Electrochemical　water　splitting　is　one　of　the　most　efficient　technologies　for　hydrogen　production　and　fabrication　of　low-cost,　robust,　and　highly　active　electrocatalysts.　It　is　attractive　because　replacing　noble　metal-based　materials　is　a　key　issue　in　current　catalysis　research.　By　using　H-2　plasma　treatment,　the　TiO2/nickel　foam　composite　is　converted　to　be　an　efficient　bifunctional　electrocatalyst　toward　both　hydrogen　evolution　reaction　(HER)　and　oxygen　evolution　reaction　(OER)　in　the　alkaline　electrolyte.　The　investigation　reveals　the　existence　of　abundant　oxygen　vacancies　of　TiO2,　which　might　lead　to　the　dramatic　improvement　of　electrical　conductivity　and　faster　charge　transfer　rate;　also,　density　functional　theory　(DFT)　calculations　suggest　that　the　oxygen　vacancies　activate　surrounding　surface　lattice　oxygen　to　induce　favorable　reactive-intermediate　adsorption　energy　of　TiO2　for　hydrogen　evolution　and　adjust　the　strength　of　the　chemical　bonds　between　the　TiO2　surface　and　reactive　intermediates　to　more　favorable　values,　inducing　a　lower　energy　barrier　for　oxygen　evolution.　The　finding　confers　a　unique　function　to　TiO2　that　is　different　from　its　widely　accepted　role　as　an　electrocatalytically　inert　semiconductor　material,　suggesting　the　H-2　plasma　treated　TiO2/nickel　foam　could　be　a　bifunctional　electrocatalyst　for　overall　water　splitting.