Research News

Researchers develop new hydrogen-generating photocatalyst design

New Delhi, Jun 15 (By Jyoti Singh): Researchers from the Indian Institute of Technology (IIT) Mandi, in collaboration with researchers from Yogi Vemana University, have designed a novel photocatalyst that can remove pollutants from water while simultaneously generating hydrogen using sunlight. The researchers have designed a series of novel and multifunctional nanocomposite photocatalysts by coupling mesocrystals of calcium titanate with edge sulphur atoms enriched molybdenum disulphide and reduced graphene oxide. A specific and useful example of a photocatalytic reaction is the splitting of water into hydrogen and oxygen. Although this reaction was demonstrated as early as 1972 by Fujishima and Honda, the inefficiency of the process has been a bottleneck in scaling up the technology for practical applications. In addition, the researchers have also used these photocatalysts in the degradation of organic pollutants found in water. Dr Venkata Krishnan associate professor, School of Basic Sciences, IIT Mandi (in the middle) along with his research scholars Ajay Kumar (Left) Ashish Kumar (Right) “The performance of a photocatalytic reaction depends upon the efficiency with which the photocatalyst converts light energy into photogenerated charges that drives the reaction of interest,” explains Dr Venkata Krishnan, Associate Professor, School of Basic Sciences, IIT Mandi. Photocatalysts work by generating electron-hole pairs when exposed to light of specific wavelengths, which induces the reaction they are meant to catalyze.  Oxide materials such as titania and titanates are commonly studied photocatalysts, but these materials are often inefficient by themselves because the electrons and holes combine before the reaction can be propelled forward. “Mesocrystals, a new class of ‘superstructures’ made of highly ordered nanoparticles, could limit the recombination of electron-hole pairs because the free electrons that are generated flow between particles before they can recombine with the hole,” says Dr. Venkata Krishnan. “Our combination showed a 33-fold enhanced photocatalytic hydrogen evolution over pure calcium titanate, with apparent light-to-electron conversion efficiencies of 5.4%, 3.0% and 17.7% for light of three different wavelengths, orange light (600 nm wavelength) producing the highest efficiency”, says Dr. Venkata Krishnan. The mesocrystal-semiconductor-graphene combination also degrades many kinds of organic pollutants when exposed to light, which makes…