A full carbon-based thermoplastic photocatalyst for organic pollutants abatement: An experimental and computational study

Abstract

Remediating water pollution utilizing inorganic semiconductor photocatalysts represents the prevailing standard for sustainable depollution. However, the applicability of this method is impeded in underground environments, low Earth orbit outposts, and future lunar bases due to the scarcity of essential materials and the logistical challenges associated with supply provision. Within this framework, developing photocatalytic systems utilizing on-site accessible resources or repurposing plastic or bio-waste materials is deemed more advantageous. In particular, a hybrid fully carbon-based material incorporating a bio-derived chromophore may leverage the electronic interactions between the carbon moiety and the chromophore antenna to induce photocatalytic processes. In the present study, a porphyrin-reduced graphene oxide photocatalytic system was developed through a one-pot synthesis method, allowing the simultaneous covalent attachment of 5,10,15,20-tetrakis-(p-hydroxyphenyl)-porphyrin to the graphene oxide platform while concurrently reducing the latter. To prevent the dispersion and self-aggregation of the powder during water depollution treatments, the carbon-based photocatalyst was further integrated into polyvinyl acetate using an in-situ polymerization approach, producing various nanocomposites with different weight percentages of photocatalyst loads. The obtained products were characterized by infrared, Raman, absorption and fluorescence spectroscopies, electrochemical analysis, and thermogravimetric analysis. Photocatalytic tests, performed with both solar simulating and visible light (>400 nm), showed that the nanocomposites could act efficiently as sequestering agents and photocatalysts for organic pollutants. Finally, computational studies were performed to verify the spectroscopic features of the system and elucidate its photocatalytic mechanism. These studies demonstrated that the constructed photocatalytic system induced a planarization of the porphyrin structure, significantly enhancing its photocatalytic performance by increased light absorption, more efficient charge separation, and greater structural stability, collectively contributing to more robust and efficient catalytic cycles in the observed photocatalytic process.