Graphitic carbon nitride modified with Pd nanoparticles toward efficient cathode catalyst for Li-O2 batteries

In this work, graphitic carbon nitride (g-C 3 N 4 ) was modified by Pd nanoparticles (Pd-CN) to prepare an efficient cathode catalyst for Li-O 2 batteries. The specific surface area of g-C 3 N 4 was improved to 239.56[Formula: see text]m 2 /g by two-steps thermal polymerization. Pd nanoparticles were loaded onto the g-C 3 N 4 by K 2 PdCl 4 reduction with NaBH 4 . The resulted Pd-CN composites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscope, and transmission electron microscope. The results proved that g-C 3 N 4 showed three-dimensional layered and porous structure, and Pd nanoparticles were successfully supported on it. The Li-O 2 batteries using Pd-CN composites as cathode catalysts were assembled and tested. The maximum initial discharge specific capacity reached 26,614[Formula: see text]mAh[Formula: see text]g[Formula: see text] at current density of 100[Formula: see text]mA[Formula: see text]g[Formula: see text]. The electrodes remained large capacity under high current density, meaning excellent rate capability. Li-O 2 batteries containing Pd-CN cathode were continuously cycled for 70 cycles with no loss of capacity and obvious change in the terminal voltage. These electrochemical results indicated that the loading Pd nanoparticles effectively increased specific capacity, reduced overpotential and improved the cyclic stability. The Pd-CN composites are proved to be the promising cathode catalysts for Li-O 2 batteries.