Tuning the Laser‐Induced Processing of 3D Porous Graphenic Nanostructures by Boron‐Doped Diamond Particles for Flexible Microsupercapacitors

Abstract Carbon (sp 3 )‐on‐carbon (sp 2 ) materials have the potential to revolutionize fields such as energy storage and microelectronics. However, the rational engineering and printing of carbon‐on‐carbon materials on flexible substrates remains a challenge in wearable electronics technology. This study demonstrates the scalable fabrication of flexible laser‐induced graphene (LIG)‐boron doped diamond nanowall (BDNW) hybrid nanostructures for microsupercapacitors. Direct laser writing on polyimide film is tuned by the presence of BDNW powder where an appreciable absorbance of the BDNWs at the CO 2 laser wavelength enhances the local film temperature. The thermal shock due to laser irradiation produces graphitized and amorphous carbon at the diamond grain boundaries which increases the thermal and charge transfer capacity between the LIG–diamond interfaces. The samples are further treated with O 2 plasma to tune the wettability or to improve the microsupercapacitor device performance. The outstanding electrical characteristics of graphene, exceptional electrochemical stability of diamond, and essential contributions of oxygen‐containing groups result in a remarkable charge storage capacity (18 mF cm −2 @ 10 mV s −1 ) and cyclic stability (98% retention after 10 000 cycles) outperforming most state‐of‐the‐art LIG‐based supercapacitors. Furthermore, despite extreme mechanical stress, these microsupercapacitors maintain their outstanding electrochemical properties, thus holding promise for high‐power, flexible/wearable electronics.