In this work, we investigate the optical properties of triangular gold nanoprisms synthesized following a one-pot chemical process and using triethylene glycol (TREG) and polyvinylpyrrolidone (PVP) as solvent and capping agents. The nanoprisms sustain a strong localized surface plasmon resonance (LSPR) which is exploited in surface-enhanced Raman scattering (SERS) by the PVP and TREG molecules present at the nanoparticle surface. The work is focused on the temporal fluctuations of the SERS signal. The assignment of the observed Raman features is based on density functional theory calculations, performed for various interaction states between the PVP or the TREG molecules and the gold surface, in a simple model system. The SERS blinking is analyzed quantitatively using the autocorrelation of spectrally selected temporal SERS traces. We also use SERS covariance maps in order to investigate the cross-correlation between the relevant Raman features. We show that the fluctuations of the PVP and TREG SERS signals are not random. We found that the Raman features associated with the CO stretching vibrations are fingerprints of the interaction between the organic molecules and the nanoparticle surface. In particular, we observe quasi-periodic adsorption/desorption events of the PVP molecules that reveal their dynamical interaction with the gold surface. From the SERS covariance maps, we also point out correlations between the TREG and PVP signals which we interpret as occasional exchange of the two molecular species. The dependence of the SERS blinking on the detuning between the Raman excitation and the surface plasmon resonance is also investigated. We show that the optical excitation plays an important role in the photoinduced chemical processes that occur close to the nanoparticle surface.

We report on the facile and low-temperature one-pot chemical synthesis of lightly doped Zn Cu O and hybrid Au-Zn Cu O photocatalysts with low Cu molar content (0< x < 0.7%) using 1,3-propanediol polyol simultaneously as solvent, reducing and a stabilizing agent, without any final thermal treatment. The photocatalysts have been characterized by X-ray diffraction, N adsorption study, UV-vis diffuse reflectance spectroscopy, inductively coupled plasma optical emission spectroscopy, and transmission electron microscopy. The lightly doped hybrid Au-Zn Cu O photocatalysts consisted in faceted quasi-spherical large-size Au nanoparticle cores surrounded by closely packed small-size Zn Cu O nanoparticles. Taking the photocatalytic degradation of Diuron under solar light as liquid-phase test reaction, the lightly doped Au-Zn Cu O hybrid photocatalysts with optimized x = 0.09% Cu content showed strongly enhanced photocatalytic activity when compared to the bare ZnO counterpart. The observed 16-fold higher degradation rate constant resulted jointly from the light doping of ZnO with Cu to form Zn Cu O photocatalyst and further from the addition of gold nanoparticles allowing interfacial oxide-to-metal electron transfer within the hybrid Au-Zn Cu O photocatalyst.

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