We propose a novel idea to improve the surface properties of carbon-based Pt-free electrocatalysts in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and Alkaline Fuel Cells (AFCs).

We report a direct photoelectrochemical response from low cost carbon dots (CDs) prepared from chitosan via a solvothermal method. The carbon dots were covalently linked to an indium tin oxide (ITO) surface through a self-assembled silane monolayer. We attribute the photocurrent of the ITO–silane–CD surface to a photogenerated electron-transfer process by CDs under illumination with a wavelength of 420 nm to 450 nm. The self-assembled monolayer of CDs was used for ac-photocurrent imaging of the surface with micron scale lateral resolution. This discovery opens up new applications for CDs as biocompatible, light-addressable electrochemical sensors in bioanalytical and bioimaging applications.

We investigate the effect of the nature of the substrate and the bottom interface on the out-of-plane polarization orientation of ultrathin (10-nm) lead zirconate titanate (PZT) thin films of (001) orientation by photoelectron spectroscopy of samples without surface contamination. The substrate nature is varied between insulator (strontium titanate, STO) and semiconductor ($\mathrm{Nb}$-doped STO, STON) and finally to a metal with a work function lower than that of PZT (strontium ruthenate, SRO). Outward polarization is obtained for PZT/STON(001) and inward polarization is obtained for PZT/STO(001) and PZT/SRO(001). Explanations are given for all these typical cases, the main elements being charge accumulation for compensation of the depolarization field, self-doping of PZT films, and the interface electric field driving the orientation of the polarization of the ferroelectric films. We find p-type self-doping is correlated with the inward polarization, and the driving field is formed between a negatively charged region with negatively ionized acceptors near the interface with the substrate and the p-type degenerate region with holes accumulated inside, toward the surface. This mechanism may be reversed under the assumption of n-type self-doping, positively ionized donors near the interface, and accumulated electrons toward the surface in the case of an interface with a substrate with a higher work function, being in line with recent data (PZT/$\mathrm{Pt}$ or $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_3/\mathrm{SRO}$).

Subjecting copper to short anodic pulses during the electrocatalytic reduction of carbon dioxide (CO₂RR) has been shown to improve the activity and selectivity towards hydrocarbons and alcohols. Nonetheless, the nature of the active sites is still unclear. Here the evolution of the morphology, chemical state and crystal structure of Cu(100) exposed to potential pulses during the CO₂RR was resolved by a combination of spectroscopy, microscopy and diffraction methods applied concurrently. Under anodic potential pulses, (n10) facets were formed. Moreover, alternating anodic to cathodic potential pulses during the CO₂RR also lead to the stabilization of copper oxide species located either at the surface or directly underneath ultrathin metallic copper layers, depending on the specific pulse potential treatment applied. Both findings are key for the enhanced ethylene and ethanol production reported during pulsed CO₂RR.