Facilitated interfacial charge separation using triphenylamine-zinc porphyrin dyad-sensitized TiO2 nanoparticles for photocatalysis

Abstract

Three triphenylamine (TPA) substituted dichromophoric zinc porphyrins XZP1–3 and a single zinc porphyrin ZP1 have been rationally designed to construct dye-sensitized TiO2 nanoparticles to explore the feasibility of dichromophoric dye design for photocatalysis. TPA, N,N-diphenyl-(1,1′-biphenyl)− 4-amine and a carbazole-diphenylaniline derivative are attached to the meso-position of porphyrin core as the second chromophore. The electronic structure of the porphyrins is studied by density functional theory (DFT) calculations and the dye-sensitized composites are investigated using couples of spectral and electrochemical techniques. XZP2/TiO2 exhibits the smallest charge transfer resistance and the longest electron lifetime among the investigated composites. The same catalyst performs the highest efficiency in photodegradation of both acid black (AB1) and tetracycline (TC) polluted water samples. Electronic paramagnetic resonance and radical quenching experiments reveal that the priority reactive species are superoxide radicals (•O2−) and holes (h+), suggesting the efficient charge separation at the porphyrin-sensitized TiO2 interface. This work demonstrates the facilitated interfacial charge separation using dichromophoric dye-sensitized semiconductor particles for photodegradation and, the insights should aid in dyad design for photocatalysis application.