MoP/g-C3N4 QDs/TiO2 Nanotubes electrode for enhanced photoelectrochemical water oxidation

Abstract

Developing efficient and stable photoelectrocatalysts for water oxidation is critical for sustainable energy conversion. In this work, a ternary heterostructure composed of TiO₂ nanotubes (TNTs), graphitic carbon nitride quantum dots (g-C₃N₄ QDs), and molybdenum phosphide (MoP) was synthesized via electrochemical anodization and sequential loading strategies. The optimized TiO₂ nanotubes (3 h anodization) exhibited uniform morphology and enhanced crystallinity, serving as an ideal substrate for further modification. The introduction of g-C₃N₄ QDs extended the light absorption range to visible regions, while MoP acted as an effective co-catalyst to accelerate charge transfer and suppress electron–hole recombination. The synergistic effects among the three components significantly improved photoelectrochemical performance, achieving a photocurrent density of 1.18 μA/cm² at 1.23 V vs. RHE, which was 3.1 times higher than pristine TiO₂. This work provides a rational design strategy for high-performance photoelectrodes and advances their applications in solar-driven water splitting.