Selective oxidation of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) is a promising yet challenging task, producing significant chemical feedstocks. The development of nonprecious and efficient catalytic system for biomass-derived HMF is of great importance for HMFCA production. Herein, a magnetic Ag/GO/Fe3O4/γ-Fe2O3 nanocomposite with p–n heterojunctions was fabricated using a simple refluxing method followed by an autoclave step at 120 °C. The Ag/GO/Fe3O4/γ-Fe2O3 nanocomposite is employed as a photocatalyst for the selective oxidation of HMF toward HMFCA with high conversion (99%) and selectivity (98%). The products were separated and determined using high-performance liquid chromatography-ultraviolet. The structural integrity of the synthesized photocatalyst was corroborated by Fourier-transform infrared, field emission scanning electron microscopy, energy dispersive X-ray, transmission electron microscopy, vibrating sample magnetometer, dynamic light scattering, X-ray diffraction, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, photoluminescence, and BET-BJH. Various parameters were checked, such as temperature, amount of catalyst, time, base, light sources, light intensity, recyclability, and the efficiency of the photocatalyst. In result, the highest photocatalytic efficiency (98%) was obtained using 0.03 mol % of Ag/GO/Fe3O4/γ-Fe2O3 nanocomposite under green light emitting diode light irradiation (12 W) for 1.5 h. Therefore, such a protocol provides a route to enhance the photocatalytic properties and performance of semiconductor materials for synthesizing biomass-derived value-added chemicals under environmentally friendly conditions.
