Electrochemical Impedance Investigation of Dye-Sensitized Solar Cells Based on Electrospun TiO2 Nanofibers Photoanodes

Mesoporous Surface-Sulfurized Fe-Co3O4 Nanosheets Integrated with N/S Co-Doped Graphene as a Robust Bifunctional Electrocatalyst for Oxygen Evolution and Reduction Reactions

Playing a significant role in electrochemical energy conversion and storage systems, heteroatom-doped transition metal oxides are key materials for oxygen-involving reactions. Herein, mesoporous surface-sulfurized Fe-Co₃O₄ nanosheets integrated with N/S co-doped graphene (Fe-Co₃O₄-S/NSG) were designed as composite bifunctional electrocatalysts for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). Compared with the Co₃O₄-S/NSG catalyst, it exhibited superior activity in the alkaline electrolytes by delivering an OER overpotential of 289 mV at 10 mA cm^-2 and an ORR half-wave potential of 0.77 V vs. RHE. Additionally, Fe-Co₃O₄-S/NSG kept stable at 4.2 mA cm^-2 for 12 h without significant attenuation to render robust durability. This work not only demonstrates the satisfactory effect of the transition-metal cationic modification represented by iron doping on the electrocatalytic performance of Co₃O₄, but it also provides a new insight on the design of OER/ORR bifunctional electrocatalysts for efficient energy conversion.

Mechanical and Corrosion Behavior of Zr-Doped High-Entropy Alloy from CoCrFeMoNi System

The aim of the paper is to study the Zr addition effect on the mechanical properties and corrosion behavior of a high-entropy alloy from the CoCrFeMoNi system. This alloy was designed to be used for components in the geothermal industry that are exposed to high temperature and corrosion. Two alloys, one Zr-free (named Sample 1) and another one doped with 0.71 wt.% Zr (named Sample 2), were obtained in a vacuum arc remelting equipment from high-purity granular raw materials. Microstructural characterization and quantitative analysis by SEM and EDS were performed. The Young modulus values for the experimental alloys were calculated on the basis of a three-point bending test. Corrosion behavior was estimated by linear polarization test and by electrochemical impedance spectroscopy. The addition of Zr resulted in a decrease in the value of the Young modulus but also in a decrease in corrosion resistance. The beneficial effect of Zr on the microstructure was the grain refinement, and this ensured a good deoxidation of the alloy.

Boosting the Photoelectrochemical Water Oxidation Performance of TiO2 Nanotubes by Surface Modification Using Silver Phosphate

Photoelectrocatalytic approaches are fascinating options for long-lasting energy storage through the transformation of solar energy into electrical energy or hydrogen fuel. Herein, we report a facile method of fabricating a composite electrode of well-aligned TiO2 nanotubes (TNTs) decorated with photodeposited silver phosphate (Ag3PO4) nanoparticles. Assessment of the optical, physiochemical and photoelectrochemical features demonstrated that the fabricated TNTs/Ag3PO4 films showed a substantially boosted photocurrent response of 0.74 mA/cm2, almost a 3-fold enrichment in comparison with the pure TNTs. Specifically, the applied bias photon-to-current efficiency of the fabricated TNTs/Ag3PO4 composite electrode was 2.4-fold superior to that of the pure TNTs electrode. In these TNTs/Ag3PO4 photoanodes, the introduction of Ag3PO4 over TNTs enhanced light absorption and improved charge transfer and surface conductivity. The developed process can be generally applied to designing and developing efficient contact interfaces between photoanodes and numerous cocatalysts.