The visible light degradation activity and the photocatalytic mechanism of tetra(4-carboxyphenyl) porphyrin sensitized TiO2

• Tetra(4-carboxyphenyl) porphyrin were chemically sensitized on TiO2.
• S2–S0 fluorescence intensity is enhanced and lifetime prolonged noticeably by TiO2.
• The TCPP-TiO2 exhibits better photoactivity under visible light than that of TiO2.
• The electronic relaxation dynamics is presented, catalytic mechanism is discussed.
• Adsorption and photo degradation of MB were systematically investigated.

Tetra(4-carboxyphenyl) porphyrin(TCPP) were chemically sensitized on TiO2 to act as visible light antenna and to modify the photoresponse properties of TiO2 particles, their properties of photo-generated holes and electrons were studied by transient absorption spectroscopes. The time-correlated single-photon counting (TCSPC) technique revealed that the S2–S0 fluorescence intensity of TCPP is enhanced noticeably by TiO2, and the lifetime prolonged. Adsorption and photo degradation of methylene blue (MB) over TCPP-TiO2 were systematically investigated. Moreover the overall picture of electronic relaxation dynamics for TCPP-TiO2 is presented, and the detailed short-time dynamics for visible-light induced catalytic mechanism was discussed. The development of the porphyrin-based photocatalyst provides an alternative approach in harnessing solar visible light and show promising prospect for the treatment of dye pollutants from wastewaters in future industrial application.

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