Facile Synthesis of Zn/Fe@C Photocatalyst for Visible-Light-Driven H₂O₂ Production and Pollutant Degradation

A zinc oxide-iron oxide embedded graphitic carbon (Zn/Fe@C) photocatalyst was successfully synthesized by pyrolysis of chitosan hydrogel impregnated with zinc and iron salts. Structural characterization confirmed the formation of a predominantly crystalline, multi-phase oxide system, while morphological analysis revealed a rough and heterogeneous surface with aggregated features. Elemental analysis further verified the incorporation of Zn and Fe species within the graphitic carbon matrix. The photocatalytic performance of the prepared material was evaluated through hydrogen peroxide (H₂O₂) production and dye degradation under simulated solar irradiation. Zn/Fe@C exhibited superior H₂O₂ production performance, achieving a maximum concentration of 2.9 mmol L^-1. The use of different alcohols as sacrificial agents revealed that 2-propanol significantly enhanced H₂O₂ generation, while increasing catalyst loading improved H₂O₂ production due to the availability of additional active sites. In dye degradation experiments, the photocatalyst demonstrated high efficiency toward the removal of representative organic dyes, including methylene blue, methyl orange, and acridine orange, with the latter showing the highest degradation efficiency of 96.6%. The effect of catalyst loading indicated that lower dosages resulted in optimal performance, which was attributed to improved light penetration and reduced aggregation effects. Control experiments confirmed that photocatalysis was the dominant mechanism over adsorption. Furthermore, increasing the metal precursor concentration enhanced photocatalytic activity, while the material maintained good reusability over multiple cycles. Furthermore, Zn/Fe@C was compared with Cu/Fe@C and Cu/Zne@C where Zn/Fe@C exhibited superior performance among the investigated photocatalysts in H₂O₂ production and dye degradation. Overall, the results highlight the potential of the developed Zn/Fe@C photocatalyst as a promising material for sustainable H₂O₂ production and efficient degradation of organic pollutants.