Lead-Induced Microstrain in Synthesis and Manipulation of Porous Pyrochlore for Boosting Oxygen Evolution Reaction

Abstract

Pyrochlore ruthenates are highlighted as candidates to replace iridium oxide as oxygen evolution reaction (OER) electrocatalyst, but their designable geometric configurations and composition modulations are hampered by the high-temperature (≈1100 °C) and long-time calcination (more than 12 h), which further decreases the technical and economic feasibility. In this work, an energy- and time-saving approach is proposed to prepare pyrochlore yttrium ruthenate at a much lower calcination temperature (600 °C) and shorter calcination time (6 h) just by inducing A-site substitutions of lead ions (YPRO). The local microstrain derived from Pb provides the surficial compression and extra driving force to overcome the strain energy of phase-transition resistances and the obtained low-temperature YPRO exhibits enriched pores, deficient geometries, shortened Ru─O bond, and enlarged Ru─O─Ru bond angle, which further modify the electronic structure, involving of the rearranged band alignment and the eliminated bandgap. The regulated morphologic, geometric, and electronic structures in YPRO synergically boost the electrocatalytic OER performance (4.8-fold and 30.0-fold enhancements compared with pyrochlore yttrium ruthenate and commercial iridium dioxide (IrO2), respectively) in universal pH conditions. This substitution-induced strain engineering on phase transition should also be effective for other high-temperature materials and trigger their diverse intriguing properties.