Sugarcane bagasse-derived hydrochar for enhanced graphitic carbon nitride photocatalysis in Rhodamine B degradation...

A central challenge in graphitic carbon nitride (CN) photocatalysis is to overcome its inherent limitations, such as rapid charge recombination and poor visible-light absorption, which hinder catalytic activity enhancement. To address these issues, hydrochar (HC) derived from sugarcane bagasse, an agricultural solid waste, was employed to construct a composite photocatalyst (HC/CN) with CN via ball-milling method. The incorporation of HC introduced abundant O-containing functional groups and facilitated the formation of electron transfer channels within the composite. These structural modifications significantly enhanced the visible-light absorption, narrowed the bandgap, and improved the separation and transfer efficiency of photogenerated charge carriers. Consequently, the HC/CN composite exhibited remarkably superior photocatalytic performance for the degradation of Rhodamine B under visible light, achieving 99.99% removal within 50 min, whereas pristine CN and ball-milled CN (MCN) required 150 min and 120 min, respectively. The reaction rate constant of HC/CN was 9.14 and 4.92 times higher than those of pristine CN and MCN, respectively, and 32 times higher than that of pristine HC. Mechanistic studies revealed that superoxide radicals play the dominant role during the photodegradation of RhB over HC/CN. This work not only presents an efficient strategy for enhancing CN photocatalysis by constructing electron transfer channels, but also highlights a sustainable pathway for the valorization of agricultural waste into functional materials for environmental remediation.