▎ 摘　　要

NOVELTY - A photocatalyst comprises a transition metal-doped lanthanum tin pyrochlore, and graphene oxide. The transition metal includes osmium, hafnium and europium in a mass ratio of (0.2-0.3):(0.4-0.7):1. USE - The photocatalyst is used in device used for sterilizing sewage (all claimed). ADVANTAGE - The device utilizes the synergistic effect of photocatalyst and UV light, has excellent sterilization efficiency, and can directly decompose bacteria, virus and internal toxic compounds into carbon dioxide and water, and effectively inhibit photo-resurrection phenomenon. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) preparation of the photocatalyst, which involves (S1) dissolving tin(IV) chloride pentahydrate, lanthanum nitrate hexahydrate and the transition metal nitrate in ionized water, heating, adding a sodium hydroxide solution, and continuously stirring to obtain white precipitation mixtures (A) and (B), (S2) mixing the precipitation mixtures (A) and (B), adding citric acid and ethylene glycol, adjusting the pH, and heating in a water bath to form a sol, and (S3) adding graphene oxide to the sol, ultrasonically processing, vacuum drying, calcining, and grinding; (2) a sewage sterilizing device, which comprises a reactor having a liquid inlet and a liquid outlet, and a UV lamp, which is inserted into the reactor and extends along the axis of the reactor. The inner wall of the reactor is coated with a photocatalyst coating; and (3) sterilization of the sewage, which involves introducing wastewater into the reactor from the liquid inlet, sterilizing the wastewater by irradiating with the UV lamp in the reactor, coating the photocatalyst coating on the inner wall to absorb UV light to cause photocatalytic reaction to oxidize and decompose toxic compounds in the wastewater, and discharging the treated wastewater from the liquid outlet.