Tungsten Disulfide Used in Water-splitting for Hydrogen Production

Tungsten disulfide is a new kind of photocatalyst that has high photocatalytic activity. Such a photocatalyst can be widely used in photocatalytic water-splitting for hydrogen production, because it can effectively improve the utilization of solar energy and hydrogen production rate under visible light.

Solar energy and hydrogen energy are recognized as two new energy sources with low cost, high efficiency and cleanliness. Photocatalytic hydrogen production using solar energy to decompose water and produce hydrogen, which can not only effectively utilize these two new energy sources, but also help solve the problems of energy shortage and environmental pollution.

Tungsten disulfide with layered structure and semiconductor property has abundant active sites as well as suitable band gap.

When it is reduced to a single layer, the indirect band gap of 1.3 eV will be turned into the direct band gap of 2.1 eV. So tungsten disulfide has broad application prospects in photocatalytic water-splitting for hydrogen production.

When used in photocatalytic water-splitting for hydrogen production, tungsten disulfide has the following advantages:

1. The small thickness and large specific surface area make tungsten disulfide have active sites as its own atomic order of magnitude. And tungsten disulfide with two-dimensional lamellar structure can be obtained by various stripping methods.

2. The edges of tungsten disulfide usually have high hydrogen evolution reaction activity. At the earliest time, theoretical calculations suggested that the Gibbs free energy of Mo and S atoms in MoS₂ is close to zero, which is comparable to that of platinum group noble metal catalysts. And this conclusion has been confirmed by most theories and experiments. During the hydrogen evolution with tungsten disulfide, current density (10 mA/cm²) can be achieved under overvoltage between 250 mV and 300 mV, using 0.5 M dilute sulfuric acid.

3. Tungsten disulfide is a graphene-like lamellar material, which helps the formation of composite structure. When tungsten disulfide is loaded on carbon materials, the catalyst’s electrical conductivity will be optimized.

4. Hydrogen evolution reaction activity of tungsten disulfide can be improved by some methods such as providing stress, doping heterogeneity and creating defects.

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