Orthogonal hydrogen and halogen bonding facilitate intermolecular charge transfer between barbaturic acid and molecular halogens over g-C3N4 nanosheet: A comparative experimental and DFT calculations

Abstract

Durable photogenerated Charge separation in nanomaterials is an essential parameter in semiconductors application. Here, we immobilized the orthogonal hydrogen bonding (HB) and halogen bonding (XB) stabilized complexes of barbaturic acid with molecular halogens (X2=I2, Br2, Cl2, and F2) on g-C3N4 surface for the decreasing the photogenerated electron/hole recombination process. The BUX2/g-C3N4 composite reveal lower band gap (2.65 eV) than the pristine g-C3N4. Spectroscopic techniques such as UV–Vis, photoluminescence, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and energy dispersive X-ray fluorescence (EDXRF) were used to investigate the molecular complexes and BUX2/g-C3N4 composites. Density Functional Theory calculations (rwb97xd/lanl2dz) were used to investigate the molecular interactions and explore the binding noncovalent forces. The cooperative orthogonal HB and XB stabilized the BUX2 complexes in polar solvents. Noncovalent forces (vdW) were the dominant factors for the binding of BUX2 on g-C3N4 nanosheets. The quantative charge transfer from g-C3N4 to BUX2 increases in the order of I2 > Br2 > Cl2 > F2, which in accordance with the complexes stability.