Ammonia photosynthesis under ambient conditions using an efficient nanostructured FeS2/CNT solar-energy-material with water feedstock and nitrogen gas

Abstract

Through a facile solvothermal route, pyrite (FeS2) semiconductor nanoparticles were synthesized in the absence and presence of carbon nanotube (CNT), and employed as effective, narrow-bandgap, hole-scavenger-free, photocatalyst/solar-energy materials in a water photosplitting setup, to convert N2 molecules into ammonia – a modern/green H-based fuel and agriculturally important chemical. The investigations revealed that the presence of CNT substantially enhances the photocatalyst activity. The superiority of FeS2/CNT nanocomposite energy material was explained in detail in terms of the ability of CNT to increase the photocatalyst surface area and interact with more N2 molecules, boost the absorption of photons and effectually harvest the incident light, retard the recombination of e/h pairs, decrease the system impedance and facilitate the charge transfer process. Based on water-oxidation and proton reduction phenomena occurring upon the photocatalyst surface, the N2-photofixation process was also interpreted from mechanistic/photoelectrochemical/energetic perspective.