Facet engineering of WO3 arrays toward highly efficient and stable photoelectrochemical hydrogen generation from natural seawater

Hydrogen generation via photoelectrochemical (PEC) technology is one of the most ideal strategies for providing sustainable fuel, in particular, from abundant natural resource (such as seawater). Herein, we demonstrate facet-controlled WO3 array decorated with reasonable distribution of dual-cocatalysts, which shows highly efficient and stable PEC H2 generation from natural seawater. The experimental and theoretical results illustrate that photo-generated electrons and holes accumulate directionally on different crystal facets of WO3 to achieve effective spatial separation, owing to the divergent energy levels of each crystal facet. Moreover, the charge utilization is further enhanced by selective modification of Ag nanoparticles and ZnFe-layered double hydroxide on different crystal facets reasonably, getting an average PEC H2 production of 38.18 μmol h−1 from natural seawater with excellent stability. This work opens up a new facet engineering pathway for the fabrication of novel photoelectrodes, which have potential applications in the fields of solar energy conversion and storage.