Semiconductor-Metal Composites: The Role of Ion Migration and Alloy Formation on the Stability of Core Shell Cocatalysts for Photoinduced Water Splitting

TY - JOUR

T1 - Semiconductor-Metal Composites

T2 - The Role of Ion Migration and Alloy Formation on the Stability of Core Shell Cocatalysts for Photoinduced Water Splitting

AU - Hondow, Nicole S.

AU - Chou, Yi-Hsin

AU - Sader, Kasim

AU - Brydson, Rik

AU - Douthwaite, Richard E.

PY - 2010/12/30

Y1 - 2010/12/30

N2 - Semiconductor-metal nanoparticle composites can mediate the photoinduced reaction of water to H-2 and O-2. High spatial resolution microscopic analysis was used to investigate the structure and composition of nominally NiO/Ni core shell nanoparticles supported on the semiconductors NiTa2O6 and InTaO4, respectively. For NiTa2O6 the metal nanoparticles were confirmed as NiO/Ni core shell structures and photoreaction demonstrated that H-2 and O-2 were evolved from water at 2.75 and 1.00 mu mol g(-1) h(-1), respectively, under ca. 1 W/cm(-2) using an unfiltered 300W Xe lamp. Analysis of the composite after reaction showed evidence of degradation of the NiO/Ni nanoparticles to Ni(OH)(2). For InTaO4 bulk modification of the core shell nanoparticles occurred via diffusion of indium ions from the InTaO4 semiconductor to the nanoparticles to give a new core shell structure best formulated as Ni1.25In0.75O3/Ni3In. Although all other analytical data (PXRD, DRUVS, BET, SEM) is essentially identical to that reported for NiO/Ni:InTaO4, the activity of Ni1.25In0.75O3/Ni3In:InTaO4 for the photoinduced water splitting reaction was significantly less, exhibiting no activity with wavelengths >400 nm and only H-2 under unfiltered illumination. In contrast to NiO/Ni, degradation of Ni1.25In0.75O3/Ni3In core shell nanoparticles was not observed. The data indicate that ion diffusion between the semiconductor and nanoparticle are likely to partly explain why obtaining reproducible photoreactions using these complex systems is often difficult to achieve and that ion diffusion can be detrimental to photoactivity.

AB - Semiconductor-metal nanoparticle composites can mediate the photoinduced reaction of water to H-2 and O-2. High spatial resolution microscopic analysis was used to investigate the structure and composition of nominally NiO/Ni core shell nanoparticles supported on the semiconductors NiTa2O6 and InTaO4, respectively. For NiTa2O6 the metal nanoparticles were confirmed as NiO/Ni core shell structures and photoreaction demonstrated that H-2 and O-2 were evolved from water at 2.75 and 1.00 mu mol g(-1) h(-1), respectively, under ca. 1 W/cm(-2) using an unfiltered 300W Xe lamp. Analysis of the composite after reaction showed evidence of degradation of the NiO/Ni nanoparticles to Ni(OH)(2). For InTaO4 bulk modification of the core shell nanoparticles occurred via diffusion of indium ions from the InTaO4 semiconductor to the nanoparticles to give a new core shell structure best formulated as Ni1.25In0.75O3/Ni3In. Although all other analytical data (PXRD, DRUVS, BET, SEM) is essentially identical to that reported for NiO/Ni:InTaO4, the activity of Ni1.25In0.75O3/Ni3In:InTaO4 for the photoinduced water splitting reaction was significantly less, exhibiting no activity with wavelengths >400 nm and only H-2 under unfiltered illumination. In contrast to NiO/Ni, degradation of Ni1.25In0.75O3/Ni3In core shell nanoparticles was not observed. The data indicate that ion diffusion between the semiconductor and nanoparticle are likely to partly explain why obtaining reproducible photoreactions using these complex systems is often difficult to achieve and that ion diffusion can be detrimental to photoactivity.

KW - VISIBLE-LIGHT IRRADIATION

KW - PHOTOCATALYTIC DECOMPOSITION

KW - HYDROGEN EVOLUTION

KW - CRYSTAL-STRUCTURE

KW - CATALYSTS

KW - O-2

KW - H-2

KW - NANOSHEETS

KW - OXYNITRIDE

KW - NB

UR - http://www.scopus.com/inward/record.url?scp=78650615998&partnerID=8YFLogxK

U2 - 10.1021/jp108974s

DO - 10.1021/jp108974s

M3 - Article

SN - 1932-7447

VL - 114

SP - 22758

EP - 22762

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

IS - 51

ER -