NiFe2O4 spinel ferrite and h-BN nanosheets coalescence for superior electrocatalytic oxygen evolution reaction

In electrocatalyst based water electrolysis, the half reaction of oxygen evolution has slow kinetics compared to the other half reaction of hydrogen production. The use of metal oxide hybridized heterostructure (HS) catalyst is considered as cost-effective strategy for oxygen evolution applications than the noble metal catalyst. Here, we synthesized nickel ferrite (NiFe2O4) nanoparticles by thermal decomposition of citrate complex of corresponding metals. Further, nickel ferrite/boron nitrite (NiFe2O4/h-BN) heterostructure catalysts were synthesized by the exfoliation method (ultrasonication) with different ratio of h-BN (75 mg and 150 mg). The prepared heterostructure catalysts were characterized using Fourier-transform infrared (FTIR) spectroscopy to study the chemical bonding. X-ray diffraction spectroscopy (XRD) confirmed that the crystal structure of NiFe2O4 as a spinel ferrite. High resolution scanning electron microscopy (HRSEM) images revealed that NiFe2O4 nanoparticles were embedded on the surface of BN nanosheets. X-ray Photoelectron spectroscopy (XPS) was used to analysis the oxidation states of the constituent elements. Brunauer-Emmett-Teller (BET) was conducted to study the porosity and surface area of developed HS, it's revealed that NiFe2O4/h-BN-75 HS had higher pore volume and pore size (0.037 cm(3)/g and 3.5 nm) than bare NiFe2O4. All the electrocatalysts were loaded on the carbon cloth to make electrodes for oxygen evolution reaction analysis. The electrochemical measurements were conducted to explore the electrocatalytic behaviour of carbon cloth loaded electrodes. NiFe2O4/h-BN-75 heterostructure catalyst showed reduced overpotential similar to 431 mV with lower Tafel slope and lower charge transfer resistance values of 127.8 mV dec(-1) and 9.6 Omega, respectively. These properties of NiFe2O4/h-BN-75 significantly enhanced the kinetics of oxygen evolution reaction than the bare NiFe2O4 nanoparticles. These results, demonstrate that the synthesis and fabrication methods are significant to improve the electrocatalytic behavior of heterostructure catalyst with cost effectiveness.