Quenching-Induced Structural Distortion of Graphitic Carbon Nitride Nanostructures: Enhanced Photocatalytic Activity and Electrochemical Hydrogen Production.

ABSTRACT: Engineered nanomaterials are emerging in the field of environmental chemistry. This study involves the analysis of the structural, electronic, crystallinity, and morphological changes in graphitic carbon nitride (g-C₃N₄), an engineered nanomaterial, under rapid cooling conditions. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Brunauer-Emmett-Teller, Fourier transform infrared, Raman, band gap, and Mott-Schottky analyses strongly proved that the liquid N₂-quenched sample of g-C₃N₄ has structural distortion. The photocatalytic efficiency of engineered g-C₃N₄ nanostructures was analyzed through the degradation of reactive red 120 (RR120), methylene blue (MB), rhodamine B, and bromophenol as a representative dye. The photocatalytic dye degradation efficiency was analyzed by UV-vis spectroscopy and total organic carbon (TOC) analysis. The photocatalytic efficiency of g-C₃N₄ under different quenching conditions included quenching at room temperature in ice and liquid N₂. The degradation efficiencies are found to be 4.2, 14.7, and 82.33% for room-temperature, ice, and liquid N₂ conditions, respectively. The pseudo-first-order reaction rate of N₂-quenched g-C₃N₄ is 9 times greater than the ice-quenched g-C₃N₄. Further, the TOC analysis showed that 55% (MB) and 59% (RR120) of photocatalytic mineralization were achieved within a time duration of 120 min by the liquid N₂-quenched g-C₃N₄ nanostructure. In addition, the quenched g-C₃N₄ electrocatalytic behavior was examined via the hydrogen (H₂) evolution reaction in acidic medium. The liquid N₂-quenched g-C₃N₄ catalyst showed a lower overpotential with high H₂ evolution when compared with the other two g-C₃N₄-quenched samples. The results obtained provide an insight and extend the scope for the application of engineered g-C₃N₄ nanostructures in the degradation of organic pollutants as well as for H₂ evolution.

SUBMITTER: Durairaj A 

PROVIDER: S-EPMC6648192 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature