Highly efficient photocatalytic $CO_2$ reduction using 3D heterosystem of carbon foam and graphitic carbon nitride

Abstract

Graphitic carbon nitride, $g-C_3N_4$, is a promising organic photocatalyst for $CO_2$ reduction because of its visible light responsive and thermo-chemically stable properties. However, its high recombination rate and ordinary $CO_2$ adsorption ability have restricted its photocatalytic activity. In this paper, we have fabricated a dual photocatalyst system composed of 3D conductive carbon(carbon foam), derived from a commercial melamine sponge, and $g-C_3N_4$ with a facile preparation method to enhance the $CO_2$ photo-reduction activity. Carbon foam not only functions as a backbone for $g-C_3N_4$ to grow on but also collects photo-induced electrons from $g-C_3N_4$ and provides $CO_2$ adsorption sites. As a result, our system exhibited the CO production rate of 0.853 $\mu mol/g \cdot hr$ resulting from $CO_2$ photo-reduction under visible light irradiation. This rate is 3.72 times and 4.47 times higher than those from pure $g-C_3N_4$and pure carbon foam, respectively. This enhanced activity is ascribed to the repression of excited electrons-holes recombination and increased $CO_2$ adsorption capacity by amine-containing carbon foam.