The process of two-photon-induced isomerization occurring in various organic molecules, among which azobenzene derivatives hold a prominent position, offers a wide range of functionalities, which can be used in both material and life sciences.

Plasmonic nanoparticles exhibit excellent light-harvesting properties in the visible spectral range, which makes them a convenient material for the conversion of light into useful chemical fuel. However, the need for using surface ligands to ensure colloidal stability of nanoparticles inhibits their photochemical performance due to the insulating molecular shell hindering the carrier transport. We show that cellulose fibers, abundant in chemical functional groups, can serve as a robust substrate for the immobilization of gold nanorods, thus also providing a facile way to remove the surfactant molecules. The resulting functional composite was implemented in a bioinspired photocatalytic process involving dehydrogenation of sodium formate and simultaneous photoregeneration of cofactor molecules (NADH, nicotinamide adenine dinucleotide) using visible light as an energy source. By systematic screening of experimental parameters, we compare photocatalytic and thermocatalytic properties of the composite and evaluate the role of palladium cocatalyst.

Gold nanoparticles are widely used in different fields. They are currently under extensive investigation with regard to their linear and nonlinear optical properties. So far, nanoparticles with centrosymmetrical shapes, such as nanospheres or nanorods, have received the main attention. In this work, the properties of gold nanoprisms exhibiting a highly noncentrosymmetrical threefold symmetry are investigated with hyper-Rayleigh scattering (HRS). Aqueous solutions of gold nanospheres and nanoprisms with different sizes were synthesized. The first hyperpolarizability magnitudes of both the nanospheres and nanoprisms were determined separately with the assumption of a surface origin of the nonlinearity. Using polarization-resolved HRS, retardation is shown to be largely underdeveloped for the nanoprisms as opposed to the nanospheres. The nanoprism shape noncentrosymmetry has therefore a leading role in the HRS response although it is also shown that surface defects induce deviations from the ideal threefold symmetry.