Model of the external magnetic field effect on the H2O2 reaction on an SnO2 surface

An H2D2 isotope effect on an external magnetic field effect on the hydrogen-oxygen reaction on an SnO2 surface at 775 K was observed. The rate of increase for the external magnetic field effect on the H2O2 reaction was 1.5 times as large as on the D2O2 reaction. This effect strongly suggests that the H2O2 reaction on the SnO2 surface is an Eley-Rideal type reaction. The present results strongly suggest that only the H2O2 reaction via the activated complex OH2− was accelerated by an external magnetic field and that the activated complex of this reaction has a structure in which there is only a weak interaction between undissociated hydrogen molecules and surface-adsorbed O2−. A model is proposed in which the magnetic field affects the electron spin of the quasi-radical pair H · · H in activated complexes, and the recombination of H · · H is inhibited by the singlet-triplet conversion caused by applying an external magnetic field.