The covalent grafting through a rigid ester bond of a dimeric porphyrin [(H 2P) 2] and carbon nanohorns (CNHs) was accomplished. The newly formed CNH-(H 2P) 2 hybrid was found to be soluble or dispersible in several organic solvents. Application of diverse spectroscopic techniques verified the successful formation of the CNH-(H 2P) 2 hybrid material. In addition, thermogravimetric analysis revealed the amount of (H 2P) 2 loading onto CNHs, and TEM studies showed the characteristic secondary spherical superstructure morphology of the hybrid material. Efficient fluorescence quenching of (H 2P) 2 in the CNH-(H 2P) 2 hybrid suggests that photoinduced events occur from the photoexcited (H 2P) 2 to CNHs. Nanosecond transient absorption spectroscopy revealed the formation of transient species such as (H 2P) 2 •+ and CNH •- by photoinduced charge separation in CNH-(H 2P) 2. Additional proof for the photoinduced charge-separated state CNH •--(H 2P) 2 •+ was obtained, from which the electron mediates to added hexyl viologen dication (HV 2+). Finally, the CNH-(H 2P) 2 was adsorbed on nanostructured SnO 2 electrode, to construct a photoactive electrode, which reveals photocurrent and photovoltage responses with an incident photon-to-current conversion efficiency value as large as 9.6%, without the application of any bias voltage.
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