Silver Carbonate-Silver-Tungsten Trioxide Ternary Composite Photocatalyst

The application of semiconductor photocatalyst in the degradation of toxic and harmful organic pollutants is of great significance for solving environmental pollution. However, broadband gap and low quantum efficiency are still the "bottlenecks" of photocatalysts.

Silver carbonate/silver/tungsten trioxide ternary composite photocatalyst is a new type of Z-type photocatalyst. The structure of the catalyst is silver carbonate as carrier, tungsten trioxide is modified on silver carbonate, and silver is loaded on tungsten trioxide. The preparation of this catalyst involves the following steps:

(1)The dilute nitric acid solution was obtained by adding 5 mL concentrated nitric acid droplets with 65% mass fraction into 25 mL deionized water under stirring conditions for 10 minutes; then the dilute nitric acid solution was mixed with 10 mL Na₂WO₄·2H₂O solution (containing 1.5 mmol Na₂WO₄·2H₂O) to form a light yellow solution, and stirred for 1 hour to obtain the slurry; finally, the slurry was transferred to a 50 mL stainless steel autoclave. Tungsten trioxide nanosheets, named WO₃, were prepared by hydrothermal reaction at 180 ℃ for 3 hours after cooling, centrifugation, deionized water and ethanol cleaning and drying.

(2)The tungsten trioxide nanosheets in step (1) of 305.5 mg were dispersed in 15 mL deionized water by ultrasound for 0.5 h to obtain tungsten trioxide dispersion solution.

(3)50 mg silver nitrate was dissolved in 4 mL deionized water, then the obtained silver nitrate solution was added to the tungsten trioxide dispersion obtained by step (2) and agitated for 0.5 h under dark conditions to obtain Ag+WO₃ dispersion.

(4)The Ag+WO₃ dispersion was prepared by adding 5 mL sodium bicarbonate solution with a concentration of 0.05 mol/L drop by drop into step (3). After stirring for 2 hours, the silver carbonate-silver-tungsten trioxide ternary composite photocatalyst was obtained by irradiating the xenon lamp with a light intensity of 100 mW cm-2 for 10 minutes.

The Z-type silver carbonate-silver-tungsten trioxide ternary composite photocatalyst has the advantages of high photogenerated electron-hole separation efficiency, high photocatalytic activity, strong redox ability, good stability and corrosion resistance. It can degrade dye wastewater and antibiotic wastewater with high efficiency. The synthesis method is simple, the cost of raw materials is low, the energy consumption is low, the time consumption is short and the conditions are easy to control. It is suitable for continuous large-scale photocatalyst. Large-scale batch production has good practical application prospects.

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