The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide(TiO_2)was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone,...The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide(TiO_2)was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone,formic acid and acetic acid. Although the direct photocatalytic reduction of arsenate to arsenite with TiO_2 was impossible, an indirect reduction of As(V) was possible in the presence of sacrificial electron donors to form strongly reductive radicals. The addition of ethanol was very effective for indirect photocatalytic reduction of As(V) in aqueous solution with TiO_2 photocatalyst. The indirect photocatalytic reduction rate of As(V) may be related with both the reaction rate constants of reaction of hydroxyl radicals with hole scavenger and the reactivities for the radicals M· which are produced by the reaction of ·OH with hole scavenger.展开更多
The chemical reduction of CO2 remains a challenge with respect to the reversal of the oxidative degradation of any organic materials. The conversion of CO2 into useful substances is essential in developing alternative...The chemical reduction of CO2 remains a challenge with respect to the reversal of the oxidative degradation of any organic materials. The conversion of CO2 into useful substances is essential in developing alternative fuels and various raw materials for different industries. This also aids in preventing the continuous rise in tropospheric temperature due to the green house effect of CO2. In this article an overview of the growth taken place so far in the field of CO2 chemical reduction is pre- sented. The discussion comprises of photochemical methods for the development of different products, viz. CO, CH3OH and CH4, through chemical reduction of CO2. This includes the use of photo catalysts, mainly TiO2, and the role of a hole scavenger （such as 2-propanol） for this purpose.展开更多
Nitro-aromatic compounds can be photocatalytically reduced into the corresponding amine-aromatic com- pounds using TiO2 as a photocatalyst in the UV/TiO2/holes scavenger and Vis/TiO2/dye-sensitized systems. In the UV/...Nitro-aromatic compounds can be photocatalytically reduced into the corresponding amine-aromatic com- pounds using TiO2 as a photocatalyst in the UV/TiO2/holes scavenger and Vis/TiO2/dye-sensitized systems. In the UV/TiO2/holes scavenger system, reaction substrate alcohols such as methanol could be used as the holes scavengers, and in the Vis/TiO2/dye-sensitized system, substrate alcohols could be oxidized to the corresponding aldehydes with high selectivity. When methanol was used as the holes scavengers and the illumination time was 6 h, 87.2% ofp-nitrotoluene could be photocatalytically reduced into p-toluidine. In the Vis/TiO2/dye-sensitized system, the effect of aromatic alcohols for the photocatalytic reduction of nitrobenzene was better than that of other alcohols At the same time, aromatic alcohols can be easily oxidized, and the production efficiencies of the corresponding aldehydes were higher than those of other alcohols. The possible reaction mechanisms were also proposed.展开更多
文摘The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide(TiO_2)was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone,formic acid and acetic acid. Although the direct photocatalytic reduction of arsenate to arsenite with TiO_2 was impossible, an indirect reduction of As(V) was possible in the presence of sacrificial electron donors to form strongly reductive radicals. The addition of ethanol was very effective for indirect photocatalytic reduction of As(V) in aqueous solution with TiO_2 photocatalyst. The indirect photocatalytic reduction rate of As(V) may be related with both the reaction rate constants of reaction of hydroxyl radicals with hole scavenger and the reactivities for the radicals M· which are produced by the reaction of ·OH with hole scavenger.
文摘The chemical reduction of CO2 remains a challenge with respect to the reversal of the oxidative degradation of any organic materials. The conversion of CO2 into useful substances is essential in developing alternative fuels and various raw materials for different industries. This also aids in preventing the continuous rise in tropospheric temperature due to the green house effect of CO2. In this article an overview of the growth taken place so far in the field of CO2 chemical reduction is pre- sented. The discussion comprises of photochemical methods for the development of different products, viz. CO, CH3OH and CH4, through chemical reduction of CO2. This includes the use of photo catalysts, mainly TiO2, and the role of a hole scavenger （such as 2-propanol） for this purpose.
基金Project supported by the National Natural Science Foundation of China （Nos. 20673042, 20973071） and the Key Project of Science and Technology Research of Ministry of Education of China （208062）.
文摘Nitro-aromatic compounds can be photocatalytically reduced into the corresponding amine-aromatic com- pounds using TiO2 as a photocatalyst in the UV/TiO2/holes scavenger and Vis/TiO2/dye-sensitized systems. In the UV/TiO2/holes scavenger system, reaction substrate alcohols such as methanol could be used as the holes scavengers, and in the Vis/TiO2/dye-sensitized system, substrate alcohols could be oxidized to the corresponding aldehydes with high selectivity. When methanol was used as the holes scavengers and the illumination time was 6 h, 87.2% ofp-nitrotoluene could be photocatalytically reduced into p-toluidine. In the Vis/TiO2/dye-sensitized system, the effect of aromatic alcohols for the photocatalytic reduction of nitrobenzene was better than that of other alcohols At the same time, aromatic alcohols can be easily oxidized, and the production efficiencies of the corresponding aldehydes were higher than those of other alcohols. The possible reaction mechanisms were also proposed.
