A kind of photoelectrode was innovated by anodising titanium mesh in H 2SO 4 solution and photo reduced in HAuCl 4 solution and named Ti/Au TiO 2 mesh electrode. The structural and surface morphology of the Ti/Au TiO ...A kind of photoelectrode was innovated by anodising titanium mesh in H 2SO 4 solution and photo reduced in HAuCl 4 solution and named Ti/Au TiO 2 mesh electrode. The structural and surface morphology of the Ti/Au TiO 2 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/TiO 2 has two peaks: a wide one at 4.97 eV and a narrow one at 6.61 eV, 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 TiO 2 mesh with optimal content of gold is higher than that of Ti/TiO 2 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.展开更多
With an attempt to investigate the effect of gold impurity and tungsten oxide on the recombination and separation of electron hole pairs, and disclose the effect of surface state on the photo catalytic activity of TiO...With an attempt to investigate the effect of gold impurity and tungsten oxide on the recombination and separation of electron hole pairs, and disclose the effect of surface state on the photo catalytic activity of TiO 2, an innovative photo catalyst 3%WO 3/0.5%Au 3+ /TiO 2 was prepared by means of sol gel method. The photo oxidation efficiency of photo catalyst was evaluated by conducting a set of experiments to photo degrade methylene blue (MB) in aqueous solution. The surface state properties were examined by means of surface photovoltage spectra (SPS) and electron field induced SPS (EFISPS). The experiments demonstrate that the strongest peak is attributed to electron excited from valence band to conduction band and the second strongest peak is attributed to electron excited from valence band to oxygen molecular for all samples. Electron is trapped by O 2 absorbed on the surface of TiO 2. And the surface state of O - 2 forms. For (1%, 3%)Au 3+ /TiO 2 sample, two new peaks that significantly present at 414?nm and 400?nm respectively should be attributable to gold impurity energy level. And for tungsten oxides doping samples, 4 peaks that significantly present in the region of 500～800?nm should be attributable to tungsten impurity energy level. The intensity of EFISPS decreases with increasing the content of gold ion or tungsten oxide when its content is no more than their optimal dosage. However, when the content of gold ion or tungsten oxide is more than their optimal dosage, impurity energy level becomes recombination center from separation center and the intensity of all peaks increases for them.展开更多
文摘A kind of photoelectrode was innovated by anodising titanium mesh in H 2SO 4 solution and photo reduced in HAuCl 4 solution and named Ti/Au TiO 2 mesh electrode. The structural and surface morphology of the Ti/Au TiO 2 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/TiO 2 has two peaks: a wide one at 4.97 eV and a narrow one at 6.61 eV, 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 TiO 2 mesh with optimal content of gold is higher than that of Ti/TiO 2 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.
文摘With an attempt to investigate the effect of gold impurity and tungsten oxide on the recombination and separation of electron hole pairs, and disclose the effect of surface state on the photo catalytic activity of TiO 2, an innovative photo catalyst 3%WO 3/0.5%Au 3+ /TiO 2 was prepared by means of sol gel method. The photo oxidation efficiency of photo catalyst was evaluated by conducting a set of experiments to photo degrade methylene blue (MB) in aqueous solution. The surface state properties were examined by means of surface photovoltage spectra (SPS) and electron field induced SPS (EFISPS). The experiments demonstrate that the strongest peak is attributed to electron excited from valence band to conduction band and the second strongest peak is attributed to electron excited from valence band to oxygen molecular for all samples. Electron is trapped by O 2 absorbed on the surface of TiO 2. And the surface state of O - 2 forms. For (1%, 3%)Au 3+ /TiO 2 sample, two new peaks that significantly present at 414?nm and 400?nm respectively should be attributable to gold impurity energy level. And for tungsten oxides doping samples, 4 peaks that significantly present in the region of 500～800?nm should be attributable to tungsten impurity energy level. The intensity of EFISPS decreases with increasing the content of gold ion or tungsten oxide when its content is no more than their optimal dosage. However, when the content of gold ion or tungsten oxide is more than their optimal dosage, impurity energy level becomes recombination center from separation center and the intensity of all peaks increases for them.
