In this work, well-defined Ni-based alloys, labeled M1 (Ni0.8CoO0.1Zn0.05MnO0.02Ti0.01Y0.01Al0.01) and M2 (NiO0.8CoO0.1Zn0.05MnO0.02Ti0.01Y0.01Al0.01), were prepared by ball-milling technique and used as electrodes for the generation of hydrogen. Electrochemical Impedance Spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) were employed in order to understand the surface state and proton adsorption phenomena during cathodic polarization. It was found that high concentration species such as NiO and/or Ni(OH)2 induces passivation effect, suppressing the HER by increasing the electrode resistance. The charge transfer, double layer capacitance and adsorption of protons toward the electrode interface ware found to be highly controlled by the intrinsic nature of the alloy in turn.

BACKGROUND: Environmental pollution and energy crisis are nowadays considered among the most important problems facing humanity. Several strategies have been proposed to solve them, being photocatalysis a very promising one because of its ease of application and low cost. In the search for active photocatalysts, those based on graphite-like carbon nitride (g-C 3 N 4 ) are becoming good alternatives for various reactions. In this work, the properties of g-C 3 N 4 /MoS 2 /MnOOH composite material and its photocatalytic behavior for the production of hydrogen (H 2 ) under UV radiation were investigated. RESULTS:The composite material was synthesized by applying a combination of thermal condensation and hydrothermal methods. According to the results of X-ray diffraction (XRD), ultraviolet diffuse reflectance spectroscopy (UV-DRS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), good dispersion of the phases and the formation of a heterojunction were observed. The band gap value of the composite material, calculated by the Kubelka-Munk equation using the values obtained from UV-DRS analysis, was lower than those of the individual components, while it also had a much longer electron-hole recombination time, according to photoluminescence analysis. As a consequence of a synergistic effect, the activity of the proposed composite photocatalyst was superior in the reaction of water splitting, with a kinetic constant of 466 mol h −1 and a production rate of 1750 mol H 2 g −1 cat h −1 (50 and 21% higher than those obtained with MoS 2 and g-C 3 N 4 , respectively). CONCLUSION: Because of its high activity and stability, g-C 3 N 4 /MoS 2 /MnOOH composite photocatalyst is an excellent alternative for H 2 production by the water splitting reaction. REFERENCES1 Sun H and Wang S, Research advances in the synthesis of nanocarbon-based photocatalysts and their applications for photocatalytic conversion of carbon dioxide to hydrocarbon fuels. Energy Fuels 28:22-36 (2014).

No abstract

No abstract

No abstract