The spectroscopy and microscopy results reveal the concurrence of sp3-diamond and sp2-graphitic phases in the nanowire morphology. The EC supercapacitor studies disclose that formation of nanowire-like morphology for N-BDD850°C increases the active surface area and electron transport properties; hence, higher current response and enhanced specific capacitance (0.09 F cm−2 at a current density of 1.53 mA cm−2) are observed. Lifecycle stability of 82% is observed after 5000 cycles indicating the efficient performance of N-BDD850°C films.