Rooting MnO2 into protonated g-C3N4 by intermolecular hydrogen bonding for endurable supercapacitance

Composited electrode materials for energy storage typically benefit from the merits of each component but meanwhile largely suffer from the vulnerable structural integrity during repetitive cycling. Realizing the merely physical attachment in most composited structures being too weak to survive harsh cycling, we report here a facile one-step synthesis strategy with generation of chemical bonds, more specifically, intermolecular hydrogen bonds, to tightly combine each component. We demonstrate this concept by designing a composite featuring MnO2 nanorods chemically rooted into protonated g-C3N4, where the protonation of 2D g-C3N4 substrate (pg-C3N4), the nucleation/growth of MnO2 and the formation of hydrogen bonding between pg-C3N4 and MnO2 simultaneously occur. The obtained composite, when applied for supercapacitive energy storage, yields maximum specific capacitances of 348.4 F g−1 at a current density of 1.0 A g−1 as well as a high retention of ~85.0% after 10000 cycles at 6.0 A g−1, surpassing most previously reported composited electrode materials based on either MnO2 or g-C3N4. We expect this work to inspire the synthesis of composited electrode materials with consolidated 3D architecture for endurable energy storage performance.