Oxamide-modified g-C3N4 nanostructures: Tailoring surface topography for high-performance visible light photocatalysis

Abstract

Pristine graphitic carbon nitride (g-C₃N₄) suffers from poor photocatalytic activity due to its limited light adsorption, small specific surface area and feasible recombination of photogenerated charge carriers. One practical approach to solve the problem of low solar-to-hydrogen efficiency is nanostructuring the morphology of g-C₃N₄ to enhance its light-harvesting property and boost the rate of charge-carrier transportation. Here, we present a strategy to optimize the textural properties and catalytic performance of g-C₃N₄ via using oxamide (OA) as a chemical modifier in the precursor solution, which significantly make the light absorption edge shift from 440 to 650 nm. Moreover, the nanostructure of the resultant g-C₃N₄ can be easily tuned with increasing the amount of oxamide. The morphological features of g-C₃N₄ materials change from sheet-like structure to tubular structure, porous nanotube and eventually interconnected porous sheet. More interestingly, the unique g-C₃N₄ nanostructure offers advantages of a broader solar absorption spectrum and accelerates charge carrier dynamics that are favorable for advancing photocatalytic performance. The findings provide insightful information that can be used to understand the structure-property relationship in g-C₃N₄ nanostructures for improved solar-to-fuel conversion.