Hydrogen Insertion Optimizes the Electronic State of Pd–Ir Nanoalloys to Enhance Methanol Electrocatalytic Oxidation

Abstract

The optimized electronic state of an electrocatalyst is a powerful approach to promoting the methanol oxidation reaction (MOR). In this work, H incorporated into the Pd–Ir alloy decorated on nitrogen-doped graphene (designated as Pd₇IrH_x/NG) was fabricated through a mild method. As an electrocatalyst for MOR in alkaline media, Pd₇IrH_x/NG achieves a catalytic activity of 1625.0 mA mg^–1 (mass activity) and 5.9 mA cm^–2 (specific activity), along with exceptional long-term cycle stability. This far exceeds those of Pd₇Ir/NG, PdH_x/NG, Pd/NG, and commercial Pd/C catalysts. Structural characterization reveals that the electronic states of Pd and Ir in Pd₇IrH_x/NG in terms of binding energy and the ratio of zerovalent to oxidized metals were efficiently optimized through hydrogen insertion. Consequently, this modification creates more channels for the dual-coupled transfer of electrons and protons. This not only supplies an ample amount of active hydroxyl species but also optimizes the adsorption of intermediates. The results highlight the importance of optimizing the electronic state and provide an efficient strategy to design advanced electrocatalysts for small organic molecular electro-oxidation.