1. Polyoxometalates: synthesis, structure and applications in catalysis, antibacterial and antitumor bioactivity, etc. 2. Metal-organic frameworks (MOFs) and organic–inorganic hybrid materials: synthesis, structure and applications in catalysis, gas adsorption / separation, sensor and light-emitting device, etc. 3. Polyoxometalate-based materials: synthesis, structure and applications in electrocatalysis, photocatalysis, and organocatalysis.