Carbonization of MOF-5/Polyaniline Composites to N,O-Doped Carbon/ZnO/ZnS and N,O-Doped Carbon/ZnO Composites with High Specific Capacitance, Specific Surface Area and Electrical Conductivity

Composites of carbons with metal oxides and metal sulfides have attracted a lot of interest as materials for energy conversion and storage applications. Herein, we report on novel N,O-doped carbon/ZnO/ZnS and N,O-doped carbon/ZnO composites (generally named C-(MOF-5/PANI)), synthesized by the carbonization of metal–organic framework MOF-5/polyaniline (PANI) composites. The produced C-(MOF-5/PANI)s are comprehensively characterized in terms of composition, molecular and crystalline structure, morphology, electrical conductivity, surface area, and electrochemical behavior. The composition and properties of C-(MOF-5/PANI) composites are dictated by the composition of MOF-5/PANI precursors and the form of PANI (conducting emeraldine salt (ES) or nonconducting emeraldine base). The ZnS phase is formed only with the PANI-ES form due to S-containing counter-ions. XRPD revealed that ZnO and ZnS existed as pure wurtzite crystalline phases. PANI and MOF-5 acted synergistically to produce C-(MOF-5/PANI)s with high S(BET) (up to 609 m(2) g(−1)), electrical conductivity (up to 0.24 S cm(−1)), and specific capacitance, C(spec,) (up to 238.2 F g(−1) at 10 mV s(−1)). Values of C(spec) commensurated with N content in C-(MOF-5/PANI) composites (1–10 wt.%) and overcame C(spec) of carbonized individual components PANI and MOF-5. By acid etching treatment of C-(MOF-5/PANI), S(BET) and C(spec) increased to 1148 m(2) g(−1) and 341 F g(−1), respectively. The developed composites represent promising electrode materials for supercapacitors.