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Enhanced Photocatalytic Reduction of CO 2 to CO through TiO 2 Passivation of InP in Ionic Liquids
Author(s) -
Zeng Guangtong,
Qiu Jing,
Hou Bingya,
Shi Haotian,
Lin Yongjing,
Hettick Mark,
Javey Ali,
Cronin Stephen B.
Publication year - 2015
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.201501671
Subject(s) - passivation , ionic liquid , photocatalysis , reduction (mathematics) , materials science , ionic bonding , inorganic chemistry , chemical engineering , chemistry , catalysis , nanotechnology , ion , layer (electronics) , organic chemistry , engineering , geometry , mathematics
A robust and reliable method for improving the photocatalytic performance of InP, which is one of the best known materials for solar photoconversion (i.e., solar cells). In this article, we report substantial improvements (up to 18×) in the photocatalytic yields for CO 2 reduction to CO through the surface passivation of InP with TiO 2 deposited by atomic layer deposition (ALD). Here, the main mechanisms of enhancement are the introduction of catalytically active sites and the formation of a pn ‐junction. Photoelectrochemical reactions were carried out in a nonaqueous solution consisting of ionic liquid, 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM]BF 4 ), dissolved in acetonitrile, which enables CO 2 reduction with a Faradaic efficiency of 99 % at an underpotential of +0.78 V. While the photocatalytic yield increases with the addition of the TiO 2 layer, a corresponding drop in the photoluminescence intensity indicates the presence of catalytically active sites, which cause an increase in the electron‐hole pair recombination rate. NMR spectra show that the [EMIM] + ions in solution form an intermediate complex with CO 2 − , thus lowering the energy barrier of this reaction.