The CuO@CuFe₂O₄ core–shell structure represents a new family of photocatalysts that can be used as photoelectrodes that are able to produce hydrogen under a broad spectrum of visible light. Herein, we report a novel approach for the production of this active film by the thermal conversion of CuFe Prussian Blue Analogues. The outstanding photoelectrochemical properties of the photocathodes of CuO@CuFe₂O₄ were studied with the use of combinatory photo-electrochemical instrumental techniques which proved that the electrodes were stable over the whole water photolysis run under relatively positive potentials. Their outstanding performance was explained by the coupling of two charge transfer mechanisms occurring in core–shell architectures.

Copper(I) oxide (Cu₂O)-based photocathodes are promising materials for carbon dioxide (CO₂) reduction under visible light due to copper’s abundance and favorable energy band alignment. However, Cu₂O suffers from photocorrosion and chemical instability. Here, we present a novel approach utilizing a porous titanosilicate material (ETS-10) as a protective layer for Cu₂O, addressing these limitations. The Cu₂O was electrodeposited and coated with a thin ETS-10 layer, which prevents photocorrosion, enhances charge separation and transfer, and facilitates CO₂ capture through its highly porous structure. Comprehensive structural, compositional, and morphological analyses confirmed that ETS-10 effectively stabilized Cu₂O while maintaining its electronic properties (UV–Vis, XPS). The Cu₂O/ETS-10 photocathode exhibited a 25% enhancement in the photocurrent density at 0.0–0.1 V vs. RHE and significantly improved stability compared to bare Cu₂O. The thin ETS-10 layer acted as a passivation layer, improving charge transfer via tunneling mechanisms. This study introduces a multicomponent photocathode system, demonstrating a new application of ETS-10 in photoelectrochemical cells. The results highlight the potential of ETS-10 to enhance the efficiency and stability of photocathodes, offering a pathway for the design of advanced systems for solar-driven CO₂ reduction and artificial photosynthesis.

The constantly growing global demand for clean energy forces the development of technologiesproducing efficient and renewable energy sources. One direction of development is thin-film photovoltaicsystems that allow for the efficient conversion of solar energy to electrical or chemical energy andtheir usage in production of hydrogen, which is one of the most promising elements for storing greenenergy. The efficiency of photovoltaic systems is determined, among others factors, by properties ofa semiconductor in which light is absorbed and electron-hole pairs are generated. The efficiency ofthis process can be increased by using surface plasmon resonance induced on metallic nanoparticleslocated on the surface or inside the active material. Collective oscillations of the electron plasma excitedin the nanoparticle lead to trapping and enhancement of the electromagnetic field, which, resonantlyscattered to the active layer, increases the absorption in the cell. The selection of the material, size andshape of the nanoparticles allows spectral tuning of the absorption in the system. This study aims toimprove the efficiency of electrochemical cells with copper oxide electrodes by incorporating silvernanoparticles doped with palladium. The nanoparticles were prepared using physical vapour deposition.The fabricated structures were optically characterised by spectrophotometry and SE M microscopy.The conducted research demonstrates an increase in cell efficiency depending on the shape and sizeof the applied nanoparticles. The best results were obtained for systems subjected to post-depositionannealing, resulting in improved chemical stability and optical response of nanoparticles.Keywords: plasmonics, photoelectrochemical cells, plasmonic nanoparticles