《Table 1 Catalytic performance of Pt-CVDG films with different loadings of Pt.ECSA and IF, IR, IF/IR

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《超薄可转移的铂和铂钌修饰的石墨烯薄膜作为高效甲醇氧化催化剂（英文）》

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The electrochemical behavior of Pt-CVDG films was investigated by means of cyclic voltammograms（CVs）[27].Fig.3a shows the representative CV curves of PtCVDG/GCE and Pt/C/GCE in 1.0 mol L-1H2SO4.Electrochemically active surface area（ECSA）of all the above catalysts were estimated by calculating the coulombic charge for hydrogen adsorption and assuming that the oxidation of full monolayer of H atoms on polycrystalline Pt corresponds to a charge density of210μC cm-2（Table 1）.We can see that the very little electric double layer capacitance provided by CVDG compared to Pt-CVDG from Fig.S5[36].The results in Table 1 show that all the Pt-CVDG films have higher ECSA values than Pt/C and the highest ECSA is obtained from Pt-CVDG-3（94.1 m2g-1）which is about 3 times higher than that from Pt/C catalyst（28.5 m2g-1，14.15μg cm-2）under the same conditions，suggesting that the Pt-CVDG possesses a higher dispersion and utilization of Pt NPs.The peak near 0.0 V in Fig.3a indicates the adsorption of hydrogen on the Pt fcc（100）surface site（I），and that near-0.10 V is ascribed to the adsorption of hydrogen on the fcc（111）stage site（II）（Fig.3a） [60].It has been suggested that fcc（100）surface has better electro-catalytic activity than fcc（111）surface for MOR due to its higher oxygen species adsorption capacity[61].The ratio of the peak current（I）to（II）adsorption of hydrogen are 0.80，0.81 and 0.79 for PtCVDG-1，Pt-CVDG-2 and Pt-CVDG-3，which is much higher than 0.58 in Pt/C，indicating that the Pt-CVDG films are more MOR-active than Pt/C.The MOR performance was investigated by CVs in the mixture of1.0 mol L-1H2SO4+2.0 mol L-1CH3OH solution（Fig.3b）.The specific current at the peak potential in the forward scan follows the order of Pt-CVDG-3（293.1 mA mgPt-1）>Pt-CVDG-2（253.4 mA mgPt-1）>Pt-CVDG-1（225.5 mA mgPt-1）.The specific current at the peak potential decreases with the increase of Pt loading，due to the agglomeration of NPs.And a slight increase of the onset potential for MOR（forward scan）is observed when comparing Pt-CVDG with Pt/C.It is worth noting that Pt-CVDG has a Pt mass loading of more than 80 wt.%，while the Pt loading in Pt/C is20 wt.%.To investigate the long-term stability，chronoamperometric measurements of Pt-CVDG-2 and Pt/C were performed at 0.50 V for 300 s.As shown in Fig.3c，Pt-CVDG-2 retains the higher oxidation current over the testing time，displaying the better electro-catalytic durability than Pt/C catalysts for MOR.On the other hand，we also calculated the ratio of forward-scan peak current（IF）versus reverse-scan peak current（IR），IF/IR，which is a key index for evaluating the catalyst tolerance to the accumulation of intermediate carbonaceous species.The ratio for Pt-CVDG-1，Pt-CVDG-2，PtCVDG-3 and commercial Pt/C is calculated as 1.17，1.33，1.24 and 0.72，respectively.Thus Pt-CVDG films generally have less carbonaceous accumulation and hence are much more tolerant toward CO[27，62].Both the mass activity and the anti-poisoning ability of Pt-CVDG films are superior to most of Pt-based nanostructures with Pt NPs about 3 nm in diameter（Table S1，Supporting information）[28–31，42，43，45–47].All the results above indicate that with ultrahigh ECSA and a record-high mass activity for MOR，Pt-CVDG films possess much higher catalytic efficiency and utilization than commercial Pt/C.