Gold nanoparticles have been efficiently photo-deposited onto titanate-loaded SBA-15 (Ti(x)/SBA-15) with different titania coordination. Transmission electron micros-copy shows that relatively large Au nanoparticles are photodeposited on the outer surface of the Ti(x)/SBA-15 materials and that TiO x tends to form agglomerates in close proximity to the Au nanoparticles, often forming core−shell Au/TiO x structures. This behavior resembles typical processes observed due to strong-metal support interactions. In the presence of gold, the formation of hydrogen on Ti(x)/SBA-15 during the photodeposition process and the performance in the hydroxylation of terephthalic acid is greatly enhanced. The activity of the Au/Ti(x)/SBA-15 materials is found to depend on the TiO x loading, increasing with a larger amount of initially isolated TiO 4 tetrahedra. Samples with initially clustered TiO x species show lower photocatalytic activities. When isolated zinc oxide (ZnO x) species are present on Ti(x)/SBA-15, gold nanoparticles are smaller and well dispersed within the pores. Agglomeration of TiO x species and the formation of Au/TiO x structures is negligible. The dispersion of gold and the formation of Au/TiO x in the SBA-15 matrix seem to depend on the mobility of the TiO x species. The mobility is determined by the initial degree of agglomeration of TiO x . Effective hydrogen evolution requires Au/TiO x core−shell composites as in Au/Ti(x)/SBA-15, whereas hydroxylation of terephthalic acid can also be performed with Au/ZnO x /TiO x /SBA-15 materials. However, isolated TiO x species have to be grafted onto the support prior to the zinc oxide species, providing strong evidence for the necessity of Ti−O−Si bridges for high photocatalytic activity in terephthalic acid hydroxylation. KEYWORDS: photocatalysis, titanate-loaded SBA-15, Au cocatalysts, strong metal−support interactions, advanced TEM ■ INTRODUCTION Over the past decades, highly dispersed gold nanoparticles on metal oxides have attracted interest as catalysts for several reactions like CO oxidation, selective oxidation of alcohols, or methanol synthesis. 1,2 Recently, the potential of Au nano-particles in photocatalysis has received considerable atten-tion. 3−7 Several studies have reported improved photocatalytic performance due to the visible light absorption of the Au plasmon and the electron storage capacities of Au. 3,4,8 In general, metal cocatalysts are assumed to act as an electron or hole sink enhancing the electron−hole lifetime in photo-catalysis. 3,4 One of the most studied composites in this regard are Au/TiO 2 materials which exhibit catalytic activity in organic pollutant degradation and hydrogen evolution based on photocatalytic reforming of alcohols. The utilized composites are obtained by deposition−precipitation, colloidal synthesis, or photodeposition of Au nanoparticles. 2,4,9−11 The occurrence of strong metal−support interactions (SMSIs) between oxide supports and noble metal particles upon reduction is usually characterized by H 2 or CO chemisorptions experiments. 12−15 In addition, the character-ization of metal−support interactions by advanced electron microscopy is also feasible. 14,16 In the case of TiO 2 -supported nanoparticles, it is generally accepted that a thin layer of TiO x suboxide species covers the metal nanoparticles upon reduction. 13,14,17−19 Recently, Tanaka et al. 20 observed a similar phenomenon for Pt/TiO 2 and Rh/TiO 2 composite materials prepared by photodeposition. For Au/TiO 2 materials prepared by a similar procedure, a weaker interaction between the metal and the support was proposed. However, a partial encapsula-tion was observed for all metals by XPS depth profiling. 20 Apart from the versatile materials bulk TiO 2 and Au/ TiO 2 , 17,21 single-site titania catalysts are widely studied, 22 and find particular use in photocatalytic CO 2 reduction. 23,24 Mori et al. 10,11 showed that the deposition of Au nanoparticles using photoexcited Ti-containing zeolites is feasible. We demon-strated that Au/Ti(x)/SBA composite materials prepared by