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In most photoactive semiconductors photochemical corrosion, which leads to photoactivity decay, is one of the bottleneck problems for their realistic application. Herein, we will disclose that electron trapping induced proton uptake is a general factor leading to photoactivity decay of nanostructured TiO 2 which is known for its exceptionally high photochemical stability. By using both phenolphthalein and phosphate group with covalent P-O-Ti connections as molecular probes and application of combined electrochemical techniques, the occurrence of electron trapping induced proton uptake and the mechanism of the photoactivity decay are investigated. This research reveals an important but easily overlooked fact, that is, the carriers' kinetics in nanostructured TiO 2 may not be able to reach a steady state. In other words, a stable photocurrent may not be obtained because the photoelectrochemical process will alter the carriers' dynamics continuously, which leads to continuous decay of the photocurrent. This result could be also common with other semiconductors.

The physicochemical nature of phosphate entities incorporated into the alumina substrate and their effects on the catalytic activity and antiaging ability of corresponding Au catalysts for low temperature CO oxidation have been investigated. The addition of phosphorus mainly depresses the catalytic activity and improves the thermal stability of corresponding Au catalysts. However, the catalytic activity is surprisingly recovered with a further improvement in thermal stability of the Au catalyst as calcination temperature of the phosphate-doped Al 2 O 3 increased. Infrared spectroscopy, X-ray photoelectron spectrometery, X-ray diffraction, and N 2 adsorption−desorption isotherm evidenced the important structural and chemical change of P-modified Au catalysts upon calcination temperature. The influence by textural and electronic changes in the catalytic performance of corresponding Au-based catalysts is discussed.

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