Bismuth Tungstate-Tetracarboxyphenyl Porphyrin Composite

The photoelectric properties of bismuth tungstate are severely limited by its low quantum efficiency. Therefore, the study of bismuth tungstate composites is an effective way to improve the photoelectric properties. The common practice is to dope materials with complementary effects.

Porphyrins are a class of macromolecular heterocyclic compounds. Modified porphyrins can copolymerize carbon dioxide with epoxides under the co-catalysis of iron, cobalt and aluminium. Some scholars used tetracarboxyphenyl porphyrin as carrier to deposit bismuth tungstate on the carrier to make composite materials. It needs to go through the following process:

1)Preparation of flower-like bismuth tungstate: 0.79g bismuth nitrate pentahydrate and 0.23g sodium tungstate were added into 25 ml of water. The ultrasonic water bath was at 60 ℃, stirred evenly, and the pH was adjusted to 2-2.5. Hydrothermal reaction was carried out in the reactor for 28-30 hours, cooling, washing with secondary water and ethanol respectively. After 10-12 hours of drying, pale yellow solid samples were obtained. The product is bismuth tungstate, and then the product is ground into powder in a mortar and placed for use.

2)Composite materials were prepared by immersion self-assembly method. Firstly, flower-like bismuth tungstate was deposited on FTO conductive glass by electrophoretic deposition. The process of electrophoretic deposition was as follows: 6-8 mg flower-like bismuth tungstate, 2-4 mg iodine and 10-12 ml acetone were mixed. FTO conductive glass was added into the above-mentioned mixture, and DC current was 8-12 V for each. The time of secondary deposition is 2-4 minutes and 2-3 times. After deposition, the FTO conductive glass is dried at 50-60 ℃ for 10-12 hours, and then burned in a tubular furnace at 500 ℃. Then FTO conductive glass was immersed in ethanol solution containing 0.005mmol/L tetracarboxyl phenylporphyrin (TCPP) in dark for 20-24 hours to obtain flower-like bismuth tungstate-tetracarboxyl phenylporphyrin composite loaded on FTO conductive glass.

Because porphyrin has sensitization effect, it can improve light absorption ability and form heterojunction with bismuth tungstate, which can reduce the probability of electron hole recombination. It is proved that the photocurrent of bismuth tungstate-tetracarboxyl phenyl porphyrin composite is four times and six times higher than that of bismuth tungstate, respectively. The lower the probability of electron hole recombination after irradiation, the more effective the photoelectric response of bismuth tungstate is.

• < Prev
• Next >