Evolution of the SrTiO₃–MoO₃ Interface Electronic Structure: An in Situ Photoelectron Spectroscopy Study

Abstract

Modifying the surface energetics, particularly the work function of advanced materials, is of critical importance for a wide range of surface- and interface-based devices. In this work, using in situ photoelectron spectroscopy, we investigated the evolution of electronic structure at the SrTiO3 surface during the growth of ultra-thin MoO3 layers. Because of the large work function difference between SrTiO3 and MoO3, the energy band alignment on the SrTiO3 surface is significantly modified. The charge transfer and dipole formation at the SrTiO3-MoO3 interface leads to a large modulation of work function and to apparent doping in SrTiO3. The measured evolutions of electronic structure and upward band bending suggest that the growth of ultra-thin MoO3 layers is a powerful tool with which to modulate the surface energetics of SrTiO3, and this surface engineering approach could be generalized to other functional oxides.

AgBi(WO4)2: A New Modification Material to Bi2WO6 for Enhanced and Stable Visible‐Light Photocatalyic Performance

“…The lattice parameters of pure Bi 2 WO 6 (a, b, c = 5.4617, 16.4517,5 .4543 ) and Bi 2 WO 6 (AgBi(WO 4 ) 2 -Bi 2 WO 6 )( a, b, c = 5.4584, 16.3135,5 .4519 ) are different. Such av ariation could be ascribed to the combination of Bi 2 WO 6 and AgBi(WO 4 ) 2 .T he resultsi ndicate the formation of the AgBi(WO 4 ) 2 -Bi 2 WO 6 composite. Figure 1D shows ah igh-resolution transmission electron microscopy (HRTEM) image of the AgBi(WO 4 ) 2 -Bi 2 WO 6 composite.…”

“…Figure 1D shows ah igh-resolution transmission electron microscopy (HRTEM) image of the AgBi(WO 4 ) 2 -Bi 2 WO 6 composite. The lattice fringes show that the nanocomposites are very crystalline,a nd the observed d spacing corresponds to the (211) 6 exhibits ah igher absorbance in the visible-lightr ange (400-800 nm) than pure Bi 2 WO 6 ,w hich should be due to the effect of band bending. [6] Owing to the formation of the novel AgBi(WO 4 ) 2 material, the visible-light activity changed clearly.M ethyl orange (MO), ac hemically stable azo compound with ac haracteristic absorption peak at 463 nm, was chosen as the probe molecule to assess the photocatalytic activity of the AgBi(WO 4 ) 2 -Bi 2 WO 6 photocatalyst and pure Bi 2 WO 6 under visible light (> 400 nm).…”

“…The lattice fringes show that the nanocomposites are very crystalline,a nd the observed d spacing corresponds to the (211) 6 exhibits ah igher absorbance in the visible-lightr ange (400-800 nm) than pure Bi 2 WO 6 ,w hich should be due to the effect of band bending. [6] Owing to the formation of the novel AgBi(WO 4 ) 2 material, the visible-light activity changed clearly.M ethyl orange (MO), ac hemically stable azo compound with ac haracteristic absorption peak at 463 nm, was chosen as the probe molecule to assess the photocatalytic activity of the AgBi(WO 4 ) 2 -Bi 2 WO 6 photocatalyst and pure Bi 2 WO 6 under visible light (> 400 nm). From the variation of the absorptionspectra of MO as afunction of the irradiation time in the presence of AgBi(WO 4 ) 2 -Bi 2 WO 6 (see the Supporting Information), it can be seen that the characteristic absorbance of MO at 463 nm changed little during the absorption process in the dark and diminished quicklyw ith irradiation time.…”

“…However,t he rapid recombination of the photoinduced electrons and holes is the main drawback of Bi 2 WO 6 . [5] Plasmonic photocatalysis has recently come into focus as av ery promising technology for high-performance photocatalysis.…”

“…It involves the dispersal of noble-metaln anoparticles (mostly Au and Ag) into semiconductor photocatalystsa nd results in drastic enhancement of the photoreactivity under visible light. Furthermore,s ilver ions can easily form at ungstate, thus we combined Bi 2 WO 6 with the noblem etal Ag to design at ernary system of Aurivilliuso xide semiconductors, for example, AgBi(WO 4 ) 2 .T he novel AgBi(WO 4 ) 2 material takes full advantage of Bi 2 WO 6 and Ag owing to its suitable band gap and distinctive heterostructure. AgBi(WO 4 ) 2 -Bi 2 WO 6 reveals ah igh visible-light response and highly efficient consumption of both photogenerated electrons and holes in the redox reaction.…”