Visible-Near-Infrared-Light-Driven Oxygen Evolution Reaction with Noble-Metal-Free WO 2 -WO 3 Hybrid Nanorods.

Understanding and manipulating the one half-reaction of photoinduced hole-oxidation to oxygen are of fundamental importance to design and develop an efficient water-splitting process. To date, extensive studies on oxygen evolution from water splitting have focused on visible-light harvesting. However, capturing low-energy photons for oxygen evolution, such as near-infrared (NIR) light, is challenging and not well-understood. This report presents new insights into photocatalytic water oxidation using visible and NIR light. WO ₂ -WO ₃ hybrid nanorods were in situ fabricated using a wet-chemistry route. The presence of metallic WO ₂ strengthens light absorption and promotes the charge-carrier separation of WO ₃ . The efficiency of the oxygen evolution reaction over noble-metal-free WO ₂ -WO ₃ hybrids was found to be significantly promoted. More importantly, NIR light (≥700 nm) can be effectively trapped to cause the photocatalytic water oxidation reaction. The oxygen evolution rates are even up to around 220 (λ = 700 nm) and 200 (λ = 800 nm) mmol g ^-1 h ^-1 . These results demonstrate that the WO ₂ -WO ₃ material is highly active for water oxidation with low-energy photons and opens new opportunities for multichannel solar energy conversion.