Sequential Constructing Pt‐Mo‐NG Single‐Atom/Nanoparticle Cooperative Catalytic System for Boosting the Methanol Oxidation Performance

ABSTRACT Rational design single atoms and nanoparticles cooperative catalyst presents great potential for addressing the insufficient performance and high cost of Pt‐based anode catalysts in direct methanol fuel cells. Specifically, for bimetallic catalysts, the deposition sequence of metals is crucial to their synergistic effect, yet its significance is frequently neglected in single‐atom/nanoparticle synergy systems. Herein, we fabricate a well‐defined Pt‐Mo‐NG catalyst using atomic layer deposition. It suggests that the pre‐deposited Mo single atoms can act as nucleation sites for Pt nanoparticles, thereby inhibiting Pt agglomeration. Meanwhile, the isolated Mo atoms facilitated water dissociation, effectively compensating for the deficiencies of Pt nanoparticles. Methanol oxidation reaction (MOR) tests demonstrate that the Pt‐Mo‐NG catalyst exhibits higher mass activity (2037.76 mA mg Pt −1 ) compared to Mo/Pt‐NG with the reversed deposition sequence, which is 5.82 times that of commercial 20% Pt/C. It also demonstrates excellent stability and superior CO tolerance. Mechanism study reveals that Mo single atoms optimize the d‐band center of Pt, weaken Pt‐CO adsorption, and accelerate water dissociation to generate *OH, thereby efficiently removing CO intermediates. This work highlights the critical influence of deposition sequence on the synergy between single atoms and nanoparticles, providing a new perspective for developing efficient and stable Pt‐based catalysts.