A Direct Z‐Scheme Van Der Waals Heterojunction (WO 3 ·H 2 O/g‐C 3 N 4 ) for High Efficient Overall Water Splitting under Visible‐Light

Achieving overall water splitting is crucial for the effective application of recycling solar energy. Here, we design and construct a direct Z‐scheme van der Waals heterojunction composed by ultrathin WO 3 ·H 2 O and g‐C 3 N 4 nanosheets to achieve efficient overall water splitting without adding any sacrificial agents. This WO 3 ·H 2 O/g‐C 3 N 4 system can efficiently transport the electrons, which leading to a considerable improvement in the photocatalytic performance. Due to the suitable band edge potentials for H 2 , O 2 evolution, and remarkable charge transfer, the direct WO 3 ·H 2 O/g‐C 3 N 4 Z‐scheme system exhibits prominent photocatalytic activity for both H 2 and O 2 production under visible‐light illumination, the H 2 , O 2 production rate up to 482 and 232 µmol g −1  h −1 respectively, which is greatly higher than the H 2 evolution of g‐C 3 N 4 nanosheets (109 µmol h −1  g −1 ) and the O 2 evolution of WO 3 ·H 2 O nanosheets (57   µmol h −1  g −1 ) under the same condition. The measured quantum efficiency of the WO 3 ·H 2 O/g‐C 3 N 4 heterojunction reaches 6.2% at 420 nm.