Photoelectrocatalytic water splitting is widely recognized as one of the most promising strategies to large-scale production of hydrogen for renewable energy. To further enhance the photoelectrocatalytic efficiency, several heterostructures based on TiO₂ nanotube arrays were developed in this work. (1) TiO₂ nanotube arrays (TNTAs) were decorated with NiO nanoparticles via a sequential chemical bath deposition (CBD) approach to yield NiO@TNTA photoanodes. It demonstrated that the incident-photon-to-current-conversion efficiency (IPCE) and hydrogen production rate of the optimized NiO@TNTA reached 62.8% and 37.8 μmol.h^-1.cm^-2, respectively, approximately 5.0 times higher than pure TNTAs, which was attributed primarily to the efficient separation of photogenerated charge carriers at the p–n junction of p-type NiO and n-type TiO₂. (2) Cu_xZn_1-xIn₂S₄ ultrathin nanosheets on TiO₂ nanotube arrays (CZIS@TNTAs) was successfully synthesized by solvothermal reaction. It found that the Cu_xZn_1-xIn₂S₄ ultrathin nanosheets on TNTAs significantly enhanced visible light absorption and and a near 8.0-fold increase in photoelectrocatalytic hydrogen production rate was achieved compared to that of the blank TNTAs. The superior photoelectrocatalytic activity of CZIS@TNTAs heterostructured composite electrode was mainly due to enhanced light absorption and separation of photo-generated charges, and facilitating electron transport along the 1D TiO₂ structure. (3) TiO₂ nanotube arrays (TNTAs) sensitized by palladium quantum dots (Pd QDs) by a modified hydrothermal reaction. When Pd@TNTA nanocomposites were used as both photoanode and cathode in water splitting, the photon-to-current conversion efficiency of nearly 100% atλ=330 nm and a greatly promoted photocatalytic hydrogen production rate of 592 μmol·h⁻¹·cm⁻² under 320 mW·cm⁻² irradiation were achieved. The synergy between nanotubular structures of TiO₂ and uniformly dispersed Pd QDs on TiO₂ facilitated the charge transfer from TiO₂ nanotubes to Pd QDs and the high activity of Pd QDs catalytic center, thereby leading to high-efficiency photoelectrocatalytic hydrogen generation.