Modulating lattice entropy of rutile Ru_0.28Ir_0.16Cr_0.28Mn_0.28O₂ nanostructures expedites pH-universal oxygen evolution kinetics

The fine modulation of lattice entropy in a single-phase crystal structure is a promising strategy for tailoring the electronic structure and catalytic efficiency of various catalysts. We report a novel single-phase rutile-type Ru_0.28Ir_0.16Cr_0.28Mn_0.28O₂ nanoparticles synthesized via a coprecipitation process employing an economical and eco-friendly acid-base titration in aqueous solution, and subsequently a post-calcination process as a cost-effective. This results in a cost-effective, remarkably active, and stable electrocatalyst for the oxygen evolution reaction (OER) across a wide range of pH levels. The random incorporation of Ru, Ir, Cr, and Mn elements into a single tetragonal lattice facilitates rapid water dissociation, thereby optimizing the kinetics of the Volmer step and significantly enhancing OER performance in various electrolyte conditions, including alkaline, acidic, and even neural solution, with overpotentials of 275 mV, 210 mV, and 300 mV for 10 mA cm⁻², respectively. Furthermore, Ru_0.28Ir_0.16Cr_0.28Mn_0.28O₂ nanoparticles maintain stable potential during continuous OER operation for over 75 h in 0.5 M H₂SO₄, 1 M KOH, and 0.5 M PBS solutions, confirming their excellent stability over more than 75 h under pH-universal conditions. Additionally, the synergy between experimental results and theoretical simulations reveals that the optimized energy levels enhance catalytic performance by balancing the adsorption and desorption of oxygen-containing intermediates (*OH, *O, and *OOH). This fine-tuning of electronic properties facilitates efficient OER kinetics, leading to improved catalytic activity. Our findings introduce a straightforward and environmentally friendly synthetic methodology for a single phase of rutile-type Ru_0.28Ir_0.16Cr_0.28Mn_0.28O₂ nanoparticles by modulating the lattice entropy, resulting in the unique lattice structure that can be applied as an effective OER catalyst electrode.