Radiolysis of water with aluminum oxide surfaces

Aluminum oxide, Al2O3, nanoparticles with water were irradiated with γ-rays and 5MeV He ions followed by the determination of the production of molecular hydrogen, H2, and characterization of changes in the particle surface. Surface analysis techniques included: diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), nitrogen absorption with the Brunauer – Emmett – Teller (BET) methodology for surface area determination, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Production of H2 by γ-ray radiolysis was determined for samples with adsorbed water and for Al2O3 – water slurries. For Al2O3 samples with adsorbed water, the radiation chemical yield of H2 was measured as 80±20 molecules/100eV (1 molecule/100eV=1.04×10−7mol/J). The yield of H2 was observed to decrease as the amount of water present in the Al2O3 – water slurries increased. Surface studies indicated that the α-phase Al2O3 samples changed phase following irradiation by He ions, and that the oxyhydroxide layer, present on the pristine sample, is removed by γ-ray and He ion irradiation. •Water adsorbed on Al2O3 surfaces give greatly enhanced H2 yields.•Water – Al2O3 slurries give H2 yields about double that of pure water.•AlOOH impurities at the surface are reduced to Al2O3.•Al2O3 can be reduced to the Al metal by He ions.