TY - JOUR

T1 - Light-Triggered Boost of Activity of Catalytic Bola-Type Surfactants by a Plasmonic Metal–Support Interaction Effect

AU - Sutter, Sebastian

AU - Trepka, Bastian

AU - Siroky, Stephan

AU - Hagedorn, Kay

AU - Theiß, Sebastian

AU - Baum, Peter

AU - Polarz, Sebastian

N1 - Funding Information: The current research was funded by an ERC consolidator grant (I-SURF; project 614606). SFB-1214 is acknowledged for providing analytical methods in the particle analysis center (PAC, project Z1).

PY - 2019/5/16

Y1 - 2019/5/16

N2 - The maximization of activity is a general aim in catalysis research. The possibility for light-triggered enhancement of a catalytic process, even if the process is not photochemical in nature, represents an intriguing concept. Here, we present a novel system for the exploration of the latter idea. A surfactant with a catalytically active head group, a protonated polyoxometalate (POM) cluster, is attached to the surface of a gold nanoparticle (Au NP) using thiol coupling chemistry. The distance of the catalytically active center to the gold surface could be adjusted precisely using surfactants containing hydrocarbon chains (C n ) of different lengths (n = 4-10). Radiation with VIS-light has no effect on the catalytic activity of micellar aggregates of the surfactant. The situation changes, as soon as the surfactants have been attached to the Au NPs. The catalytic activity could almost be doubled. It was proven that the effect is caused by coupling the surface plasmon resonance of the Au NPs with the properties of the POM head group. The improvement of activity could only be observed if the excitation wavelength matches the absorption band of the used Au NPs. Furthermore, the shorter the distance between the POM group and the surface of the NP, the stronger is the effect. This phenomenon was explained by lowering the activation energy of the transition state relevant to the catalytic process by the strong electric fields in the vicinity of the surfaces of plasmonic nanoparticles. Because the catalytic enhancement is wavelength-selective, one can imagine the creation of complex systems in the future, a system of differently sized NPs, each responsible for a different catalytic step and activated by light of different colors.

AB - The maximization of activity is a general aim in catalysis research. The possibility for light-triggered enhancement of a catalytic process, even if the process is not photochemical in nature, represents an intriguing concept. Here, we present a novel system for the exploration of the latter idea. A surfactant with a catalytically active head group, a protonated polyoxometalate (POM) cluster, is attached to the surface of a gold nanoparticle (Au NP) using thiol coupling chemistry. The distance of the catalytically active center to the gold surface could be adjusted precisely using surfactants containing hydrocarbon chains (C n ) of different lengths (n = 4-10). Radiation with VIS-light has no effect on the catalytic activity of micellar aggregates of the surfactant. The situation changes, as soon as the surfactants have been attached to the Au NPs. The catalytic activity could almost be doubled. It was proven that the effect is caused by coupling the surface plasmon resonance of the Au NPs with the properties of the POM head group. The improvement of activity could only be observed if the excitation wavelength matches the absorption band of the used Au NPs. Furthermore, the shorter the distance between the POM group and the surface of the NP, the stronger is the effect. This phenomenon was explained by lowering the activation energy of the transition state relevant to the catalytic process by the strong electric fields in the vicinity of the surfaces of plasmonic nanoparticles. Because the catalytic enhancement is wavelength-selective, one can imagine the creation of complex systems in the future, a system of differently sized NPs, each responsible for a different catalytic step and activated by light of different colors.

KW - nanoparticle capping agents

KW - photocatalysis

KW - polyoxometalates

KW - self-assembly

KW - surfactants

UR - http://www.scopus.com/inward/record.url?scp=85065074106&partnerID=8YFLogxK

U2 - 10.1021/acsami.9b03727

DO - 10.1021/acsami.9b03727

M3 - Article

C2 - 30950261

VL - 11

SP - 15936

EP - 15944

JO - ACS Applied Materials & Interfaces

JF - ACS Applied Materials & Interfaces

SN - 1944-8244

IS - 17

ER -