Optoelectronic effects differentiating absorption of right and left circularly polarized photons in thin films of chiral materials are typically prohibitively small for their direct photocurrent observation. Chiral metasurfaces increase the electronic sensitivity to circular polarization, but their out-of-plane architecture entails manufacturing and performance trade-offs. Here, we show that nanoporous thin films of chiral nanoparticles enable high sensitivity to circular polarization due to light-induced polarization-dependent ion accumulation at nanoparticle interfaces. Self-assembled multilayers of gold nanoparticles modified with l-phenylalanine generate a photocurrent under right-handed circularly polarized light as high as 2.41 times higher than under left-handed circularly polarized light. The strong plasmonic coupling between the multiple nanoparticles producing planar chiroplasmonic modes facilitates the ejection of electrons, whose entrapment at the membrane-electrolyte interface is promoted by a thick layer of enantiopure phenylalanine. Demonstrated detection of light ellipticity with equal sensitivity at all incident angles mimics phenomenological aspects of polarization vision in marine animals. The simplicity of self-assembly and sensitivity of polarization detection found in optoionic membranes opens the door to a family of miniaturized fluidic devices for chiral photonics.

No abstract

[a, b] (Photo)electrochemical processes are involved in many fields of science and technology. The use of spectroscopic techniques coupled to (photo)electrochemistry, are mandatory to get information about interfacial processes on scale ranges from millimeters to the nanoscale. The development of spectroelectrochemical cells (SECs) contributes to the progress of the field of (photo)electrochemistry and their impact in science and technology. Therefore, in this work, we describe in detail the development of a versatile SEC that can be used for conventional electrochemical experiments and several in situ techniques just by changing its window. We performed electrochemical and computational experiments to analyze the response of our SEC as a function of the working electrode size, position, and distance to the window. Besides, we show in detail how the cell can be used to perform experiments of in situ FTIR, Raman, XAFS and ultrafast spectroscopy.

The deposition of a monolayer nanoarray on the surface of a micrometer‐thick substrate is demonstrated, producing rectification characteristics at the nanoscale. The experimental results show that the heterogeneity of the structure and the charge density are the two key factors affecting rectification, which was confirmed with molecular dynamic (MD) and finite element simulations. Moreover, by altering the asymmetric electrolyte environment, the fabricated heterogeneous membrane can be used in energy conversion. This study provides insights into the mechanism underlying the generation of rectification and related factors, providing a theoretical basis for the characteristics of rectification.

In this paper, we study theoretically and experimentally the effect of induced charging currents on the fast-scan cyclic voltammetry. As explained in this paper, the phenomenon originates from the coupling between faradaic and capacitive currents in the presence of uncompensated resistance. Due to the existence of induced charging currents, the capacitive contribution to the total current is different from the capacitive current measured in the absence of electroactive species. In this paper, we show that this effect is particularly important when the ratio of the capacitive current and the total current is close to unity, even for a relatively low cell time constant. Consequently, the conventional background subtraction method may be inaccurate in these situations. In this work, we develop a method that separates the faradaic and capacitive currents, combining simulation and experimental data. The method is applicable even in the presence of potential-dependent capacitance. The theoretical results are compared with some previously reported results and with experiments carried out on the potassium ferrocyanide/ferricyanide redox couple. Platinum disk electrodes of different diameters and NaClO4 support electrolyte of different concentrations were used to obtain different cell time constants. The proposed method allowed us to separate the real capacitive current even in the situations where the conventional background subtraction used in many published papers is clearly inappropriate.

The deposition of a monolayer nanoarray on the surface of a micrometer‐thick substrate is demonstrated, producing rectification characteristics at the nanoscale. The experimental results show that the heterogeneity of the structure and the charge density are the two key factors affecting rectification, which was confirmed with molecular dynamic (MD) and finite element simulations. Moreover, by altering the asymmetric electrolyte environment, the fabricated heterogeneous membrane can be used in energy conversion. This study provides insights into the mechanism underlying the generation of rectification and related factors, providing a theoretical basis for the characteristics of rectification.

No abstract

No abstract