TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The auxiliary metal active component (1) is at least one of silver, lead and copper. The auxiliary metal active component (2) is at least one of potassium, sodium and calcium. The content of the main metal active component palladium is 0.01-0.8 wt.% of the total weight of the carrier. The content of the auxiliary metal active component (1) is 0.01-3 wt.% of the total weight of the carrier. The content of the auxiliary metal active component (2) is 0.01-2 wt.% of the total weight of the carrier. The carrier is at least one of aluminum oxide, titanium oxide, magnesium oxide, zinc oxide, kieselguhr, molecular sieve, kaolin and/or cordierite, or the carrier is the composite carrier formed by at least one of aluminum oxide, titanium oxide, vanadium pentoxide, silicon dioxide, zinc oxide, tin oxide, silicon carbide, kaolin and cordierite loaded on an inert substrate. The inert substrate comprises a metal substrate and a ceramic.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The free radical cleaning agent is at least one of methanol, ethanol, ethylene glycol, isopropyl alcohol and formic acid. Preferred Method: The step of reducing by exerting the ionizing radiation comprises: either using solution containing free radical scavenging agent to wet the carrier loaded with metal active component palladium precursor and the auxiliary metal active component precursor, radiating the mixture in wet state, preferably in vacuum or inert atmosphere; or adding the carrier loaded with metal active component palladium precursor and the auxiliary metal active component precursor to the solution containing free radical scavenging agent, radiating the mixture under solution soaking state; or adding the carrier to soaking liquid comprising free radical scavenging agent, metal active component palladium precursor and the auxiliary metal active component precursor, radiating the mixture under solution soaking state. The ionizing radiation source used is gamma ray, X ray or electron beam. The absorbed dose rate of the used ionizing radiation source is 10-10000 Gy/minute.