Water splitting and hydrogen emitting catalytic function of hydrogen-implanted oxide ceramics studied using ion beam technology

Temperature dependence of the D-H replacement speed in D-implanted oxide ceramics exposed to H₂ vapor has been studied using the ERD technique. It is found that the D-H replacement speed increases when the exposed specimen is heated above the implantation temperature and the amount of H uptaken by the D-H replacement is almost the same as the implantation amount of D, while both D as-implanted and H uptaken in the replacement are released by heating the specimen in the vacuum. No reduction in the amount of H uptaken by exposure to H₂O vapor at elevated temperatures is ascribed to enough supply of H from the surface due to splitting of H₂O faster than their thermal release. Based on the one way diffusion model of both dipole-induced water splitting at the surface and hydrogen gas emission from the bulk, it is shown that thermal detrapping of D implanted and H replaced in the specimen heated enhances the D-H replacement speed higher than the one extrapolated from the temperature dependence of the D-H replacement speed for the specimens cooled below the implantation temperature, in which the thermal detrapping hardly takes place.