@article {44215, title = {Pt - g-C3N4 - (Au/TiO2): electronically integrated nanocomposite for solar hydrogen generation}, journal = {International Journal of Hydrogen Energy}, volume = {43}, year = {2018}, month = {JAN}, pages = {601-613}, type = {Article}, abstract = {

A potential nanocomposite photocatalyst was designed by integrating Pt nanoclusters (co catalyst and electron sink) with graphitic carbon nitride (g-C3N4 (gcn)) (charge diffusion) and 0.5 wt \% Au containing Au-TiO2 (AuT) (plasmonic on semiconductor) for solar water splitting (SWS). Variety of Pt-gcn-AuTiO2 compositions has been evaluated for SWS under one sun conditions. Complexity of the photocatalyst was increased systematically from Au-TiO2, gcn-TiO2 to Pt-gcn-Au-TiO2 to explore the influence of different combinations. Electronic integration of charge separation/diffusion component (gcn) with light absorbing sensitizer components (Au and gcn), and co-catalyst (Pt) seems to be the critical factor to improve hydrogen yield (HY) or overall efficiency. Although addition of gcn increase the HY of composites, there is no SWS activity observed on bare TiO2 or gcn. Au or Pt on gcn enhances the charge separation effectively and interface between Au and/or Pt with gcn works as the Schottky barrier. A monodispersion of Au over TiO2 and Pt nanoclusters over gcn/AuTiO2 composite lead to the maximum solar hydrogen yield (1.52 mmol/h g) with an apparent quantum yield (AQY) of 7.5\%. Photoelectron and photoluminescence spectral studies confirm the electron transfer from Au to gcn, and Au and/or gcn to titania. A thorough physico-chemical investigation of various composites underscores the electronic integration aspects of the nanocomposite towards storage of electrons in the Pt co-catalyst and hence an effective charge separation and an increase in AQY. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

}, keywords = {Electronic integration, Photocatalysis, Schottky barrier, Solar hydrogen, water splitting}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2017.11.057}, author = {Devaraji, Perumal and Gopinath, Chinnakonda S.} } @article {46792, title = {Can half-a-monolayer of pt simulate activity like that of bulk pt? solar hydrogen activity demonstration with quasi-artificial leaf device}, journal = {ACS Applied Materials \& Interfaces}, volume = {12}, year = {2020}, month = {JUL }, pages = {30420-30430}, type = {Article}, abstract = {

Pt is the best cocatalyst for hydrogen production. It is also well-known that the surface atomic layer is critical for catalysis. To minimize the Pt content as cocatalyst, herein we report on half-a-monolayer of Pt (0.5 theta(Pt)) decorated on earth-abundant Ni-Cu cocatalyst, which is integrated with a quasiartificial leaf (QuAL) device (TiO2/ZnS/CdS) and demonstrated for efficient solar hydrogen production. For the QuAL, TiO2 is sensitized with ZnS and CdS quantum dots by the SILAR method. The 0.5 theta(Pt)-decorated Ni-Cu shows an onset potential of 0.05 V vs reversible hydrogen electrode for the hydrogen evolution reaction, which is almost similar to that of commercial Pt/C. Photoactivity of the present QuAL device with either bulk Pt or 0.5 theta(Pt)-coated Ni-Cu cocatalyst is, surprisingly, equal. Our findings underscore that a fraction of a monolayer of Pt can enhance the activity of the cocatalyst, and it is worth exploring further for the high activity associated with atomic Pt and other noble metals.

}, keywords = {artificial leaf, nickel-copper, Photocatalysis, platinum, Solar hydrogen}, issn = {1944-8244}, doi = {10.1021/acsami.0c07431}, author = {Bajpai, Himanshu and Patra, Kshirodra Kumar and Ranjan, Ravi and Nalajala, Naresh and Reddy, Kasala Prabhakar and Gopinath, Chinnakonda S.} } @article {47589, title = {Electronically integrated mesoporous Ag-TiO2 nanocomposite thin films for efficient solar hydrogen production in direct sunlight}, journal = {Energy Technology}, volume = {10}, year = {2021}, month = {AUG}, pages = {2100356}, type = {Article}, abstract = {

The synthesis of mesoporous TiO2 by a solution-based assembly process and Ag/TiO2 nanocomposites is provided. The efficacy of Ag/TiO2 nanocomposite as photocatalyst in thin-film form is demonstrated for solar hydrogen generation in sunlight. Integration of Ag with TiO2 dramatically enhanced the H-2 production: with 1 wt\% Ag on TiO2 (TiAg-1), the H-2 yield was observed to be 4.59 mmol h(-1) g(-1), which is 2.3 (30) times larger than 0.5 wt\% Ag on TiO2. TiAg-1 shows 4.3 times higher activity in film form compared with its powder counterpart. High photocatalytic efficiency is attributed to the surface plasmon resonance effect of Ag, electronic integration of Ag with TiO2, and subsequent valence band broadening, large distribution of Ag nanoparticles and abundant Ag-TiO2 Schottky junctions, and the later minimizes electron-hole recombination. Interparticle mesoporous network increases necking and the high surface area offers easy accessibility of the reactants to a large number of active sites.

}, keywords = {heterogeneous catalysis, heterojunctions, plasmon effect, Silver, solar energy conversion, Solar hydrogen}, issn = {2194-4288}, doi = {10.1002/ente.202100356}, author = {Mani, Sunesh S. and Rajendran, Sivaraj and Nalajala, Naresh and Mathew, Thomas and Gopinath, Chinnakonda S.} }