以碳布为基体将室温原位生长、高温碳化处理与电沉积方法相结合,制备出具有高活性的铂@钴@氮碳(Pt@Co-N-C@CC)复合材料,研究了这种多层级复合催化阴极材料在海水介质中的电催化氧还原性能.结果表明,这种复合材料具有底层微孔Co-N-C、表层Pt纳米簇的多层次包覆结构,其中ZIF8/ZIF67混合碳化底层提供铂负载位点,有利于Pt纳米颗粒的附着生长,提高了 Pt纳米颗粒的分散性.与商业Pt/C催化剂(-0.028 V和-0.401 V vs.Ag/AgCl)相比,Pt@Co-N-C@CC复合材料的氧还原性能较高,其氧还原起始电位和半波电位分别0.075 V和-0.156 V(vs.Ag/AgCl);与Mg组装的电池,Pt@Co-N-C@CC在5 mA/cm2下的恒流放电电压高于0.8 V,最大功率密度达到7.6 mW/cm2.这种金属有机骨架ZIF8/67衍生的Co-N-C结构与纳米Pt复合,有利于提高Pt的催化活性和抗Cl-毒化.
Abstract
Aiming at the problem of low chloride-poisoning resistance capacity and low electrocatalyt-ic activity for the catalytic material of oxygen reduction,hierarchical composite material was synthesized and its oxygen reduction process was studied in the natural seawater.Herein,A highly active material of hierarchical Pt@Co@-N-C composite coating on carbon cloth was prepared via a combined technique composed of in-situ growth method,high-temperature carbonization treatment and electrodeposition.Characterization results indicate that the as-synthesized composite displays a multi-layered core-shell en-capsulation structure with carbon fibers serving as the core matrix,ZIF8/ZIF67-deriving microporous Co-N-C as the bottom coating and the electrodeposited Pt nanoclusters as the apparent catalytic coating.Whereinto,the Co-N-C coating provides lots of depositing sites for improving the dispersibility of Pt nanoparticles,expediting the uniform growth of Pt nanoclusters.Electrochemical results show that in com-parison to the commercial PVC catalyst,Pt@Co-N-C@CC possesses better electrocatalytic oxygen re-duction performance,i.e.which presents onset potential 0.075 V and half-wave potential-0.156 V all much more positive than those of the commercial ones-0.028 V and-0.401 V(vs.Ag/AgCI)respectively.The seawater battery assembling Pt@Co-N-C@CC and Mg shows higher cell voltage of above 0.8 V and maximum power density of 7.6 mW/cm2,in contrary,below 0.5 V and 3.9 mW/cm2 respectively for the as-sembling Pt/C and Mg.These prove that the high-efficiency recombination of ZIF8/ZIF67-deriving Co-N-C and Pt nanoclusters benefits to enhance the catalytic activity and improve the chloride-poisoning resis-tance.
维普
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