(1) Preparation of memristive devices and their applications in non-volatile resistance random access memory (RRAM), neural networks, electronic skin, neuromorphic computing chips, and artificial intelligence. (2) Preparation of new energy storage materials and their applications in secondary rechargeable batteries, photovoltaic devices, self-powered device, and photocatalytic hydrogen production. (3) Using the earth-abundant materials to prepare sustainable, renewable and green electronics.