;Nowadays, the environmental pollution and enormous consumption of fossil fuel has become a severe problem. Hence, it is urgent to find renewable and clean energy. Since solar energy is inexhaustible, it is regarded as the best candidate to overcome this difficult problem. With the photocatalysts to absorb sunlight, hydrogen can be produced by water splitting. After hydrogen combustion, it only produces energy and water, will not cause damage to the environment. To sum up, the development of photocatalysts with high hydrogen production efficiency is the key to renewable energy. Graphitic carbon nitride (g-C3N4) is n-type semiconductor photocatalyst, which has attracted considerable attention due to its excellent optical and electrical properties. However, a major barrier to g-C3N4 is its high recombination of photogenerated electron–hole pairs. In order to improve this drawback, SiO2@ g-C3N4 core–shell photocatalyst was synthesized by calcining the silica nanoparticle and molten cyanamide in nitrogen atmosphere. The lamellar g-C3N4 was covered on the surface of SiO2, the thickness of g-C3N4 layer was very thin, which could shorten the propagation distance of the photogenerated charges from g-C3N4 bulk to reaction active sites on the surface. This process can inhibit the possibility of photogenerated electron–hole pairs recombination, increasing the hydrogen evolution rate. The catalytic activity of SiO2@ g-C3N4 with different mass ratios of SiO2 and cyanamide calcined has also been investigated. Moreover, the photocatalytic efficiency is optimized by adjusting the concentration of sacrificial reagent.
