Biomass Lignin Integrated Polymeric Carbon Nitride for Boosted Photocatalytic Hydrogen and Oxygen Evolution Reactions.

The carbon nitride (CN) has good stability, a comprehensive band structure, and a more straightforward fabrication process that makes them a top candidate for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). So far, scientists have been involved broadly in utilizing smaller carbon-based molecules to modify the CN framework for better-quality solar to fuel energy conversion. Still, the modification of material with a natural macromolecule has been explored insufficiently. In this regard, we firstly a copolymerized carbon nitride (CNP x) by conjugating a novel monomer 2,6-dibenzolumazine with CN through molecular integration (CNP x). The copolymerized catalysts demonstrated noteworthy improvement in photocatalytic activities as compared to pristine CN. Following this, we further combine our superior sample (CNP 5.0) with the underlying biomass-based lignin molecules forming CNP-L x. The biomass-modified CNP-L x obtained through this process has an increased HER and OER under visible light (λ=420 nm). Findings demonstrate the catalytic performance seven times higher for CNP-L x and three times enhanced for CNP x sample than CN catalyst. These improvements can be attributed to the ultrathin nanostructure and efficient visible light absorption of the CN, well-balanced exciton states of the organic monomer, and the synergetic effect of lignin synergetic effect on its surface. Lignin-activated CNP 5.0 photocatalysts produced through this method can prove cost-effective and efficient alternatives for solar overall water splitting. A proposed graphical scheme on conduction band (CB) and valence band (VB) utilizing lignin modified copolymerized CNP for overall water splitting under visible light illumination. [Display omitted] [ABSTRACT FROM AUTHOR]