The　surface　reaction　kinetics　of　perovskite　oxides　is　usually　regulated　by　the　formation　of　carriers　in　the　crystal　lattice　by　element　doping,　but　there　are　few　studies　on　improving　the　surface　exchange　coefficient　by　adjusting　the　microstructure.　In　this　work,　a　significant　increase　in　the　titanate　surface　exchange　coefficient　was　achieved　by　in　situ　growth　of　active　nickel　nanoparticles　at　grain　boundaries　by　controlling　the　nonstoichiometry　of　the　oxide　material.　Chemically　customized　titanates　lead　to　a　significant　improvement　in　electrochemical　performance.　A　current　density　of　1.28　A　cm−2　was　obtained　by　direct　electrolysis　of　carbon　dioxide　at　1.8　V　and　800　°C.　The　concepts　exemplified　here　can　be　used　to　design　and　develop　more　complex　oxide　materials　with　advanced　capabilities　across　a　range　of　possible　application　areas.　©　2022　The　Royal　Society　of　Chemistry.