简便的碳浴法制备N,S共掺杂类石墨烯炭提高氧还原反应性能

Improved oxygen reduction performance of a N, S co-doped graphene-like carbon prepared by a simple carbon bath method

  • 摘要: 合理设计和优化氧还原反应(ORR)非金属电催化剂对于燃料电池和金属空气电池非常重要。然而,这现在仍然是一个巨大的挑战。本工作通过简单的碳浴法成功制备了N,S共掺杂的类石墨烯炭材料(GLC),并将其用于电催化氧还原反应。经高温热解和模板分解后,得到的GLC-11具有较高的比表面积(583.68 cm2/g)和孔体积(0.63 cm3/g)。其中,微孔表面积占总表面积的29.39%,微孔体积占总孔体积的12.70%。同时,通过XPS结果计算得到,GLC-11的吡啶氮和石墨氮含量总和高达92.2%。因此,GLC-11在碱性电解液中显示出了高电催化ORR性能,其中波电位(E1/2)为0.82 VRHE,优于Pt/C(E1/2=0.80 VRHE)。此外,GLC-11催化剂与商业Pt/C(20 wt%)催化剂相比表现出更好的稳定性和优异的甲醇耐受性。

     

    Abstract: Rationally designing and optimizing metal-free electrocatalysts for the oxygen reduction reaction (ORR) is of great importance for fuel cells and metal-air batteries, but remains a great challenge. A N,S-codoped graphene-like carbon (GLC) was synthesized by a simple carbon-bath pyrolysis method, in which urea and thiourea (1:1 w/w) were used as both the sacrificial template and source of nitrogen and sulfur, and glucose as the carbon precursor. A mixture of these materials was placed in a crucible that was contained in a larger crucible full of carbon powder. Compared with N-doped or S-doped GLCs synthesized using only urea or thiourea, respectively, the N,S-codoped GLC had a pore volume of 0.63 cm3/g and a larger specific surface area of 583.68 m2/g, the highest micropore to total surface area of 29.39% and micropore to total pore volume of 12.70%, and the highest pyridinic-N and graphitic-N content of up to 92.2%. The N,S-codoped GLC showed a high electrocatalytic activity for ORR with a mid-wave potential (E1/2) of 0.82 VRHE, which was more positive than that of Pt/C (E1/2=0.80 VRHE) in an alkaline electrolyte. The N,S-codoped GLC catalyst had better stability and superior methanol tolerance compared with commercial Pt/C (20 wt%), a benchmark catalyst.

     

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