Nanorod Array of SnO ₂ Quantum Dot Interspersed Multiphase TiO ₂ Heterojunctions with Highly Photocatalytic Water Splitting and Self-Rechargeable Battery-Like Applications

The ever-growing demand for sustainable and renewable power sources has led to the development of novel materials for photocatalytic water splitting, but enhancing the photocatalytic efficiency remains a core problem. Herein, we report a conceptual effective and experimental confirmed strategy for SnO ₂ quantum dot (QD) interspersed multiphase (rutile, anatase) TiO ₂ nanorod arrays (SnO ₂ /RA@TiO ₂ NRs) to immensely enhance the carrier separation for highly efficient water splitting by merging simultaneously the QD, multiphase, and heterojunction approaches. Under this synergistic effect, a doping ratio of 25% SnO ₂ QD interspersed into multiphase TiO ₂ NRs exhibited a superior optical adsorption and excellent photocurrent density (2.45 mA/cm ² at 1.0 V), giving rise to a largely enhanced incident light to current efficiency in the UV region (45-50%). More importantly, this material-based device can act as power supply with a voltage of ∼2.8 V after illumination, which can automatically self-recharge by reacting with oxygen vacancy and water molecule to realize reuse. The current study provides a new paradigm about heightening the carrier separation extent of QD interspersed multiphase heterojunctions, fabricating a new solar-energy-converting material/device, and achieving a highly photocatalytic water splitting/self-charging battery-like application.