In this sub-project we demonstrated the use of solid state
dewetting[1,2] of thin metal films to co-catalyze TiO2
nanocavity arrays with metal co-catalyst nanoparticles for
photocatalytic H2 evolution.[3]
We focused on dewetting of noble metals such as Au[4] and Pt.[5]
We achieved full control on key experimental parameters to tune
noble metal particle size, distribution and loading on the oxide
photo-active surface. We also explored dewetting of metal
bilayers to enable dewetting-alloying effects. The latter were
used to form alloy nanoparticles, e.g. AuAg or PtNi, from which
less noble elements (Ag, Ni) were selectively removed by
dealloying, thus forming porous Au or Pt co-catalytic
nanoparticles.[6,7] Dewetting-alloying principle were also
exploited to functionalize oxide nanocavities with dewetted NiCu
nanoparticles that showed remarkable noble metal free
photocatalytic H2 evolution performances.[8,9]
We identified key anodizing and dewetting parameters to tune
the dimensions of oxide cavities and catalyst particles,
respectively. We accomplished high active metal (e.g. Pt, Au)
particle surfaces and maximized carrier transfer
from-oxide-to-particle and from-particle-to-environment,
resulting in enhanced photocatalytic reaction rates with
minimized noble metal catalyst loadings.[4,10,11] We also
demonstrated the integration of dewetted plasmonic metal (e.g.
Au) nanoparticles into photo-electrodes for solar water
splitting.[12]
Particle reactivity and economy were improved further by (i)
dewetting-alloying[8] or (ii) dealloying effects.[6,7] (i)
enabled electronic effects, such as in AuPt[13] catalytic
nanoparticles, that were proved to support faster H2 evolution
kinetics. (ii) led to porous (e.g. spongy Au, Pt, AuPt or
AuPtAg[6,7,14]) nanoparticles, with reduced noble metal content,
providing enhanced photocatalytic performances due to their high
surface area and density of surface reaction sites.
Alloying principles were used also to develop non-noble metal
catalyst particles, e.g. NiCu nanoparticles, which resulted
significantly more active than individual Ni or Cu counterparts,
and reached performances comparable to Pt catalyst
benchmarks.[8,9] Furthermore, we also achieved high activity
along with remarkable tolerance against poisoning (from alcohol
oxidation products) with dewetted Pt based alloy nanocatalysts,
e.g. PtCu systems.[15]
Some literature citations:
[1] C. V. Thompson, Annu. Rev. Mater. Res. 2012, 42, 399.
[2] F. Leroy, Ł. Borowik, F. Cheynis, Y. Almadori, S. Curiotto,
M. Trautmann, J. C. Barbe, P. Muller, Surf. Sci. Rep. 2016, 71,
391.
[3] M. Altomare, N. T. Nguyen, P. Schmuki, Chem. Sci. 2016, 7,
6865.
[4] J. E. Yoo, K. Lee, M. Altomare, E. Selli, P. Schmuki, Angew.
Chemie Int. Ed. 2013, 52, 7514.
[5] J. Yoo, M. Altomare, M. Mokhtar, A. Alshehri, S. A. Al-Thabaiti,
A. Mazare, P. Schmuki, J. Phys. Chem. C 2016, 120, 15884.
[6] N. T. Nguyen, M. Altomare, J. Yoo, P. Schmuki, Adv. Mater.
2015, 27, 3208.
[7] L. Ji, D. Spanu, N. Denisov, S. Recchia, P. Schmuki, M.
Altomare, Chem. - An Asian J. 2019, asia. 201901545.
[8] D. Spanu, S. Recchia, S. Mohajernia, O. Tomanec, S. Kment,
R. Zboril, P. Schmuki, M. Altomare, ACS Catal. 2018, 8, 5298.
[9] D. Spanu, A. Minguzzi, S. Recchia, F. Shahvardanfard, O.
Tomanec, R. Zboril, P. Schmuki, P. Ghigna, M. Altomare, ACS
Catal. 2020, 10, 8293.
[10] N. T. Nguyen, J. Yoo, M. Altomare, P. Schmuki, Chem. Commun.
2014, 50.
[11] N. T. Nguyen, M. Altomare, J. E. Yoo, N. Taccardi, P.
Schmuki, Adv. Energy Mater. 2016, 6, 1501926.
[12] M. Licklederer, R. Mohammadi, N. T. Nguyen, H. Park, S.
Hejazi, M. Halik, N. Vogel, M. Altomare, P. Schmuki, J. Phys.
Chem. C 2019, 123, 16934.
[13] H. Bian, N. T. Nguyen, J. Yoo, S. Hejazi, S. Mohajernia, J.
Muller, E. Spiecker, H. Tsuchiya, O. Tomanec, B. E. Sanabria-Arenas,
R. Zboril, Y. Y. Li, P. Schmuki, ACS Appl. Mater. Interfaces
2018, 10, 18220.
[14] N. T. Nguyen, S. Ozkan, O. Tomanec, X. Zhou, R. Zboril, P.
Schmuki, J. Mater. Chem. A 2018, 6, 13599.
[15] F. Shahvaranfard, P. Ghigna, A. Minguzzi, E. Wierzbicka, P.
Schmuki, M. Altomare, Under Consid.