▎ 摘　　要

NOVELTY - Photocatalyst nanocomposite comprises noble metal nanoparticles, metal oxide nanoparticles, and reduced graphene oxide (rGO). The photocatalyst nanocomposite comprises rGO in an amount in the range of 40-60 wt.% total weight of the photocatalyst nanocomposite, where noble metal nanoparticles have a diameter in the range of 5-50 nm and are dispersed on the metal oxide nanoparticles which are present on the rGO. The metal oxide nanoparticles have a diameter in the range of 20-80 nm. The noble metal nanoparticles are present in an amount in the range of 2-10 mol.% based on the molar amount of the metal oxide nanoparticles. The metal oxide nanoparticles comprises a metal oxide of one metal selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb, and Mo. USE - Photocatalyst nanocomposite. ADVANTAGE - The photocatalyst nanocomposite is a more effective sunlight in the photo decomposition of organic compounds in contaminated water. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for following: (1) a method for preparing a composition comprising noble metal nanoparticles, which involves preparing an aqueous solution or suspension comprising a noble metal precursor, mixing the aqueous suspension with date seed extract to form a mixture, and heating the mixture at temperature in the range of 100-200 degrees C for 10-20 hours, preparing date seed extract by grinding date seed and heating the ground date seed in water at a temperature in the range of 60-100 degrees C for 1-5 hours, and extracting separating solids to form the date seed in the form of a liquid, and the noble metal nanoparticles have a diameter in the range of 5-30 nm; (2) a method for photodecomposing of an organic compound, which involves contacting the photocatalyst nanocomposite with an aqueous solution of an organic compound to form a mixture, and irradiating the mixture with sunlight; and (3) a method for purifying water contaminated with an organic material, which involves contacting the contaminated water with the photocatalyst nanocomposite and irradiating the mixture with sunlight.