MnO2 nanowires anchored on mesoporous graphitic carbon nitride (MnO2@mpg C3N4) as a highly efficient electrocatalyst for the oxygen evolution reaction
Abstract In the present study, we report the rational design and fabrication of a novel nanocomposite, namely one dimensional (1D) MnO2 nanowires grew up in situ within the 2D mesoporous carbon nitride (MnO2@mpg C3N4) as a highly efficient electrocatalyst for OER. The structural, morphological and thermal properties of as prepared MnO2@mpg C3N4 electrocatalyst were characterized by TEM, SEM, XRD, XPS, Raman, ICP MS, and TGA. The results clearly revealed the formation of 3D hierarchical heterostructures consisting of 1D MnO2 nanowires anchored on mpg C3N4. Next, the electrocatalytic performance of MnO2@mpg C3N4 nanocomposite was tested in OER wherein it exhibited substantially enhanced activity than pristine 1D MnO2 nanowires. In particular, the turnover frequency (TOF) of MnO2@mpg C3N4 (0.84 s 1@480 mV) was found almost three times higher than that of 1D MnO2 nanowires (0.32 s 1@480 mV) Moreover, the overpotential and Tafel slope values were successfully lowered down by using MnO2@mpg C3N4 nanocomposite compared to those of 1D MnO2 nanowires. It was experimentally demonstrated that the superior OER performance of the MnO2@mpg C3N4 is attributed to the effective stabilization of Mn3+ species (Mn2O3) in the electrocatalyst via the help of nitrogen functional groups of mpg C3N4 and the formation of 3D heterostructure that offers the following three major contributions; i) enhanced aerophobicity due to orientation modifications of growing 1D MnO2 nanowires, ii) open structure facilitating the rapid detachment of gas bubbles from the electrode surface, iii) a large number of transport channels for the penetration of electrolyte, ions and electrons.
International Journal of Hydrogen Energy