Synergistic Effects of CdTe Quantum Dots and Nb ₂ O ₅ Nanostructures for Enhanced Photocatalytic Hydrogen Generation

The quest for efficient materials for solar energy conversion into hydrogen has driven the development of novel photoanodes for photoelectrochemical applications. In this study, Nb2O5 photoanodes were produced via anodization, and the formation potential, optical, and structural properties were systematically investigated. The optimal performance was achieved at 40 V, resulting in a well-defined nanochannel morphology and the formation of an orthorhombic crystalline phase. CdTe quantum dots (QDs) were electrochemically synthesized, exhibiting a zinc-blende crystal structure and an average size of 3.94 nm. These QDs were incorporated into the nanoporous Nb2O5 matrix through a ligand-assisted sensitization process, ensuring homogeneous distribution throughout the structure, as confirmed by SEM, HRTEM, and XPS. The sensitization time had a significant impact on device performance, with 30 min identified as the optimal duration based on PEC measurements. The introduction of CdTe QDs enhanced the photocurrent density from 0.08 to 0.53 mA cm–2, and markedly reduced the electron transfer resistance, thereby improving the overall photoelectrochemical efficiency. During hydrogen evolution experiments, QD leaching was initially observed. However, this issue was effectively mitigated by removing MPA ligands via heat treatment in an argon atmosphere, which enabled the retention of 80% of the initial photocurrent after 12 h under 1.23 V vs RHE. The H2 production rate reached 145 μL cm–2 h–1, representing a 2.5-fold increase compared to unsensitized Nb2O5 photoanodes. This study presents, for the first time, the formation of a Nb2O5/CdTe heterojunction for photoelectrocatalytic applications. The results demonstrate that this strategy is a highly effective approach to enhancing the photoactivity of Nb2O5, making it a promising candidate for sustainable hydrogen production.