Revealing high hydrogen evolution activity in zinc porphyrin sensitized hierarchical porous TiO 2 photocatalysts Spandana Gonuguntla a , Amritanjali Tiwari a,c , Sruthi Madanaboina b,c , Giribabu Lingamallu b,c,** , Ujjwal Pal a,c,* a Center for Environmental Engineering and Fossil Fuels, CSIR-Indian Institute of Chemical Technology, Hyderabad, India b Polymers and Functional Materials Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, India c Academy of Scientific and Innovative Research (AcSIR), New Delhi, India article info Article history: Received 2 March 2019 Received in revised form 16 April 2019 Accepted 27 April 2019 Available online xxx Keywords: Zn-porphyrin dye Hierarchical porous TiO 2 Photocatalysis Visible light irradiation H 2 production abstract In this work, a dye/TiO 2 system for hydrogen generation via the reduction of water has been investigated. The use of simple and template free synthesis process for hierarchical porous architecture of TiO 2 (HPT) with a panchromatic Zinc-porphyrin (LG5) sensitizer has been identified as the potential material in photoinduced hydrogen production. The effect of the dye absorbed by the Pt-HPT has been tested for the hydrogen production under visible light irradiation in presence of triethanolamine (TEOA) or Glycerol (Gly) as sacrificial electron donor (SED). The enhanced activity and effective charge transfer from the dye to the TiO 2 molecule is significant in the PHPT-LG5 composite. The PHPT-LG5 catalyst exhibited higher photocatalytic activity of 4196 mmol g 1 h 1 with an impressive turnover numbers (TON) of 8392 and apparent quantum yield (AQY) of 7.43% of light irradiation using 450 W Xe lamp when compared to the corresponding simple semiconductor as well as the N719 dye loaded catalysts. The acrylic group present in the dye molecule helps in binding the semiconductor with the dye molecule and leads to superior photocatalytic activity. The diffuse reflectance spectroscopy (DRS), and computational studies of the dye molecule and the composite suggests the better photocatalytic performance of the com- posite. The Fourier Transform Infra-Red Spectroscopy (FTIR) studies reveals the strong attachment of the dye molecule with the semiconductor hierarchical porous TiO 2 (HPT) results in the enhancement in hydrogen production, the stability tests of the photocatalyst shows higher reproducibility at neutral pH in TEOA. A systematic study of LG5 with sacrificial electron donors and pH were performed and are correlated with the photo- catalytic activity of N719 dye. The presence of the cyanoacrylic group as an anchoring group in the LG5 leads to red shift in S and Q bands suggesting the efficient intramolecular charge transfer behavior (CT) and possess strategies for broadening the light harvesting properties. The present work opens up a new window toward solar energy conversion with extended light harvesting capacity and enhanced photocatalytic activity. © 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Center for Environmental Engineering and Fossil Fuels, CSIR-Indian Institute of Chemical Technology, Hyder- abad, India. ** Corresponding author. Polymers and Functional Materials Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, India. E-mail addresses: giribabu@iict.res.in (G. Lingamallu), upal03@gmail.com (U. Pal). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (xxxx) xxx https://doi.org/10.1016/j.ijhydene.2019.04.268 0360-3199/© 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article as: Gonuguntla S et al., Revealing high hydrogen evolution activity in zinc porphyrin sensitized hierarchical porous TiO 2 photocatalysts, International Journal of Hydrogen Energy, https://doi.org/10.1016/j.ijhydene.2019.04.268