Defect enriched hierarchical iron promoted Bi2MoO6 hollow spheres as efficient electrocatalyst for water oxidation

The manipulation in crystal structure as well as electronic structure of material apart from the morphology play important role in determining electrocatalytic activity. Bismuth molybdate with its special layered structure in orthorhombic phase and hollow sphere morphology performed as potential electrocatalyst for oxygen evolution reaction in alkaline medium. The activity can further be enhanced by promoting iron in the crystal structure. The strain as well as dislocation developed in the crystal structure of Bi2MoO6 upon iron incorporation are well-studied. The presence of optimum amount of iron and thereby creating oxygen vacancies have been found to be beneficial, though higher concentration turns out to be detrimental for the electrocatalytic performance. The optimum iron promoted Bi2MoO6 leads to achieve overpotential value of 286 mV at 10 mA cm−2 current density with Tafel slope of only 44 mV dec-1 for OER. The experimental results are well-supported by the density functional theory simulations, which demonstrate that iron incorporation lowers the energy barrier by promoting the adsorptions of OER intermediates, most distinctly the oxygen adsorption.