▎ 摘　　要

NOVELTY - A multilayered composite thin film material comprises substrate having positively-charged surface, 1st bilayer material having layer of metal nanocrystal particles (10) having negatively charged surface, are chosen from ruthenium (Ru), rhodium (Rh), osmium (Os), iridium (Ir), palladium (Pd), gold (Au), silver (Ag) and platinum (Pt), and are attached to substrate surface by charge attraction, and coating layer of graphene quantum dots, each graphene quantum dot having positively charged surface and attached to layer of metal nanocrystal particles by charge attraction; and 1-49 additional bilayers containing layer of metal nanocrystal particles having negatively charged surface, are chosen from Ru, Rh, Os, Ir, Pd, Au, Ag and Pt, and are attached to preceding layer of graphene quantum dots by charge attraction and coating layer of graphene quantum dots, each graphene quantum dot having positively charged surface and attached to layer of metal nanocrystal particles by charge attraction. USE - A multilayered composite thin film for catalyzing organic reaction and device for photodetection and/or harvesting energy (all claimed). ADVANTAGE - Thin film has versatile and high efficient catalytic performance including selective reduction of aromatic nitro compounds in water and electrocatalytic oxidation of methanol at ambient conditions. Catalytic and electrocatalytic performances of multilayer films can be easily tuned by assembly cycle and type of metal nanocrystals. Agglomeration of metal nanocrystals is prevented, and exposure of more active sites on surface is allowed. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) assembling multilayered composite thin film material which involves providing substrate having positively charged surface; dipping substrate into 1st solution containing negatively charged metal nanocrystals (10), subsequently washing and drying dipped material to form negatively charged surface of metal nanocrystals; dipping product into 2nd solution containing positively charged graphene oxide quantum dots (20), subsequently washing and drying dipped material to form positively charged surface; optionally repeating steps using the product as substrate; and subjecting product to annealing step under heat and inert atmosphere where metal nanocrystals used in each step are chosen from Ru, Rh, Os, Ir, Pd, Au, Ag and Pt; (2) catalyzing organic reaction which involves contacting greater than or equal to 1 reagents for organic reaction with composite material and providing conditions necessary to effect the organic reaction; and (3) energy harvesting which involves providing light-transparent device containing working electrode that consists of composite material, greater than or equal to 1 other electrode as counter electrode and electrolyte, irradiating device with light to generate photocurrent, and converting water to hydrogen and oxygen. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the assembly of multilayer composite thin films as active catalysts for selective aromatic nitro compound reduction and electrochemical methanol oxidation under ambient conditions. Negatively charged metal nanocrystals (10) Positively charged graphene oxide quantum dots (20) Assembly buildup (30)