Defects are critically important for metal oxides in chemical and physical applications.　　Defective TiO2-x plays vital role in harvesting of solar light for renewable energy andenvironmental remediation.A facile hydrothermal approach has been developed toprepare defective TiO2-x nanocrystals using Ti (III)-salt as a precursor and L-ascorbic acidas reductant and structure direction agent.The prepared TiO2-x nanocrystals arecomposed of a highly crystallized TiO2 core and a disordered TiO2-x outer layer,possessing high surface area，controlled Vo concentration and tunable band gap simplyvia adjusting the amount of added L-ascorbic acid.Further different morphology ofBiVO4 is prepared via a hydrothermal method using TiCl3 as structure directing agent atdifferent pH.The as-prepared BiVO4 is coupled with defective TiO2-x to form aheterojunction.The BiVO4 and defective heterojunction are prepared via a two-stephydrothermal method with unique shuriken shape morphology.The unique morphologyof BiVO4/TiO2-x heterojunction greatly enhances the surface area and suppresses theelectron/hole recombination.Defective TiO2-x completely covers the BiVO4 and thusprovides more surface area to adsorb the pollutant molecule.The incorporation of TiO2-ximproves separation of photogenerated charge carriers and visible light absorption ofBiVO4.The BiVO4/TiO2-x is prepared via a facile one-step hydrothermal method and roselike morphology are obtained.The flower like crystalline structure is greatly affected byincreasing the mole ratio of defective TiO2-x.These as-prepared defective TiO2-x，BiVO4,and BiVO4/TiO2-x heterojunctions plays a very important role in photocatalytic activities.　　The defective TiO2-x shows high photocatalytie efficiency in methylene blue and phenoldegradation as well as in hydrogen evolution under visible light，underlining thesignificance of the present strategy for structural and band gap manipulation in TiO2-based photocatalysis.Consequently，the composite heterojunction exhibits enhancedphotoeatalytic efficiency for the degradation of phenol under visible light irradiation.Theobtained BiVO4/TiO2-x achieves two folds higher photocurrent density at the potential of0.6 V with standard calomel electrode (SCE)compared to bare BiVO4.The increasedphotocatalytic activity is attributed to large surface area and rectifying electron transferacross the heterojunction.It suggest that the photo-exited electrons are effectivelytransferred from the valence band of defective TiO2-x to BiVO4，resulting in effectiveelectron-hole separation，which is responsible for high photocurrent densities and lowerphotoluminescence intensity.CO2 photoreduction with water vapor has been studied viaBiVO4/TiO2-x heterojunction system with hierarchal rose like morphology.Theproduction of CO and CH4 from CO2 are remarkably enhanced over BiVO4/TiO2-x (1∶2)that is 8 times more as compare to pure BiVO4.　　The enhanced photocatalytic activity of as-prepared defective TiO2-x，BiVO4/TiO2-xheterojunction and BiVO4/TiO2-x is related to the defects (Ti3+，oxygen vacancies)，smallcrystalline size，unique crystal morphology and large surface area.