Tuning morphology-dependent localized surface plasmon resonance in quasi-metallic tungsten oxide nanostructures for enhanced photocatalysis

Quasi-metallic tungsten oxide (W 18 O 49 ) with unique surface plasmon resonance shows great promise for photocatalysis. In this work, the localized surface plasmon resonance (LSPR) of W 18 O 49 nanostructures is tuned through morphology control to improve the performance in photocatalytic reduction of Cr( vi ). Their morphology change from nanowires to nanobundles and urchin-like nanospheres results in a gradual blue shift and an intensity increase in their corresponding LSPR bands due to the decreased aspect ratio and the increased oxygen vacancy concentrations of the nanostructures. The three-dimensional finite element simulation demonstrates enhanced localized electric fields from nanowires to nanobundles and urchin-like nanospheres, confirming the experimental results. Benefiting from the blue-shifted and enhanced light extinction from the LSPR in the visible-NIR region, the urchin-like W 18 O 49 nanospheres show enhanced photocatalytic activity in the photoreduction of Cr( vi ) by 21.6% compared to the nanowires under visible-NIR light illumination. The mechanism leading to the enhanced photocatalytic performance is elucidated based on the unique electronic band structure of W 18 O 49 . Tunable localized surface plasmon resonance in quasi-metallic W 18 O 49 was achieved by morphology control and the urchin-like nanospheres showed blue-shifted extinction as well as enhanced photoreduction properties towards Cr( vi ).