H2 production by γ and He ions water radiolysis, effect of presence TiO2 nanoparticles
Résumé
The effect of TiO2 particles on the yield of H2 formation under water radiolysis is measured. Irradiations were performed using a 60Co γ−ray source as well as with He ions particles (4He2+) generated by a cyclotron with an external beam energy of 6 MeV. The resulting hydrogen as a stable product of radiolysis was measured by mass spectrometry. G(H2) obtained for water radiolysis by He ions−irradiation in aerated and argon water are found to be 1.91 × 10−7 and 1.35 × 10−7 mol J−1, respectively. In the presence of titanium oxide anatase−type dispersed in water, under He ions−irradiation, G(H2) is found to increase slightly from 1.04 × 10−7 to 1.35 × 10−7 mol J−1 by increasing the specific surface from 8 to 253 m2/g, respectively. Under γ-irradiation, G(H2) is found to be 0.41 × 10−7 mol J−1 close to primary yield of hydrogen in presence of OH. Radical scavenger. In addition, radiolysis of water adsorbed in the titanium oxide with low water content, which corresponds to a few layers of water sorbed onto the solid surface gives a huge values of the G(H2). For the same amount of water, with using the dose absorbed by TiO2 particles, for He ions-irradiation, G(H2) increases from 14.5 × 10−7 to 35 × 10−7 mol J-1 by increasing the surface area of TiO2 nanoparticles from 4 to 52 m2/g, respectively. For γ−irradiation G(H2) is found to be 5.25 × 10−7 mol J-1 for the sample with 8 m2/g specific surface area.