Lattice defective and N, S co-doped carbon nanotubes for trifunctional electrocatalyst application.

Multifunctional electrocatalysts are desirable for overall water splitting and zinc-air batteries. In this work, N, S co-doped carbon nanotubes (CNT-NS) with a plentiful of defects were obtained through a novel molecular-level codoped and lattice defect construction method. Thiamine hydrochloride and thiocarbamide were adopted as new precursors in situ doping N and S into multi-walled CNTs surfaces, and lattice defects were constructed by in situ chemical etching using ammonium chloride and ammonium bicarbonate. These surface defects and N,S biatom co-doping synergistic effects can accumulate the CNT-NS to exhibit the superior behavior for electrocatalysis of water splitting and zinc-air batteries. The overpotential for overall water splitting was 1.61 V and the specific capacity for zinc-air batteries was 781 mA h g−1, which was superior to previous works. According to the Operando Raman spectroscopy measurements, the S atoms can serve as the intrinsic catalytic sites for HER and OER, and the defective CNT structures could enhance the catalytic kinetics by the electron-transfer process. Further, density functional theory (DFT) results also indicated the contribution of binary atoms co-doping for low ΔG H∗ values. Therefore, this work provides the valuable reference for rational design/construction for metal-free catalysts of overall water splitting. [Display omitted] • CNT-550-NS were successfully prepared through a molecular-level codoped and lattice defect construction method. • CNT-550-NS exhibited a plentiful of defective structure on the carbon nanotubes surfaces. • CNT-550-NS possessed a high contents of heteroatoms of N and S. • CNT-550-NS executed a remarkable performance for HER, OER and ORR. [ABSTRACT FROM AUTHOR]