conditions at 25 °C, while that of proton exchange membrane fuel cells is 0.83. Due to sluggish kinetics, poor methanol tolerance, and susceptibility to CO poisoning for the state-of-the-art Platinum (Pt) electrocatalyst at the cathode side, the oxygen reduction reaction (ORR) is the main process in practical DMFCs, delaying the commercialization of DMFCs significantly. Therefore, significant research efforts are being focused on the development of highperformance alternatives to Pt materials. Among the various potential ORR electrocatalysts, Palladium (Pd)-based electrocatalysts are the most promising substitutes for Pt in alkaline electrolytes. [1][2][3][4] It is believed that the surface composition, size, and shape of the electrocatalysts seriously affect their ORR performances because of surface atomic arrangement, defect, electronic effect, and surface strain. [5][6][7][8][9][10] In a variety of nanostructures, the ultrathin 2D nanostructures have received extensive attention due to their intrinsic advantages, such as high surface metal atom to volume ratio and abundant low-coordinated atoms (e.g., topmost surface atoms and edge atoms). [11][12][13][14][15] Moreover, lattice strains, geometric effects, and ensemble effects present in multimetallic catalysts often boost the ORR activities. [16][17][18][19][20][21] Due to Ultrathin 2D metal nanostructures have sparked a lot of research interest because of their improved electrocatalytic properties for fuel cells. So far, no effective technique for preparing ultrathin 2D Pd-based metal nanostructures with more than three compositions has been published. Herein, a new visible-light-induced template technique for producing PdAuBiTe alloyed 2D ultrathin nanosheets is developed. The mass activity of the PdAuBiTe nanosheets against the oxygen reduction reaction (ORR) is 2.48 A mg Pd −1, which is 27.5/17.7 times that of industrial Pd/C/Pt/C, respectively. After 10 000 potential cyclings, there is no decrease in ORR activity. The PdAuBiTe nanosheets exhibit high methanol tolerance and in situ anti-CO poisoning properties. The PdAuBiTe nanosheets, as cathode electrocatalysts in direct methanol fuel cells, can thus give significant improvement in terms of power density and durability. In O 2 /air, the power density can be increased to 235.7/173.5 mW cm −2 , higher than that reported in previous work, and which is 2.32/3.59 times higher than Pt/C.
