Although possessing high activity for solar hydrogen production, exploring robust Cu 2 O-based photocatalysts remains a challenging task due to its intrinsic drawback of susceptible oxidation. Herein, we present a strategy to stabilize Cu 2 O by modulating the exposed facets and structural defects of TiO 2 . Both experimental characterizations and theoretical calculations proved that surface oxygen vacancies in 101-faceted TiO 2 could create conducting channels for denoting electrons to Cu 2 O, mimicking the Z-scheme charge transfer in natural photosynthesis. Due to the defect-enhanced charge separation and the effective scavenging of oxidative holes in Cu 2 O, Cu 2 O/TiO 2 heterostructures with exposed {101} facets and oxygen vacancies exhibited 251-fold increased activity for solar water splitting, together with unpredicted photostability. In contrast, defect-induced isolated states in the bulk of 001faceted TiO 2 led to the formation of Type II Cu 2 O/TiO 2 junction with moderate photoactivity and poor stability. Thus, our work not only provides insights into the facet-and defect-dependent interfacial mechanism in heterostructured nanocatalysts but also opens up a promising avenue for developing high-performance noble-metal-free photocatalysts for energy conversion applications.

A fundamental challenge of photocatalysis is developing efficient strategies to suppress the recombination of photogenerated charge carriers. Herein, ZnO/BiVO4 hierarchical nanostructures were exemplified to demonstrate new concept of multi-electric field-assisted charge separation. The contribution of both facet engineering and defect modulation to the facilitated photocatalysis was confirmed by both experimental observations and theoretical calculations. Such integration of built-in fields in faceted BiVO4 and anisotropic ZnO nanorods, together with the possible Z-scheme at the interfaces resulted into 1.36 mmol•h -1 •g -1 O2 produced under visible light irradiation, and more than one order of magnitude enhanced apparent quantum yield at 450 nm. This work not only provides fundamental insights into the facet-dependent distribution of interfacial defects, but also offers a strategy for the design of faceted heterojunctions with controlled vacancies for significantly enhanced charge separation.

The synergetic contribution of crystal facets and atomic cocatalysts toward the photoactivity of TiO2 was fundamentally investigated. Atomic-level dispersed Pt and Au were deposited onto 001-faceted and 101-faceted TiO2, separately. When used as photocatalysts for photocatalytic H2 production, Pt/TiO2-001 showed 1156 and 3 times higher H2 evolution rate than that of cocatalyst-free TiO2-001 and Pt-cocatalyzed TiO2-101. The significantly improved photocatalytic performance was attributed to the efficient separation of high-energy electrons and the sufficient exposure of reactive sites. This study demonstrates a promising way to design single-atom-assisted photocatalysts for high-efficiency water splitting.