In this study, porous activated carbon (AC) was prepared from biowaste cherry flowers (CF) using the chemical activating

agents potassium hydroxide (KOH), sodium hydroxide (NaOH), and zinc chloride (ZnCl2) to capture CO2under ambient

conditions. Among them, the CF-AC: KOH (1:2) sample showed the highest surface area of 1311 m2/g, pore volume of 0.74

cm3/g with high CO2adsorption uptake of 4.0 mmol/g and CO2/N2 selectivity of 28 at 298 K. To further enhance CO2

captureperformance, nitrogen (N)-containing functional groups were introduced by mixing different weight percentages of melamine

(M) or adenine (A). Melamine-doped CF-AC/K/M-1-2-1 demonstrated the highest CO2adsorption capacity of 4.9 mmol/g

or CO2/N2 selectivity of 38 at 298 K. Furthermore, the adsorbent material showed consistent CO2

adsorption performance over ten consecutive CO2 adsorption–desorption cycles by a temperature swing process. This finding highlights that a combination of both chemical activation and N-doping provides a sustainable strategy for the development of high-performance adsorbents derived from bio-waste for the CO2 capture application. The synthesized ACs were characterized using the

Brunauer–Emmett–Teller (BET) method for surface area, pore volume, and pore distribution; scanning electron microscopy

(SEM) for particle morphology; and X-ray fluorescence for chemical composition analysis (XRF) of raw cherry flowers. The

surface element atomic concentrations and binding energies were analyzed using X-ray photoelectron spectroscopy (XPS).