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Title: Noble metal free photocatalytic H 2 generation on black TiO 2: On the influence of crystal facets vs. crystal damage

In this study, we investigate noble metal free photocatalytic water splitting on natural anatase single crystal facets and on wafer slices of the [001] plane before and after these surfaces have been modified by high pressure hydrogenation and hydrogen ion-implantation. Here, we find that on the natural, intact low index planes, photocatalytic H 2 evolution (in the absence of a noble metal co-catalyst) can only be achieved when the hydrogenation treatment is accompanied by the introduction of crystal damage, such as simple scratching and miscut in the crystal, or by implantation damage. X-ray reflectivity, Raman, and optical reflection measurements show that plain hydrogenation leads to a ≈ 1 nm thick black titania surface layer without activity, while a colorless, density modified, and ≈7 nm thick layer with broken crystal symmetry is present on the ion implanted surface. These results demonstrate that (i) the H-treatment of an intact anatase surface needs to be combined with defect formation for catalytic activation and (ii) activation does not necessarily coincide with the presence of black color.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Univ. of Erlangen-Nuremberg, Erlangen (Germany). Inst. for Surface Science and Corrosion (LKO), Dept. of Materials Science WW-4
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL), Materials Science Division
  3. Univ. of Erlangen-Nuremberg, Erlangen (Germany). Inst. for Surface Science and Corrosion (LKO), Dept. of Materials Sciences 6
  4. Univ. of Erlangen-Nuremberg, Erlangen (Germany). Inst. for Surface Science and Corrosion (LKO), Dept. of Materials Science WW-4; Univ. of Erlangen-Nuremberg, Erlangen (Germany). Inst. of Biomaterials
  5. Univ. of Erlangen-Nuremberg, Erlangen (Germany). Inst. for Surface Science and Corrosion (LKO), Dept. of Materials Science WW-4; King Abdulaziz Univ., Jeddah (Saudi Arabia). Dept. of Chemistry
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 110; Journal Issue: 7; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ion implantation; Electron densities of states; Crystal defects; Single crystals; High pressure
OSTI Identifier:
1353174