Dye functionalized carbon nanotubes for photoelectrochemical water splitting-role of inner tubes

摘要: Dye sensitized water splitting photoelectrochemical (PEC) cells generally require the attachment of photosensitizer to a semiconductor and oxidation catalyst (WOC). Here we report for first time that dye, including zinc phthalocyanine (ZnPc), cobalt (CoPc) tris(bipyridine)ruthenium(II) (Rubpy), or functionalized pristine carbon nanotubes (dye/CNTs) without presence semiconducting oxides conventional WOCs have unusually high activity PEC in alkaline solutions under ultraviolet (UV) visible light. The activities dye/CNTs show distinctive volcano curves as function number walls with highest observed on double- triple-walled CNTs (DWNTs TWNTs). For example, photocurrent ZnPc TWNTs at 1.2 V vs. RHE is 0.32 mA cm−2, which ∼4 times 0.09 cm−2 obtained single-walled (SWNTs) one order magnitude higher than 0.02 multi-walled (MWNTs). On other hand, photocurrents are negligible CNTs, less 0.005 identical experimental conditions. This remarkable feature due unique charge separation ability dye/CNTs, where photoexcited electrons transferred inner tubes via electron tunneling dc bias voltage, significant electrocatalytic DWNTs reaction. results provide new opportunities development artificial photosynthetic systems manipulation quantum properties CNTs.