The solar-to-hydrogen conversion using the photoelectrochemical (PEC) method is a practical approach to producing clean energy. However, it relies on the availability of photocatalyst materials. In this work, a novel photocatalyst comprising molybdenum telluride quantum dots (MoTe₂ QDs)-modified titanium dioxide nanorods (TiO₂ NRs) was prepared for the enhancement of the PEC water splitting performance after combination with a Al₂O₃ layer using the atomic layer deposition (ALD) technique. MoTe₂ QDs were initially prepared, and then they were loaded onto TiO₂ NRs using a warm water bath-based heating method. After a layer of Al₂O₃ was deposited onto resulted TiO₂ NRs/MoTe₂ QDs, the composite TiO₂ NRs/MoTe₂ QDs/Al₂O₃ was finally obtained. Under simulated sunlight (100 mW·cm⁻²), such a composite exhibited a maximum photocurrent density of 2.25 mA·cm⁻² at 1.23 V (versus RHE) and an incident photon-to-electron conversion efficiency of 69.88% at 380 nm, which are 4.33 and 6.66 times those of pure TiO₂ NRs, respectively. Therefore, the composite photocatalyst fabricated in this work may have promising application in the field of PEC water splitting, solar cells and other photocatalytic devices.