Tuning the Activity of Carbon for Electrocatalytic Hydrogen Evolution via an Iridium‐Cobalt Alloy Core Encapsulated in Nitrogen‐Doped Carbon Cages

<jats:title>Abstract</jats:title><jats:p>Graphene, a 2D material consisting of a single layer of sp<jats:sup>2</jats:sup>‐hybridized carbon, exhibits inert activity as an electrocatalyst, while the incorporation of heteroatoms (such as N) into the framework can tune its electronic properties. Because of the different electronegativity between N and C atoms, electrons will transfer from C to N in N‐doped graphene nanosheets, changing inert C atoms adjacent to the N‐dopants into active sites. Notwithstanding the achieved progress, its intrinsic activity in acidic media is still far from Pt/C. Here, a facile annealing strategy is adopted for Ir‐doped metal‐organic frameworks to synthesize IrCo nanoalloys encapsulated in N‐doped graphene layers. The highly active electrocatalyst, with remarkably reduced Ir loading (1.56 wt%), achieves an ultralow Tafel slope of 23 mV dec<jats:sup>−1</jats:sup> and an overpotential of only 24 mV at a current density of 10 mA cm<jats:sup>−2</jats:sup> in 0.5 <jats:sc>m</jats:sc> sulfuric acid solution. Such superior performance is even superior to the noble‐metal catalyst Pt. Surface structural and computational studies reveal that the superior behavior originates from the decreased Δ<jats:italic>G</jats:italic><jats:sub>H*</jats:sub> for HER induced by the electrons transferred from the alloy core to the graphene layers, which is beneficial for enhancing CH binding.</jats:p>