In this work, TiO₂-based nanostructured arrays with the core-shell structure composed of the anatase NPs (ANP) on the surface of rutile nanostructures arrays are used to be photocatalysts for photoelectrochemical water splitting and CO₂ photoconversion. A superior PEC performance in alkaline electrolyte can be achieved in the hierarchical ANPs/rutile TiO₂ nanodendrite (RND) array photoanode due to the formation of type-II heterojunction of anatase/rutile TiO₂. However, the anodic-shift onset potential and decreased saturation photocurrent density are shown in the J-V curve of the ANP/RND array photoanode obtained in neutral electrolyte. An ultra-thin In₂S₃ layer is further deposited on the surface of the ANP/RND array photoanode to construct additional type-II heterojuntion for the enhancement of the charge separation of the ANP/RND array array photoanode in neutral electrolyte. By the surface modification of the photoanode with the transparent In₂S₃ layer, a photocurrent density of 1.6 mA cm⁻² at 1.23 V vs. RHE is attained using the In₂S₃/ANP/RND array photoanode in neutral electrolyte under illumination of AM 1.5G (100 mWcm⁻²). On the other hand, the rutile TiO₂ NR array (RNR) shows an ability to convert CO₂ and H₂O into CH₄, CO, and H₂ under Hg-lamp irradiation. Compared to the RNR array, ANP/RNR array shows superior photocatalytic activity for CO₂ photoconversion. Both the overall conversion efficiency and the selectivity of CH₄ production are improved as the formation of core-shell structure. The details will be discussed in this presentation.