Tungsten Manganese Calcium / Mesoporous Tungsten Trioxide Composite Catalyst

Hydrogen is a clean energy and does not cause any harm to the environment. The earth is rich in water and low in price. Sunlight is an ideal way to convert solar energy into chemical energy.

The reaction of photocatalytic decomposition of water with industrial and practical value is carried out in a photoelectrochemical cell. The 2.5 reaction is the reaction of photocathode water and the oxidation of photo anode water. The reaction process of water oxidation on the photo anode is four electron reaction. Therefore, it is very important to obtain the photocatalyst which can effectively realize the oxidation of oxygen by the photocatalytic oxidation of water.

A kind of tungsten manganese calcium / mesoporous tungsten trioxide composite catalyst, which can be used to prepare the photo anode, has been developed, including the active component I mesoporous tungsten trioxide, the active component II layer manganese calcium oxide, and the composite catalyst can give full play to the catalytic advantage and get the high yield product.

（1）Preparation of mesoporous tungsten trioxide. Under magnetic stirring, adding phosphotungstic acid and 7-8 nm mesoporous silica (KIT-6) into anhydrous ethanol, stirring 1~ 3 h, centrifuging, drying, and calcining 3~6 h at 400~600°C, naturally cooling to room temperature. The obtained solids were then dispersed into hydrofluoric acid (1~5 mol/L), stirring at room temperature for 6 h and centrifugally separated. After washing several times with deionized water, the solid was dried at 10 h for 150 times, mesoporous tungsten trioxide was obtained. The yield was about 80-90%.

（2）Preparation of manganese and calcium oxide. Under the magnetic stirring, a calcium acetate and four manganese acetate were dissolved in the deionized water and slowly added to the KOH aqueous solution (1-10 mol/L). The brown suspension was obtained, then KMnO4 (0.02-0.1 mol/L) was added to the water solution. After continuous stirring, the centrifugation was centrifuged and the solid was washed away from the subwater several times, drying vacuum, and then in argon. The 2~8 h was calcined at a temperature of 300~600°C and the manganese calcium oxide was obtained in a gas tube furnace. The yield was about 90-95%.

（3）Preparation of tungstic manganese calcium / mesoporous tungsten oxide complex catalyst. The mesoporous tungsten oxide and manganese calcium oxide were added into the ball milling tank and dispersed to the deionized water at room temperature for 3-10 h on the star ball mill at room temperature at 300~500 rpm, the ultrasonic reaction was 5-20 H. After the centrifuge separation, after the solid was dried and vacuum, 1~4 h was calcined at 200~600°C in the argon atmosphere tube furnace, the tungsten manganese calcium / mesoporous tungsten trioxide complex can be obtained for the preparation of the photo anode. The yield is about 90-98%.

The catalyst composed of mesoporous tungsten trioxide and layered manganese calcium oxide complex has high photocatalytic activity and stability, and the prepared mesoporous tungsten trioxide and layered manganese calcium oxide formed an island shaped tungsten manganese calcium complex on the surface of the mesoporous tungsten oxide by physical grinding, ultrasonic peeling deposition and high temperature calcination. It can be used as a photocatalytic material for the preparation of photochemical cells. The photocatalytic anode prepared by this composite material has the characteristics of good stability and no pollution to the environment.

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