Synthesis of Ferrocene‐Modified Carbon Nitride Photocatalysts by Surface Amidation Reaction for Phenol Synthesis

Abstract

AbstractA polymeric Fc‐CO‐NH‐C3N4 (Fc‐CN) material was synthesized by amidation reaction of ferrocenecarboxylic acid (Fc‐COOH) with NH2 groups on the surface of mesoporous graphitic carbon nitride (MCN). The properties of the as‐synthesized samples were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, UV‐Vis diffuse reflectance spectra, N2 adsorption‐desorption isotherm, photoluminescence spectroscopy, transmission electron microscopy, electron paramagnetic resonance, (photo)electrochemical measurement and X‐ray photoelectron spectroscopy. The resultant catalysts were investigated as heterogeneous catalysts for the selective oxidation of benzene to phenol using H2O2 as a green oxidant under visible light irradiation. The results reveal that Fc‐modified samples can not only extend the visible light absorption, but also accelerate the bulk‐to‐surface charge transfer and separation via surface dyadic structures, both of which are favorable for phenol production from benzene photocatalytic hydroxylation with H2O2. Under the optimal conditions, up to 16.9 % phenol yield (based on benzene) is obtained by Fc‐CN/1.5‐5 sample, and the corresponding Fe content is about 0.64 wt%. Furthermore, after the second run, no significant decrease of the activity (in term of TOF) and the selectivity is found in Fc‐CN/1.0‐5 sample. Combined with the experimental results and Fenton‐chemistry, a possible photocatalytic reaction mechanism on the hydroxylation of benzene to phenol at neutral medium with visible light is proposed.