Preparing Tungsten Monoxide Nano Film with Drop Coating Method

Photoelectrochemical cells (PEC) decompose water to produce hydrogen to convert solar energy into chemical energy. It is considered to be a feasible solution to replace the current fossil fuel based energy. Semiconductor material is an important research direction in this field.

Compared with traditional semiconductor materials such as titanium dioxide and iron oxide, tungsten trioxide has a suitable band gap (2.5 eV to 2.9 eV), and the electrode potentials of valence band and conduction band are 3.2 eV and 0.4 eV, respectively. It is O2, and has the advantages of low price, high stability, non-toxicity and light corrosion resistance in acidic and neutral environments. It is an excellent photoelectrochemical decomposition water photoanode material.

At present, the most common preparation methods of tungsten trioxide nanofilms include hydrothermal method, sol-gel method, atomic layer deposition method, electrodeposition method and chemical vapor deposition method. Compared with the high equipment requirements and complex preparation processes of atomic deposition, electrodeposition and chemical vapor deposition, the hydrothermal and sol-gel methods are simpler and have lower temperature requirements. However, the above existing methods cannot prepare tungsten trioxide nanofilms with high photoelectric performance under the premise of low experimental cost, simple operation and high safety.

In order to solve the above technical problems, a tungsten monoxide nano film can be prepared by a drop coating method:

Step 1: The tungsten hexachloride is dissolved in absolute ethanol, and stirred to obtain a precursor solution; the molar concentration of tungsten hexachloride in the precursor solution is 5mmol / L ~ 60mmol / L.

Step 2: Applied 5 μL to 100 μL of the precursor solution surface of the substrate and blow to be dried, and then the substrate is heat at a temperature of 80 ° C to 150 ° C for 3 min to 5 min. Then it is cooling to room temperature.

Step 3: Repeating step 2 until a film layer is obtained on the surface of the substrate;

Step 4: Heating the film layer in the third step to a high temperature of 400 ° C to 550 ° C for 2 h to 6 h, and then a tungsten trioxide nano film is obtained on the surface of the substrate after high temperature calcination.

The above process has a low requirement for equipments. It is simple operation, low cost and high safety performance. What’s more, the prepared tungsten trioxide nano film exhibits excellent photoelectric performance and high stability as a highly efficient photoanode material. It can also be applied to the hydrogen production of photoelectrochemical seawater decomposition, from which the solar energy is efficiently converted into clean energy, alleviating the current global issues of shortage of fossil fuels and serious environmental pollution.

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