Nickel-decorated RuO2 nanocrystals with rich oxygen vacancies for high‐efficiency overall water splitting

•Oxygen vacancy-rich Ni-decorated RuO2 (NiRuO2−x) is successfully fabricated by a unique one-pot glucose-blowing approach.•The NiRuO2−x exhibits excellent HER, OER performance and long-term stability in alkaline solutions.•DFT calculations confirm that the addition of nickel atoms and oxygen vacancies leads to the d-band center of RuO2 close to the Fermi energy level, lowering the activation barrier for the reactions of HER and OER.