Green hydrogen production through photocatalytic seawater splitting on MS2/TiO2 (M=Ni/Co/Sn) nanocomposites over simulated solar irradiation
Sivagowri Shanmugaratnam, Punniamoorthy Ravirajan, Yohi Shivatharsiny, Dhayalan Velauthapillai
Abstract
Green hydrogen will play an important role in reducing carbon emission in sectors like transportation, power supply, and industry. However, for it to become competitive technology, the costs related to hydrogen production must be reduced. Photocatalytic hydrogen production is one of the green hydrogen production methods that have the potential to become cost effective. So far, photocatalytic water splitting has mainly focused on hydrogen production from pure water systems, but it is practically attractive to study methods for seawater systems, which will make better use of available natural resources. In this study, we focus on the synthesis and characterization of a variety of metal dichalcogenide-embedded titanium dioxide (NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2 ) nanocomposite materials as photocatalysts for seawater splitting. The materials were synthesized using a facile hydrothermal method and were used for simulated seawater, seawater and deionized water splitting with 4 h of simulated solar illumination. The amounts of 48.11, 24.94, 15.04, and 2.78 mmolg −1 hydrogen were successfully produced with NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2, and pristine TiO 2 nanomaterials, respectively. Highest amount of H 2 with NiS 2 /TiO 2 photocatalyst can be attributed to the low bandgap of NiS 2, which acts as a co-catalyst. Our study clearly demonstrates that low-cost, noble-metal-free nanocomposite photocatalysts could be promising candidates for realizing efficient solar-to-hydrogen conversion from seawater splitting. • -NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2 - nanocomposite materials were synthesized for photocatalytic water splitting in seawater, simulated seawater and deionized water using a facile hydrothermal method. • 48.11, 24.94, and 15.04 mmol/g of hydrogen were obtained with NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2 nanomaterials in seawater. • Highest photocatalytic activity with metal chalcogenide-embedded titanium dioxide can be attributed to the low bandgap of metal chalcogenide material, which acts as a co-catalyst. • This study clearly demonstrates that low-cost, noble-metal-free nanocomposite photocatalysts could be promising candidates for realizing efficient solar-to-hydrogen conversion from seawater splitting.