Urea-Tris doped 3D graphene for high-stability supercapacitors

The commercialization of supercapacitors hinges critically on developing low-cost electrode materials capable of simultaneously delivering high energy density and long-term stability. To address this challenge, we developed a dual‑nitrogen doping strategy using tris(hydroxymethyl)aminomethane (Tris) and urea to fabricate three-dimensional nitrogen-doped graphene (URNG) through a one-step hydrothermal process. Characterization of the material reveals that the optimized nitrogen conformation of URNG has a 2.07 % increase in pyrrole-N content compared to single nitrogen-source doped graphene (NG), a change that significantly enhances the charge storage capacity while maintaining structural integrity. Electrochemical measurements demonstrate that the assembled symmetric supercapacitor achieves a high energy density of 57.2 Wh·kg⁻¹ at a power density of 670 W·kg⁻¹. The URNG electrodes deliver a specific capacitance of 194.2 F·g⁻¹ at 0.5 A·g⁻¹ (17.1 % higher than NG) while maintaining 87 % capacitance retention after 5000 cycles. The practical applicability of this material was successfully demonstrated by powering a 1.8 V LED device. This work not only provides a facile synthesis strategy but also offers fundamental insights into nitrogen configuration control for advanced energy storage systems.