Chemically induced dynamic polarization by magnetic field on nanoionic photocatalysis via 2-propanol oxidation

Abstract

Heterogenous photocatalysis has emerged as a sustainable and environmentally benign strategy since it converts solar energy into chemical energy. Though more research is exploring the magnetic field effect on photocatalysis, the mechanism is still ambiguous. Magnetic field-assisted and electric-assisted photocatalytic reactions were investigated in this study. In the first magnetic field-assisted experiment, the magnetic field effect on heterogenous photocatalysis was explored with TiO2 and Pt/TiO2. Isopropanol photocatalytic oxidation reaction was conducted. Two levels of dissolved oxygen concentration, magnitude of magnetic flux density and temperature were studied. The magnetic field positive effect was prominent, especially under higher dissolved oxygen concentration and greater magnitude of a magnetic field. For Pt/TiO2 photocatalyst at 10 o C and dissolved oxygen concentration over 20 ppm, 450 Gauss increased isopropanol photooxidation by 10%, while 900 Gauss enhanced by 21%. For TiO2 photocatalyst at 10 o C dissolved oxygen concentration over 20 ppm, 450 Gauss has no prominent effect, while 900 Gauss enlarged 18% isopropanol photooxidation. The statistical analysis demonstrated that dissolved oxygen with magnetic flux density interaction and DO were the top two influencing elements. The hyperfine mechanism results from the interaction between the electron spins with nuclear spins in atoms. It depends on the elements and the dwelling time of unpaired electrons with its nucleus. The mechanism would contribute to singlet (S) ⇄ triplet (T) intersystem crossing. It was possibly because the net Lorentz force acting on paramagnetic oxygen molecule and singlet-triplet intersystem crossing by magnetic field led to the enhancement of the photooxidation of isopropanol.