Multifunctional ZnO-porous carbon composites derived from MOF-74(Zn) with ultrafast pollutant adsorption capacity and supercapacitance properties.

In the present study, the ZnO-porous carbon (ZnO-C) composites were prepared by pyrolyzing MOF-74 (Zn) precursor at different pyrolysis temperatures. The ZnO-C composites were endowed with ultrafast organic dye adsorption capability and promising supercapacitance properties due to the existence of abundant pores within the composite structures. Having a surface area of 782.971 m2/g and pore volume of 0.698 m3/g, the composite pyrolyzed at 1000 °C (ZnO-C1000) exhibited the best performance for organic pollutant uptake. Specifically, 50 mg of ZnO-C1000 could remove all the Rhodamine B dye from 100 mL aqueous solution within 0.5 h even the dye concentration was as high as 40 mg/L. It was also shown that the ZnO-C composites could preserve their adsorption capability in a wide pH range, and keep promising dye adsorption stability after consecutive adsorption/desorption cycles. Furthermore, the ZnO-C900 exhibited a specific capacitance of 197.84 F/g as the supercapacitance electrode with good stability (∼97.8% capacitance retention after 1000 cycles). The overall results indicate that the prepared ZnO-C composites have multi-application potentials which can be utilized as efficient pollutant absorbents as well as electrode materials for supercapacitors.