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Hybrid materials based on montmorillonite functionalized with LaMnO3 perovskitic structures were obtained for the first time by ultrasonic method with sonotrode immersed in the reaction medium, followed by heat treatment at a temperature of 600 °C. The clay mineral montmorillonite (Mmt), sodium montmorillonite (Mmt-Na+) and functionalized material (Mmt-LMO) were characterized by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM/Edx) techniques. The XRD patterns of Mmt-LMO composites show both the presence of the perovskitic phase with orthorhombic structure, and a mixture of aluminosilicates, corresponding to the montmorillonite clay minerals. The (Mmt), (Mmt-Na+) minerals and (Mmt-LMO) hybrid material were used to manufacture modified electrodes whose catalytic properties for the oxygen and hydrogen evolution reactions were investigated in alkaline medium. Based on electrochemical experimental results, some of these electrodes are catalytically active toward the hydrogen evolution reaction and the more performant ones were investigated further and it was found that the electrode modified with the composition containing 6 mg LaMnO3 functionalized montmorillonite and 10 µL Nafion solutions have the best electrocatalytic properties. At the current density of −10 mA/cm2 the electrode exhibits an over potentialfor hydrogen evolution of −0.48 V and its Tafel slope was measured to be 70 mV/dec. This study complements the extant scientific knowledge relevant to the water splitting domain.

Ni11□(HPO3)8(OH)6 nanorods were the focus of three different studies. First, the thermal behaviour of the material was investigated and it outlined a good thermal stability up to 400 °C. Second, a comparative electrochemical study concerning the OER performance in alkaline medium of several graphite electrodes modified with the nickel phosphite was performed. The most promising electrodes were further characterised electrochemically and the electrode modified with Nafion solution and 5 mg Ni11□(HPO3)8(OH)6 exhibited the smallest overpotential value at the 10 mA cm−2 anodic current density (0.59 V), as well as the smallest Tafel slope (0.081 V dec−1). Furthermore, the constant potential electrolysis test revealed that this electrode is fairly stable within a time span of 300 min. Third, the capacity of Ni11□ (HPO3)8(OH)6 nanorods to remove MB and RhB were investigated under simulated visible light irradiation and positive results were obtained for the application as visible-light active photocatalyst. All this together corroborated with the eco-friendly nature of the materials, reinforces the fact that the phosphite type compound is a promising candidate for the design of new multifunctional and advanced materials.