Zinc-based zeolitic benzimidazolate framework/polyaniline nanocomposite for electrochemical sensing of hydrogen gas

Abstract Herein, we report on the in-situ chemical polymerization of polyaniline (PANI) doped with zinc-based zeolitic benzimidazolate framework (ZnZIF) to fabricate the PANI-ZnZIF composite for electrochemical hydrogen gas sensing. Fourier-transform infrared and Raman studies of PANI-ZnZIF composite revealed the presence of functional groups corresponding to both ZnZIF and PANI. Both X-ray diffraction and simultaneous thermal analyses showed the co-existence of both PANI and ZnZIF in the composite supported by the decrease in crystallite size and the improvement in the thermal stability, respectively. The scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction revealed that PANI nanofibers wrapped the cube nanofiber-like structures of ZnZIF. The square wave voltammetry, cyclic voltammetry (CV) and chronoamperometry presented good electrochemical performance indicated by an increase in current response with 3 wt% loading of ZnZIF. The high electrochemical current response is due to extraordinary specific surface area, more accessible active sites available for the electrolyte provided by ZnZIF and high conductivity supplied by PANI. Moreover, Tafel parameters and Turnover frequency values derived from CV showed an improvement in the catalytic hydrogen evolution of PANI-ZnZIF composite. The resulting PANI-ZnZIF composite was found to be highly responsive to hydrogen gas as indicated by higher current response and sensitivity (10.8 μA mM H 2 ), faster steady state response time of 4 s accompanied by lower detection limit of 5.27 μM as compared to pure PANI.