Mild Catalytic‐Crystallization‐Confinement Synthesis of Single‐Atom Catalyst on α‐MnO 2 With Hundreds‐Fold Enhanced Water Oxidation Activity

Single‐atom catalysts anchored on metal oxide supports (SACs/MO x ) present exceptional activities toward oxygen evolution reaction (OER), owing to the strong metal‐support interactions, maximum atom utilization, and good stability under high oxidation environments. However, conventional synthesis of SACs/MO x involves uncontrollable procedures and harsh conditions, hindering their atomic dispersion and scalable manufacturing. Here, we report a catalytic‐crystallization‐confinement approach for synthesizing SACs on α‐MnO 2 under low temperature and ambient pressure. This approach leverages noble‐metal atoms to mediate the dissolution‐recrystallization of amorphous oxide precursors, confining the noble‐metal single atoms within the lattice, and lowering the crystallization temperature of the precursor. The fabrication is scalable and generalizable, allowing the synthesis of diverse SACs (e.g. Ir, Ru, Pd, Pt) on α‐MnO 2 support. The representative Ir‐single‐atom/α‐MnO 2 exhibits a ∼300‐fold OER activity enhancement over commercial IrO 2 . This work opens a new avenue for the mild and scalable synthesis of SACs and provides new insight into crystallization mechanism of oxides.