A novel magnetic HS−-adsorptive nanocomposite photocatalyst (rGO/CoMn2O4–MgFe2O4) for hydrogen fuel production using H2S feed

Abstract

Synthesis of low-cost, eco-friendly, semiconducting solar-energy materials with excellent photocatalytic activity [high surface area, good reactant adsorption, photon harnessing in the visible region, and low charge recombination] for application in pollutant conversion to hydrogen is of great importance from environmental remediation as well as green energy and fuel production perspectives. In the present work, a magnetic heterojunction of CoMn₂O₄/MgFe₂O₄ and reduced graphene oxide (rGO) was synthesized through a combined Hummers’/hydrothermal method. The obtained nanocomposite (rGO/CoMn₂O₄–MgFe₂O₄) was employed for photocatalytic conversion of H₂S feed into hydrogen fuel. Adsorption studies in the feed solution proved a good capability for the photocatalyst to adsorb HS⁻ reactant from the reaction medium. This effect was ascribed to the presence of the CoMn₂O₄ component, serving as a strong bisulfide adsorbent. VSM (vibrating sample magnetometry) analysis revealed that the magnetic property of the photocatalyst was due to the MgFe₂O₄ component. Photocatalytic investigations showed that the addition of rGO to the CoMn₂O₄/MgFe₂O₄ nanocomposite not only improves its reactant adsorption capacity, but also increases the photocatalyst surface area, enhances photon absorption, and suppresses the charge (e/h) recombination, which eventually boosts the photocatalyst activity to produce more hydrogen fuel (∼1.5 times).