SWCNT (XFNANO, Co., Ltd.) was pretreated in 6 mol L -1 HCl solution for 12 h to remove any metal impurities. After that, the SWCNT sample was filtrated, washed with deionized water and freeze-dried. Then 20 mg of the purified SWCNT was subsequently dispersed in 20 ml of DMF using sonication. Then, an appropriate amount of CoPc dissolved in 5 ml DMF was added to the SWCNT suspension. The mixture was sonicated for 30 min to obtain a well-mixed suspension, which was further stirred at room temperature for 24 h. Subsequently, the mixture was centrifuged, and the precipitate was washed with DMF, ethanol and DI water. Finally, the precipitate was lyophilized to yield the final product.