Photo Upscaling of Formic Acid to H2 and C(sp2)-N Cross-Coupling via K+ Intercalated Carbon Nitride: A New Sustainable Horizon Towards Fuel and High-end Pharmaceutics

Solar propelled liquid organic hydrogen (H2) bearer - formic acid (FA) dehydrogenation is one of the promising pathway for green H2 production. In this regard, we have shown potassium intercalated (K+) carbon nitride (KPCN) as photocatalyst to unleash a new route, photo-valorization of FA to H2 in synergism with photo-redox cross-coupling of FA as C1 source with o-phenylenediamine (PDA) to produce benzimidazole (BA). It was realized that Pt/1KPCN produces 94 µmol.h-1.g-1 of H2 which was 23-folds higher compared to bare Pt/CN along with 50 % conversion of PDA to produce pharmaceutically important BA with AQY of 0.93 % at λ = 400 nm. Besides, charge transfer kinetics of Pt/1KPCN after K+ incorporation was ascertained by PL, photocurrent and solid-state EPR studies. Further the plausible mechanistic insights including basicity were thoroughly probed by scavenger-controlled experiments and CO2 TPD analysis, respectively. Apparently, Pt/1KPCN has shown the potential further to reduce in situ generated CO2 molecules (via dehydrogenation) to CO molecules. Thus, the current work provides a new milder sustainable protocol to expedite FA as renewable source not only to produce syngas, a solar fuel precursor for the Fischer-Tropsch synthesis (FTS) but also to nurture the carbon circular economy by producing high-end pharmaceutics.