Tungsten Oxide Electronic Performance Improvement Method

Tungsten oxide is one of the most studied n-type semiconductor photocatalysts and can be widely used in organic dye degradation, water oxidation, water cracking and carbon dioxide reduction. Tungsten oxide materials have a narrower band gap of about 2.2-2.8 eV, which is affected by morphology and stoichiometric properties.

Conventional tungsten oxide materials have disadvantages such as slow hole dynamics, slow charge transfer at the semiconductor / electrolyte interface, and rapid photo-electron-hole coincidence. As a result, researchers have explored ways to improve light absorption, charge transfer, and charge separation, including morphology control, porous structure construction, heterostructure construction, supported catalysts and doping.

Doping other impurities is a common way to improve the electronic properties of tungsten oxide. Studies have shown that doping impurities can improve the bandgap of tungsten oxide, thereby increasing its visible light absorption range. Doping sulfur and iodine into tungsten oxide increases its visible light harvest. They further found that sulfur / tungsten oxide as a shallow impurity shows greater absorption of visible light, while addition of iodine produces an impurity band that is detrimental to the photocatalytic reaction. Not only the element doping, doping small molecules are also common. Nitrogen / tungsten oxide with a stable sandwich structure was prepared in such a way that nitrogen was trapped in the tungsten oxide structure. The insertion of nitrogen reduces the tungsten oxide bandgap to 1.9 e V, extending the visible absorption range. Spectroscopy and calculations show that the weak interaction between nitrogen and tungsten oxide deforms the host lattice of tungsten oxide, eventually resulting in a red shift of light absorption. The results show that the electrocatalytic activity of the 0.039 nitrogen-tungsten oxide anode material reaches nearly 100% at a wavelength of ≤640 nm and shows good photocatalytic activity.

The generation of oxygen vacancies on the surface of the tungsten oxide material is also an effective means of increasing its photocatalytic activity. Oxygen vacancy in tungsten oxide as a shallow donor can significantly improve its conductivity and donor density. The tungsten oxide is sintered in a hydrogen atmosphere to introduce oxygen vacancies therein. Compared with stoichiometric tungsten oxide, the hydrogen treated tungsten oxide photocurrent has an order of magnitude increase and exhibits excellent stability.

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