Enhanced oxygen evolution reaction activity of optimized strontium/chitosan-magnesium ferrite heterostructure: Combined experimental and theoretical insights

In this work, ternary heterostructure electrocatalysts strontium/chitosan-magnesium ferrite nanostructures (Sr/CS-MgFe₂O₄ NSs) are prepared by a co-precipitation approach. The ternary system comprises chitosan (CS) nanorods overlapped with magnesium ferrite (MgFe₂O₄) nanoparticles, forming a network with the addition of strontium (Sr). A significant increase in porosity, surface area, stability, and the number of active sites accounts for efficient oxygen evolution reaction (OER) activity. A diverse range of characterizations is employed to investigate the crystal structure, functional groups, optical properties, elemental composition, morphology, chemical analysis, surface area, and pore size of the synthesized samples. Optimized Sr/CS-MgFe₂O₄ exhibits significant OER activity and stability, a minimal overpotential of 200 mV (mV), and a lower Tafel slope value of 48 mV dec⁻¹. Optimum sample (2 wt. % Sr doped CS-MgFe₂O₄ showed higher conductivity, small semicircle with low electron transfer impedence as confirmed by the Nyquist plot and stability was tested using chronoamperometric analysis. First-principles calculations of hydroxyl (-OH) adsorption energies on undoped, CS-MgFe₂O₄, and Sr doped CS-MgFe₂O₄ surfaces suggest that the Sr/CS-doped surface enhances OER activity. This study introduces innovative strategy to developing low cost, stable electrocatalysts for electrochemical water splitting.