Synthesis of phthalocyanine/C3N4 structures and investigation of photocatalytic activities in the oxidation reaction of 4-nitrophenol

Abstract

Photocatalytic oxidation is an advanced oxidation technique widely preferred for the removal of pollutants in wastewater. In this work, paramagnetic metallo-phthalocyanines EB2 and EB3 (Co(II)phthalocyanine and Cu(II)phthalocyanine) have been synthesized and characterized. They were interfaced with C3N4 (graphitic carbon nitride) to prepare metallophthalocyanines/C3N4 structures (EB2-C3N4 and EB3-C3N4) using ultrasonic methods. New structures were identified with FT-IR, SEM and TGA. The photocatalytic performances of EB2-C3N4 and EB3-C3N4 for reaction with p-nitrophenol (p-NP) were established. The product selectivity for industrially important benzaldehyde was 85.1% for EB2-C3N4 and 80.6% for EB3-C3N4. EB2-C3N4 showed good potential for p-NP photocatalyic oxidation with high turn-over number (TON) and turn-over frequency (TOF) (390 and 1565) over 15 min. Upon excitation of EB2-C3N4 and EB3-C3N4 with light, 4-nitrophenol was easily reduced to hydroquinone, prompted by electron transfer from C3N4 to phthalocyanine and from phthalocyanine to 4-nitrophenol. Computational investigations were used to determine the energies of the highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO) of EB2, EB3 and C3N4.