Enhanced solar water splitting of an ideally doped and work function tuned {002} oriented one-dimensional WO3 with nanoscale surface charge mapping insights

[Display omitted] •Yttrium doping was employed to enhance WO3 water splitting efficiency.•Y doping yield {002} facet with decreased band gap and upward conduction band shift.•Highest photocurrent of ∼2.25 and 4.85 mA cm−2 at 1.23 V vs RHE was obtained.•Nanoscale surface charge imaging was performed to study carrier dynamics. Overcoming the limitations and understanding the surface charge characteristics of WO3 is essential for achieving efficient photoelectrochemical (PEC) water splitting. Here, we propose an ideal dopant Y to overcome the limitations and engineer WO3 properties and work function with nanoscale surface charge insights for the first time. The doping of Y in WO3 yields, {002} crystal facet oriented 1-D morphology, decrease the bandgap and work function with upward conduction band shift and improves bulk and surface charge transport/transfer properties. The 1.14 at% Y doping shows a record photocurrent of ∼2.25 and 4.85 mA cm−2 (with hole scavenger) at 1.23 V vs RHE with the increased faradaic O2 production efficiency and upward conduction band shift allowing H2 evolution with >95 % of faradaic efficiency. Importantly, nanoscale surface charge mapping was performed, revealing a decrease in work function and the improved charge dynamic insights leading to the enhanced solar water splitting efficiency.