Surface composition of samples and oxidation states of elements were determined by XPS, and the data obtained are summarized in Table 1. Titanium, oxygen, carbon, silver, and copper were analyzed in detail, and a fraction of the oxidation states of elements from the deconvolution of XPS peaks is shown in Table 2. Exemplary XPS peaks for Ti , O 1s, C 1s, Cu , and Ag of DAP/Cu/Ag sample are shown in Fig. 6. The ratio of oxygen to titanium exceeded two, reaching ca. 7.6 and 3.4 to 7.2 for bare and modified DAP samples, respectively. Enrichment of the titania surface with oxygen has been often reported, e.g., a ratio of 4.6 for titania samples prepared by the microemulsion method,41 a ratio of 2.5 for titania prepared by laser ablation,85 and a ratio of 2.2 to 5 for OAP prepared by HT (depending on duration of HT).65 Significant excess of oxygen on the surface of DAP (7.6 ratio) is reasonable since anatase particles are formed under the continuous flow of oxygen. The deconvoluted oxygen peak indicates the presence of three forms of oxygen at ca. 529.4, 531.6, and 533.1 eV. The first peak is related to oxygen in the crystal lattice of , the second peak to , and OH groups bound with two titanium atoms, and the third one is related mainly to hydroxyl groups bound to titanium and carbon (, ).86,87 The content of lattice oxygen on the surface of DAP amounted to only ca. 20%, thus the surface was mainly composed of hydroxyl groups (or other compounds containing oxygen, e.g., carbon dioxide from air). Modification of the DAP surface with NPs of noble metals resulted in a decrease in the content of hydroxyl groups (except for codeposited sample: DAP/Ag-Cu), which is reasonable since surface modifiers displaced other adsorbed species. This competition of adsorption on the titania surface between hydroxyl groups and metal deposits can be crucial for photocatalytic performance, especially in the case of reactions performed in organic media. For example, for cyclohexane oxidation, deposition of gold NPs on the titania surface resulted in a decrease in the amount of available hydroxyl groups, which in consequence decreased the amount of generated hydroxyl radicals during irradiation and thus the efficiency of oxidation.88 Slightly smaller content of lattice oxygen () in codeposited sample (DAP/Ag-Cu) indicates that some particular bimetallic nanostructure with surface oxygen enrichment was formed. Deconvolution of Cu and Ag peaks confirms that this sample differed significantly from others, having the largest Cu content, the smallest Ag content, the smallest content of , the largest content of Cu(0), and the largest content of . The most surprising aspect of the codeposited material is that it contains the largest fraction of Cu and the smallest fraction of Ag of any of the bimetallic composites: it is expected that the materials prepared by sequential deposition, DAP/Cu/Ag, and DAP/Ag/Cu, should have larger Ag and Cu content, respectively. Interestingly, the DAP/Ag-Cu sample has an even larger content of Cu on the surface (14 wt. %) than single-modified DAP with Cu (DAP/Cu, 12.9 wt. %). It is thought that during codeposition, segregation of two metals could result in the formation of a silver core and Cu discontinuous shell (fine Cu clusters deposited on the surface of silver). Similar metal segregation for Ag-Cu composites has already been reported, e.g., during radiolytic reduction–deposition of Ag and Cu on titania P25.81 However, based on obtained STEM-EDS images, it is difficult to confirm/reject the possibility of formation of an Ag(core)-Cu(shell) due to the small sizes of metallic clusters (nanosized) uniformly dispersed on the support (Fig. 5). It is highly possible that the mixture of Ag-Cu alloyed nanoclusters, core–shell nanoclusters, and monometallic nanoclusters/NPs (nanoclusters of Cu and large deposits of Ag) could coexist in the codeposited sample.