Abstract:A kind of photoelectrode was innovated by anodising titanium mesh in H₂SO₄ solution and photo-reduced in HAuCl₄ solution and named Ti/Au-TiO₂ mesh electrode. The structural and surface morphology of the Ti/Au-TiO₂ mesh was examined by X-ray diffraction, laser Raman spectra, scanning electronic microscopy(SEM) and X-ray photoelectron spectroscopy respectively. The results indicate that its crystal structure, morphology and the size of pore are affected greatly by gold deposition. XPS measurement shows that the valence band of Ti/TiO₂ has two peaks: a wide one at 4.97eV and a narrow one at 6.61eV, which correspond mainly to π(nonbonding) and σ(bonding) O.2p orbitals. The emission intensity of O 2p orbitals becomes stronger and the width of the valence band increases with the increase of Au content. And the emission of nonbonding shifts toward lower binding energy and that of bonding O 2p orbitals shifts toward higher binding energy. The photoelectrocatalytic(PEC) oxidation of humic acid(HA) was investigated in terms of TOC. The PEC oxidation efficiency of Ti/Au-TiO₂ mesh with optimal content of gold is higher than that of Ti/TiO₂ mesh. It is suggested that the recombination of electrons and holes is hindered owing to gold deposition. The investigation shows that PEC oxidation is a convenient way to mineralize organic matter for water treatment.

Key words:   photoelectrocatalytic oxidation; water treatment; humic acid; mesh electrode; gold