Unraveling Interband Hot‐Electron Transfer in Hydrogenated Au@Cu2O/TiO2 Heterostructure Nanocrystals for Enhanced Hydrogen Evolution

Why It Matters

The breakthrough demonstrates a viable route to harness near‑infrared sunlight for scalable photocatalytic hydrogen production, addressing a key efficiency bottleneck in solar‑fuel technologies.

Key Takeaways

• LSPR-driven hot electrons transfer from Au core to Cu2O shell
• Z‑scheme TiO2/Cu2O suppresses recombination, boosts charge separation
• Achieves 9.3 mmol g⁻¹ h⁻¹ H₂, 3.9× faster than control
• AQY reaches 2.5% at 650 nm, 0.8% at 800 nm
• Oxygen vacancies improve carrier mobility and long-term stability

Pulse Analysis

The quest for solar‑driven hydrogen hinges on expanding light absorption beyond the visible spectrum. Conventional photocatalysts, typically based on TiO₂, suffer from wide band gaps that limit utilization of the abundant near‑infrared (NIR) portion of sunlight. Plasmonic metals such as gold introduce localized surface plasmon resonance (LSPR), which can generate hot carriers capable of bridging this gap. By integrating an Au core within a Cu₂O shell, the new heterostructure leverages interband hot‑electron transfer, converting NIR photons into chemically useful charge carriers.

Beyond plasmonic excitation, the engineered Au@Cu₂O/TiO₂ system employs a Z‑scheme configuration that aligns the conduction band of TiO₂ with the valence band of Cu₂O. This arrangement promotes spatial separation of electrons and holes, dramatically reducing recombination losses. Simultaneously, intentional oxygen vacancies within the Cu₂O lattice act as shallow donors, enhancing carrier mobility and stabilizing the photocatalyst under prolonged illumination. The combined effect yields a hydrogen evolution rate of 9.3 mmol g⁻¹ h⁻¹—nearly four times higher than the Au‑free counterpart—while maintaining robust activity across 650‑800 nm wavelengths.

The implications for the renewable energy sector are significant. Extending photocatalytic activity into the NIR window unlocks a larger fraction of the solar spectrum, potentially lowering the cost per kilogram of green hydrogen. Moreover, the modular nature of the core‑shell design suggests scalability: similar strategies could be applied to other plasmonic metals or semiconductor shells to tailor band alignments for diverse redox reactions. Future research will likely focus on optimizing vacancy concentrations, integrating co‑catalysts, and transitioning from laboratory powders to structured reactors, paving the way for commercially viable solar‑fuel platforms.