Synergistic photocatalysis is reported, using the optimal amounts of oxygen vacancies of high-k materials and nanoarchitecture maneuvering by employing a combinatorial sputtering approach. The highlights include (i) the successful fabrication of samples using combinatorial sputtering; (ii) a systematic investigation of the coupling effect between Y2O3-x and TiO2-x; (iii) elucidating charge carrier transport through current-voltage (I-V) and capacitance-voltage (C-V) characterizations; and (iv) providing an alternative application for high-dielectric constant (high-k) materials in photocatalysis. The simple yet effective composition spread technique rapidly determined that Sample 6 (4 at% Y2O3-x-96 at% TiO2-x, TiO2-x-rich on the Y2O3-x-TiO2-x nanorod composite composition spread) exhibited the highest photocatalytic efficiency (i.e., approximately 3.4 times and 1.4 times higher than that of P25 and pure TiO2-x nanorods, respectively). The predominant factor was determined to be electron migration along defective Y2O3-x nanorods to the sample surface. The extracted mobility was discovered to be an order of magnitude greater than that of pure TiO2-x. The photoelectrochemical stability and reusability were also demonstrated.