Scheme 1. (a) Diagram of the carbothermal installation. (b) Temperature profile as a function of time during calcination of amorphous carbon using a carbothermal approach. (c) Schematic illustrating the synthesis of the highly graphitic carbon supports G-BC-S and PtCo/G-BC-S.

Fig. 1. Characterization of the carbon supports before and after graphitization treatment. (a) XRD spectra; (b) Raman spectra; (c) XPS spectra; (d) N2 adsorption-desorption isothermal curves; (e) Pore size distribution; (f) Conductivity diagram.

Fig. 2. SEM, TEM, and HRTEM images of BC (a-c), G-BC-S (d-f), and G-BC-F (g-i). The insets in (c), (f), and (i) show the corresponding structure.

Fig. 3. (a) XRD patterns of PtCo/G-BC-S, PtCo/BC, and JM Pt/C. (b) TEM image of PtCo/BC. (c) TEM image of PtCo/G-BC-S, insets: particle size distributions. (d-f) HAADF-STEM images of L10 ordered PtCo in PtCo/G-BC-S. (g) Schematic of L10 PtCo nanoparticle with 2-3 Pt atomic layers. (h) The unit L10 ordered PtCo. Blue and yellow atoms represent Pt and Co, respectively.

Fig. 4. Electrochemical performance test on an RDE. (a) CVs of the electrocatalysts in 0.1 mol L-1 HClO4 solution. (b) ORR polarization curves in O2-saturated 0.1 mol L-1 HClO4. Rotation rate: 1600 r min-1; sweep rate: 10 mV s-1. Comparison of ORR (c) and single fuel cell performance (e) of previously reported PtCo-based catalysts [43????????????-56]. (d) H2-air fuel polarization plots and power density plots. LSV (f) and mass and specific activities (g) at 0.9 V (vs. RHE) of PtCo/ BC, PtCo/ G-BC-S, and Pt/C before and after 20 K cycles AST. (h,i) TEM image and histograms of PtCo/ BC, PtCo/G-BC-S after AST, respectively.

Fig. 5. (a) Representative models of intermediates adsorbed on the Pt (111) surface involved in the associative ORR mechanism. (b) Diagram of free energy estimated using DFT for the associative ORR on L10-Co@2Pt(111) and Pt (111). (c, d) Differential charge density images of O* intermediates adsorbed on L10-Co@2Pt(111) and Pt (111). The isosurface value is 0.006 e ?-3.