Surfactant-assisted fabrication of prussian blue analogs as bifunctional electrocatalysts for water and hydrazine oxidation

Abstract

The development of multifunctional catalysts for sustainable and proficient utilization of chemical energy is the utmost demand of the time. Water and hydrazine are auspicious energy carriers because of their high hydrogen content and henceforth can be employed as chemical hydrogen storage materials or as fuels for the direct fuel cells. In the present study, cationic surfactant-assisted Prussian blue analogs (PBAs) i.e., Mx[Fe(CN)5(N2C6H4)]·yC19H34NBr abbreviated as SF[Fe-CNPy-M]; SF = N-tridecyl-3-methylpyridinium bromide and M = manganese (Mn), cobalt (Co) and nickel (Ni), are synthesized and utilized as bifunctional heterogeneous OER and HzOR electrocatalysts under mild reaction conditions. The synthesis of electrocatalysts is confirmed by spectroscopic techniques i.e., Fourier transforms infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis, and X-ray photoelectron spectroscopy (XPS). The electrochemical measurements reveal an increase in current density, electrochemical surface area and catalytic stability compared to the reported PBAs for OER and HzOR. Among all the synthesized PBAs, SF[Fe-CNPy-Co] displays better electrochemical activity towards OER with 101 mV·dec−1 Tafel slope and appreciably low overpotential value of 470 mV to attain the current density of 10 mA.cm−2. SF[Fe-CNPy-Co] is further tested for HzOR and the results show that it exhibits high activity with the diffusion coefficient of 3.55 × 10−6 cm2.s−1 and rate constant of 3.411× 10−4 cm.s−1. This work proposes a pristine pathway to formulate efficient bifunctional electrocatalysts employing surfactant-assisted pentacyanoferrates-based PBAs for OER and HzOR.