Dimensional Nanoarchitectonics of g-C₃N₄/Co Nanocomposites for Photo- and Electro-Chemical Applications

Cobalt ions were introduced during thermal polymerization at high temperature to prepare graphic carbon nitride (g-C3N4) and Co composites. The interface engineering induced by Co ions resulted in the variation of morphology as well as photo- and electro-chemical performance of the composite samples. Co-g-C3N4 composite samples revealed superior thin-nanosheet and nanotube morphologies at 680 and 750 °C, respectively. As separation centers, Co–N bonds at the interface promoted the transfer of charges and improved photocatalytic properties. Thus, the Co-g-C3N4 composite nanosheets revealed the best photocatalytic performance, in which the maximum degradation rate constant of rhodamine B reached to 0.126 min–1, which was 9.7 times of that of pure g-C3N4 nanosheets. In contrast, the Co-g-C3N4 composite nanotubes with Co nanoparticles effectively enhanced the hydrogen evolution reaction. In the case of a current density of 10 mA cm–2, the overpotential of the Co-g-C3N4 composite nanotubes was 249 mV and the Tafel slope was 80 mV dec–1. In addition, the Co-g-C3N4 composite nanotubes revealed high charge–discharge capacity as a supercapacitor. This result provided a method for building g-C3N4-based photo- and electro-catalysts for various photo- and electro-chemical applications including photocatalytic degradation of organic pollutants, electrocatalytic hydrogen evolution reaction, and supercapacitors.