The stoichiometric water splitting using a solar-driven
Z-scheme
approach is an emerging field of interest to address the increasing
renewable energy demand and environmental concerns. So far, the reported
Z-scheme must comprise two populations of photocatalysts. In the present
work, only tungsten oxides are used to construct a robust Z-scheme
system for complete visible-driven water splitting in both neutral
and alkaline solutions, where sodium tungsten oxide bronze (Na0.56WO3–x) is used as a
H2evolution photocatalyst and two-dimensional (2D) tungsten
trioxide (WO3) nanosheets as an O2evolution
photocatalyst. This system efficiently produces H2(14
μmol h–1) and O2(6.9 μmol
h–1) at an ideal molar ratio of 2:1 in an aqueous
solution driven by light, resulting in a remarkably high apparent
quantum yield of 6.06% at 420 nm under neutral conditions. This exceptional
selective H2and O2production is due to the
preferential adsorption of iodide (I–) on Na0.56WO3–xand iodate (IO3–) on WO3, which is evidenced
by both experiments and density functional theory calculation. The
present liquid Z-scheme in the presence of efficient shuttle molecules
promises a separated H2and O2evolution by
applying a dual-bed particle suspension system, thus a safe photochemical
process.