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Noble‐Metal‐Free Photocatalytic H 2 Generation: Active and Inactive ‘Black’ TiO 2 Nanotubes and Synergistic Effects
Author(s) -
Liu Ning,
Schneider Christopher,
Freitag Detlef,
Zolnhofer Eva M.,
Meyer Karsten,
Schmuki Patrik
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201602714
Subject(s) - photocatalysis , noble metal , catalysis , materials science , cathodic protection , metal , electrochemistry , chemical engineering , nanotechnology , inorganic chemistry , chemistry , metallurgy , organic chemistry , electrode , engineering
Abstract Over the past five years a number of different synthesis approaches has been reported to obtain so‐called ‘black’ titania. One of the outstanding features of the material is that certain synthesis processes lead to the formation of an intrinsic co‐catalytic center and thus enable noble‐metal free photocatalytic H 2 ‐generation. In the present work, using TiO 2 nanotube layers, we compare three common ‘blackening’ approaches, namely i) the original high‐pressure hydrogenation (HPT‐H 2 ), ii) a classic high temperature reduction in Ar, and iii) an electrochemical (cathodic) reduction. We demonstrate that except for high pressure hydrogenation also cathodic reduction leads to an activation of TiO 2 ‐ that is, it exhibits noble‐metal‐free photocatalytic H 2 generation. Moreover, we show that a combination of cathodic reduction/high pressure hydrogenation leads to a synergistic effect, that is, a significant enhancement of the combined co‐catalytic activity.