fig1

Figure 1. (A) Optical image of discarded cigarette filters. (B) Schematic of preparation process of NCPs/N-NCPs. (C-E) XRD, XPS and FT-IR spectra of CNPs and N-CNPs. (F) TEM image of as-prepared N-CNPs. (G) Nitrogen adsorption/desorption isotherms and pore size distribution (inset) of N-CNPs. (H) X-ray photoelectron spectrum de-convoluted into the N1s of N-CNPs after soaking in the electrolyte.