Evidence for Metal–Support Interactions in Au Modified TiO_<i>x</i>/SBA-15 Materials Prepared by Photodeposition

Gold nanoparticles have been efficiently photodeposited onto titanate-loaded SBA-15 (Ti­(<i>x</i>)/SBA-15) with different titania coordination. Transmission electron microscopy shows that relatively large Au nanoparticles are photodeposited on the outer surface of the Ti­(<i>x</i>)/SBA-15 materials and that TiO_<i>x</i> tends to form agglomerates in close proximity to the Au nanoparticles, often forming core–shell Au/TiO_<i>x</i> structures. This behavior resembles typical processes observed due to strong-metal support interactions. In the presence of gold, the formation of hydrogen on Ti­(<i>x</i>)/SBA-15 during the photodeposition process and the performance in the hydroxylation of terephthalic acid is greatly enhanced. The activity of the Au/Ti­(<i>x</i>)/SBA-15 materials is found to depend on the TiO_<i>x</i> loading, increasing with a larger amount of initially isolated TiO₄ tetrahedra. Samples with initially clustered TiO_<i>x</i> species show lower photocatalytic activities. When isolated zinc oxide (ZnO_<i>x</i>) species are present on Ti­(<i>x</i>)/SBA-15, gold nanoparticles are smaller and well dispersed within the pores. Agglomeration of TiO_<i>x</i> species and the formation of Au/TiO_<i>x</i> structures is negligible. The dispersion of gold and the formation of Au/TiO_<i>x</i> in the SBA-15 matrix seem to depend on the mobility of the TiO_<i>x</i> species. The mobility is determined by the initial degree of agglomeration of TiO_<i>x</i>. Effective hydrogen evolution requires Au/TiO_<i>x</i> core–shell composites as in Au/Ti­(<i>x</i>)/SBA-15, whereas hydroxylation of terephthalic acid can also be performed with Au/ZnO_<i>x</i>/TiO_<i>x</i>/SBA-15 materials. However, isolated TiO_<i>x</i> 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

Phase Selection Enabled Formation of Abrupt Axial Heterojunctions in Branched Oxide Nanowires

Rational synthesis of nanowires via the vapor–liquid–solid (VLS) mechanism with compositional and structural controls is vitally important for fabricating functional nanodevices from bottom up. Here, we show that branched indium tin oxide nanowires can be in situ seeded in vapor transport growth using tailored Au–Cu alloys as catalyst. Furthermore, we demonstrate that VLS synthesis gives unprecedented freedom to navigate the ternary In–Sn–O phase diagram, and a rare and bulk-unstable cubic phase can be selectively stabilized in nanowires. The stabilized cubic fluorite phase possesses an unusual almost equimolar concentration of In and Sn, forming a defect-free epitaxial interface with the conventional bixbyite phase of tin-doped indium oxide that is the most employed transparent conducting oxide. This rational methodology of selecting phases and making abrupt axial heterojunctions in nanowires presents advantages over the conventional synthesis routes, promising novel composition-modulated nanomaterials

A Polar Corundum Oxide Displaying Weak Ferromagnetism at Room Temperature

Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO₃ (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO₃ has a weak ferromagnetic ground state below 356 Kthis is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO₃

A Polar Corundum Oxide Displaying Weak Ferromagnetism at Room Temperature

Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO₃ (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO₃ has a weak ferromagnetic ground state below 356 Kthis is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO₃

A Polar Corundum Oxide Displaying Weak Ferromagnetism at Room Temperature

Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO₃ (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO₃ has a weak ferromagnetic ground state below 356 Kthis is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO₃