Size-Controlled Synthesis of IrO_2 Nanoparticles at High Temperatures for the Oxygen Evolution Reaction

摘要

Iridium oxide is the state-of-the-art catalyst for electrochemical wateroxidation in an acidic medium. Despite being one of the rarest elements inthe Earth’s crust, there is a pressing need to maximize the utilization andlongevity of active iridium centers. While conventional low-temperaturesynthesis can yield nanostructures with high mass-specific activity, they areoften insufficiently stable during water oxidation. Structurally ordered iridiumoxide is one of the most stable electrocatalysts utilized in polymer electrolytemembrane water electrolysis that benefits from the chemically orderedstructure. However, its preparation requires thermal treatment at hightemperatures, which improves its durability but can also result in reducedsurface area and altered particle morphology. In this study, the challenge ofcontrolling nanoparticle size during the preparation of structurally orderediridium oxide is successfully addressed, which typically requireshigh-temperature thermal treatment. By utilizing a silica nanoreactor as ahard template, a precise control is achieved over the nanoparticle size duringhigh-temperature thermal treatment. This approach maintains high durabilitywhile avoiding the common problem of reduced surface area and alteredparticle morphology. Specifically, this study is able to synthesize iridium oxidenanoparticles at temperatures up to 800 °C, while keeping their dimensionsbelow 10 nm.