The aim of this study is to find optimal Ar plasma etching conditions without significantly altering the surface of PtFe bimetallic nanoparticles (BNPs). Various treatment parameters such as acceleration voltage, ion beam current, and etching time are considered in this study. Studies have shown that severe alteration of surface chemical composition is closely related to the energy of Ar ions. High energy (3 keV) Ar cleaning, leads to partial reduction of alloy particles along with decontamination. However, the use of ion energies of 1 keV or lower leads to preferential cleaning with minor alteration of surface chemistry and subsequently allows us to acquire reliable XPS data of PtFe BNPs. Profiling of the NPs revealed that both metal oxides and elemental metals are simultaneously synthesized during dry plasma reduction. PtO is formed at the level of 30 atomic percent in the synthesis procedure, which is due to the influence of oxygen radicals in atmospheric plasma.