For industrial water electrolysis, the development of active and stable catalysts for the oxygen evolution reaction remains a challenge. Here, we report a heterostructure catalyst composed of NiFe layered double hydroxide nanosheets anchored on pyramidal Fe(MoO) to activate lattice oxygen for efficient and durable oxygen evolution. Our investigation reveals that oxygen vacancies within the NiFe layered double hydroxide and the internal electrical field at the material interface optimize the electronic states, allowing oxygen atoms within the crystal lattice to participate directly in the reaction. The resulting heterostructured NiFe LDH/FeMoO catalysts possess high oxygen evolution reaction activity in 1 M KOH electrolyte with a low overpotential of 316 mV at 2 A cm and maintain long-term stability over 3,000 h. Furthermore, integrating this anode into a solar-powered electrolyzer yields a high solar-to-hydrogen efficiency of 20.15%. This work provides a promising strategy for designing stable catalysts and advancing the integration of renewable energy with water electrolysis to produce clean hydrogen at scale.