The widespread commercial application of direct formate fuel cell(DFFC)is limited by the lack of efficient electrocatalysts for the formate oxidation reaction(FOR).AgPdCo hollow nanospheres(H-NSs)with jagged surfaces are successfully synthesized via a facile method involving the wet-chemical synthesis of AgPdCo nanospheres(NSs)and galvanic replacement reaction between Pd salt and AgPdCo NSs.Surpassing Ag_(30)Pd_(69)Co_(1) NSs and most of previously reported electrocatalysts,Ag_(9)Pd_(90)Co_(1) H-NSs exhibit extremely high FOR activity with a peak current density of 3.08 A·mg_(Pd)^(−1).Apart from the competitive activity,Ag_(9)Pd_(90)Co_(1) H-NSs show greatly improved chronoamperometric and cycling stability,whereby the current density retains about 0.24 A·mg_(Pd)^(−1) after 3,600 s electrocatalysis and the mass activity maintains 54.06%of the initial value after 500 cycles.The unique hollow nanosphere and synergistic effect are responsible for the enhanced activity and stability.This study will provide new clues for the development of outstanding electrocatalysts.
We investigate the effects of shape and single-atom doping on the structural, optical absorption, Raman, and vibra- tional properties of Ag13, Ag12CUl, CUl3, and Cul2Agl clusters by using the （time-dependent） density functional the- ory. The results show that the most stable structures are cuboctahedron （COh） for Ag13 and icosahedron （Ih） for CUl3, Agl2CUlcore, and Cul2Aglsur. In the visible-near infrared optical absorption, the transitions consist of the interband and the intraband transitions. Moreover, red shifts are observed as follows： 1） clusters change from Agl2CUlcore to Ag13 to Ag12Culsur with the same motifs, 2） the shapes of pure Agl3 and Agl2CUlcore clusters change from COh to Ih to decahe- dron （Dh）, 3） the shape of Agl2CUlsur clusters changes from Ih to COh to Dh, and 4） the shapes of pure CU13 and Cu12Agl clusters change from Ih to Dh to COb. All of the Raman and vibrational spectra exhibit many significant vibrational modes related to the shapes and the compositions of the clusters. The ranges of vibrational spectra of Ag13, Agl2CUl or CU13, and Cu12Agl clusters become narrower and the vibrational intensities increase as the shape of the clusters changes from Ih to Dh to COh.
