Enhanced synthesis of Mg(OH)2 hexagonal nanosheets using Mg powder and H2O2 solution and an observation of its NH3 sensing behaviour at room temperature

Magnesium is one of the most common metals in the Earth’s crust, so Mg(OH)2 nanomaterials made directly from magnesium metal have a wide range of applications. Mg(OH)2 nanosheets can be synthesised directly from Mg powder and H2O2 solution below 200 °C. The thickness of these plates decreases as the sample processing temperature increases. The optical bandgap of the synthesised samples ranges from 5.0 eV to 5.7 eV. At 25 °C, the synthesised Mg(OH)2 nanosheets could detect NH3 gas. The gas sensing mechanism was proposed and discussed, where the Mg(OH)2/H2O structure was considered a p-type semiconductor with the carrier of H3O+. The effects of parameters, such as working temperature and ambient humidity, on the electrical resistance and gas sensing properties of the Mg(OH)2 nanosheets were investigated. The NH3 sensing properties of these materials at room temperature were also compared with those of other nanomaterials.