Synthesis of MnNiO3/Mn3O4 nanocomposites for the water electrolysis process

Abstract

The hydrothermal method was optimized to produce highly efficient, novel MnNiO3/Mn3O4 nanocomposites for water electrolysis. The predominant peak observed at 36.6° corresponds to the X-ray crystal plane orientation of (1−10) and confirmed rhombohedral phase MnNiO3. The other well-resolved peaks were attributed to MnNiO3/Mn3O4 nanocomposites. Vibrational properties and metal oxygen vibrations were revealed in Fourier transform infrared profile around ~570–620 cm−1. The oxygen vacancies and electron trapping mechanism were exposed from photoluminescence spectra. The combined morphology of nanorods and distinguished nanopetals was determined for highly active MnNiO3 nanocatalyst. The band structure and modification was thoroughly studied by employing UV-visible diffuse reflection spectra and the observed band gap was 2.8 eV for MnNiO3/Mn3O4 nanocomposites. Cyclic voltammogram and linear sweep voltammogram study were used to investigate the redox behavior and water oxidation nature of the novel MnNiO3/Mn3O4 nanocomposites. A higher OER activity of 274 mA/g at 10 mV/s was achieved for the electrode loaded with optimized electrocatalysts. The excellent conductivity and ionic mobility were confirmed by electrochemical impedance spectra. The 72-h stability test was carried out and long-time durability was reported for the optimized electrocatalysts. Thus, the present study completely dealt with the preparation of novel combinations of MnNiO3/Mn3O4 nanocomposites by using controlled synthesis techniques and the exploration of optimized candidates for efficient water electrolysis process.