Figures (6)  Tables (4)

    • Figure 1. 

      Comparison of conventional furnace heating and microwave-assisted activation strategies.

    • Figure 2. 

      Microwave heating system.

    • Figure 3. 

      Microwave heating system and heating characteristics: (a) temperature, (b) microwave absorption power, (c) microwave absorption efficiency, and (d) microwave absorption energy of different samples.

    • Figure 4. 

      The morphology and pore structure of samples: (a) SEM images, (b) N2 adsorption–desorption isotherms, (c) NLDFT pore size distributions of samples, and (d) the micropore volume, meso/macropore volume, and ultramicro volume of samples.

    • Figure 5. 

      Physicochemical structure characterizations: (a) Raman spectrum, (b) Raman spectrum fitted into five bands of CH-0, (c) ID1/IG, (d) EPR spectroscopy, (e) XRD spectrum, (f) FTIR spectrum, (g) deconvoluted N1s spectrum of YYH-300W, (h) deconvoluted O1s spectrum of YYH-300W, (i) nitrogen and oxygen content of samples, (j) nitrogen functional groups distributions, and (k) oxygen functional groups distributions.

    • Figure 6. 

      The adsorption characteristics of CO2. CO2 adsorption isotherms at (a) 0 °C, and (b) 25 °C, (c) the fraction of micropore filling by CO2 ($f_{\rm CO_2} $), (d) the CO2/N2 selectivity at 25 °C and 0–1 bar (the CO2/N2 concentration ratio is 15:85); (e) The isosteric heat of CO2 adsorption; (f) cycle adsorption curve of the sample YYH-250.

    • Sample SBET
      (m2·g−1)      		 Vmicro
      (cm3·g−1)      		 Vtotal
      (cm3·g−1)      		 Vmicro/Vtotal
      (%)      		 Vultramicro
      (cm3·g−1)      		 Vultramicro/
      Vtotal (%)      		 H–K average pore
      size (nm)
      THM-200 767 0.31 0.36 86.62 0.24 66.61 0.70
      THM-250 910 0.36 0.40 91.27 0.29 71.74 0.67
      THM-300 1131 0.46 0.51 89.94 0.35 68.01 0.70
      YYH-200 1057 0.44 0.52 84.76 0.31 59.27 0.70
      YYH-250 1103 0.46 0.55 82.99 0.32 58.73 0.70
      YYH-300 1008 0.42 0.49 84.47 0.30 60.31 0.69

      Table 1. 

      Parameters of pore structure for ACs

    • Sample ID1/IG La (nm) Lc (nm) d002 (nm) Ipeak,EPR
      THM-200 2.83 4.43 0.94 0.38 67,021
      THM-250 2.82 3.40 1.00 0.35 17,736
      THM-300 2.50 3.49 0.95 0.38 5,006
      YYH-200 3.24 4.15 1.03 0.37 41,825
      YYH-250 2.61 3.06 0.92 0.39 23,152
      YYH-300 3.08 3.51 0.97 0.38 8,117

      Table 2. 

      Physicochemical structural parameters of ACs

    • Sample C1s (at.%) O1s (at.%) N1s (at.%) C=O (at.%) C–O (at.%) N-6 (at.%) N-5 (at.%) N-Q (at.%) N-O (at.%)
      THM-200 83.41 12.47 4.12 5.3 6.59 1.22 1.52 0.9 0.48
      THM-250 84.47 11.18 4.34 4.58 5.71 0.97 1.75 1.29 0.33
      THM-300 88.3 8.03 3.67 3.76 3.26 0.94 1.08 1.08 0.56
      YYH-200 80.69 11.95 7.36 6.78 4.43 2.49 2.87 1.07 0.93
      YYH-250 80.55 10.8 8.65 6.3 3.84 3.19 2.72 2.08 0.66
      YYH-300 80.81 10.25 10.06 5.92 3.29 4.29 2.72 2.04 1.01

      Table 3. 

      Nitrogen and oxygen functional group contents of ACs

    • Sample CO2/0 °C CO2/25 °C N2/25 °C ${\boldsymbol f}_{\bf{ CO}_{\bf 2}} $ CO2/N2 selectivity (1 bar)
      THM-200 3.82 2.65 0.23 0.37 65
      THM-250 4.36 2.96 0.25 0.36 68
      THM-300 4.37 3.05 0.34 0.36 50
      YYH-200 4.51 3.01 0.27 0.34 63
      YYH-250 4.72 3.33 0.32 0.32 57
      YYH-300 4.59 3.01 0.29 0.35 58

      Table 4. 

      CO2 adsorption characteristics of ACs