Mechanical Milling Assisted Synthesis of FePc-gCN Nanocomposite Photocatalyst: Dye Degradation, Mechanism and DFT Insights

We present here a mechanochemical method for facile synthesis of Iron phthalocyanine (FePc)- graphitic carbon nitride (gCN) composite with varying weight ratio (1:1, 1:2.5, 1:5) of FePc and gCN. The photocatalytic efficiency of FePc-gCN composite for the elimination of various synthetic dyes, viz, Methylene Blue (MB), Congo Red (CR) and Eosin B (EB) in aqueous media were investigated under visible radiation. The sample with FePc:gCN weight ratio of 1:5 resulted in a removal efficiency of 90 % for MB and 75 % for EB, much higher than their individual counterparts. The synergistic interaction, less charge recombination, and smaller charge transfer resistance in FePc-gCN composite contributed to the superior catalytic performances as confirmed from the impedance spectroscopy and the photoluminescence spectroscopy. Moreover, first principle based DFT calculations on the O2 adsorbed FePc-gCN heterostructure predicted a net transfer of |0.11e| charges from Fe to O atom, favoring the generation of super oxide (O2•−) radicals which contributes actively towards degradation of dye pollutants.