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Direct photocatalytic hydrogen evolution from water splitting using nanostructures of hydrate organic small molecule as photocatalysts

Li, Huihui, Jie, Liulun, Pan, Jiannan, Kang, Longtian, Yao, Jiannian
Journal of materials chemistry A 2016 v.4 no.17 pp. 6577-6584
electron transfer, energy transfer, hydrogen production, nanoparticles, nanosheets, pH, paraquat, photocatalysis, photocatalysts, photosensitizing agents, platinum, zinc
Organic small molecules with a suitable energy level have usually been considered as photosensitizers rather than catalysts for photocatalytic hydrogen evolution (PHE). Herein, we achieved direct PHE using hydrate zinc tetraphenylporphyrin (ZnP, ZnTPP·H₂O) nanostructures synthesized by a liquid-phase chemical reaction as photocatalysts. The shape-dependent photocatalysis revealed that the ZnP nanosheets (ZnP-NS) exhibit higher PHE activity (∼0.16 mmol g⁻¹ h⁻¹) than the ZnP octahedron nanoparticles (ZnP-NPs) (∼0.06 mmol g⁻¹ h⁻¹). After in situ construction of the rubrene/ZnP-NS heterostructure, more efficient PHE of this pure organic nanostructure was obtained due to the occurrence of photoinduced electron transfer and Förster resonance energy transfer (FRET). The optimal PHE rate is ∼0.56 mmol g⁻¹ h⁻¹. Furthermore, with the addition of 3.0 mM methyl viologen (MV) and 3.8 wt% platinum, a PHE rate of ∼9.3 mmol g⁻¹ h⁻¹ can be achieved at pH = 7. This study offers a new route to design organic small molecules as photocatalysts.