TPFC2, TPFE2 and TPFCE2 pellets possessed the absorbances at 700 nm of 0.27–0.29, 0.30–0.33 and 0.58–0.90, respectively, when the reaction time was 10–50 min (Fig. 2a–c), while the absorbances at 700 nm of TPFC2, TPFE2 and TPFCE2 sheets were 0.23–0.27, 0.28–0.31 and 0.39–0.60, respectively (Fig. 2d–f).