Synthesis, structural, optical and photocatalytic characteristics of (1−x)NiCo ₂ O ₄ /(x)NiFe ₂ O ₄ nanocomposites for hydrogen production

Abstract

Nanocomposite [Formula: see text]NiCo 2 O 4 /(x)NiFe 2 O 4 samples were fabricated utilizing the sol-gel and hydrothermal approaches. The observed X-ray diffraction patterns and Rietveld analysis were employed to examine the impact of the alloying parameter (x) on the resultant phases, their crystal structure, and microstructure for every sample. Raman spectroscopy confirmed the cation exchange between the formed phases. All samples exhibited a significant absorption within the 300–800[Formula: see text]nm range; however, it reduced a little upon increasing (x). The optical band gap energy of NiCo 2 O 4 is 0.82[Formula: see text]eV, and it is enlarged to 0.88, 1.01 and 1.73[Formula: see text]eV as the concentration of NiFe 2 O 4 in the system increases to 10, 20, and 100%. The rate of H 2 volume production during the hydrolysis of NaBH 4 is augmented by the incorporation of NiCo 2 O 4 and NiFe 2 O 4 , achieving optimal performance at [Formula: see text]. The enthalpy ([Formula: see text]), entropy ([Formula: see text]) of the activation of reactant and free energy change ([Formula: see text] values were determined. The incorporation of NiFe 2 O 4 with NiCo 2 O 4 effectively diminishes the activation energy ([Formula: see text]), enthalpy ([Formula: see text]), and entropy ([Formula: see text]) associated with NaBH 4 hydrolysis owing to synergistic electronic and structural interactions at the heterojunction interface. These modifications enhance catalytic kinetics by optimizing the transition state for H 2 production.