Effective Strain Engineering of IrO2 Toward Improved Oxygen Evolution Catalysis through a Catalyst-Support System

A template-free, one-step synthesis of nano-IrO2 on a layered Mn-Co birnessite support was developed to induce the catalyst-support interaction. The IrO2 nanoparticles were prepared with inherent crystal lattice strain, which is derived from the Ir-O-Mn mismatch at the interface. The oxidation state of iridium is higher than Ir-IV, revealing the electron transfer to the substrate. On account of the crystal lattice distortion and electronic manipulations being favorable to the oxygen evolution reaction (OER), the as-synthesized composite exhibited excellent OER activity and stability. The improved catalytic nature was followed by enhancement in the electrochemical active surface area, mass specific activity, and intrinsic activity. Moreover, the Tafel slope of 42 mV dec(-1) reveals better reaction kinetics for IrO2/Mn-Co (2 : 1)-birnessite than many previously reported catalysts despite the low precious noble metal content in the as-synthesized composite. Conclusively, we have proven that the strain engineering holds vital importance in forming catalyst-support interaction and rational design of catalysts.