Doping Ru endows optimized electronic structure of NiCo ₂ O ₄ , which in turn modifies its d-band center towards optimum H* adsorption energy. The as-prepared spinel yields splendid HER, OER and UOR performances.

After hydrogenation or fluorination, the band gap of the ZnO monolayer can be effectively modulated, and a nonmagnetic metal or magnetic half-metal → non-magnetic semiconductor transition can be achieved.

The controllable phase transition temperature in charge doping VO₂ is coupled with changes in the atomic and electronic structures. The current results provide a variable way to tune the VO₂ phase transition temperature through charge doping.