氢氧化钾活化制备可再生多孔碳及其电催化氧还原性能研究（英文）

Renewable Porous Carbons Prepared by KOH Activation as Oxygen Reduction Electrocatalysts

氧还原反应缓慢的动力学过程严重限制了燃料电池的能量转换效率,而商用Pt/C催化剂成本太高、资源稀缺、稳定性差,需要寻找合适的材料来取代商用的Pt/C催化剂。近年来,氮掺杂多孔碳材料因其独特的物理和化学特性吸引了大量的关注。本文使用富含氮元素的可再生土豆作为生物质前驱体,通过简单的一步热解过程和KOH活化方法相结合制备出了一系列氮掺杂多孔碳电催化剂;并系统研究了KOH用量和活化温度对碳基体孔结构和电催化性能的影响。结果表明,当活化温度为750℃、KOH与碳的质量比为3/1时,所制备的催化剂(NPC-750)的氧还原活性最高,起始电位和半波电位分别达到0.89和0.79V(vs.RHE),极限电流密度达到5.53mA·cm^–2。NPC-750优异的氧还原催化活性主要归因于其发达的孔结构、高的比表面积(1134.2m^2·g^–1)和合适的氮含量(1.57at%)。同时,优异的循环稳定性和抗甲醇中毒性能进一步说明这些生物多孔碳材料是潜在的低成本氧还原电催化剂。此外,这些高比表面积多孔碳在超级电容、吸附/分离、催化以及电池等领域也具有潜在的应用前景。

The nitrogen-doped porous carbon applied for oxygen reduction reaction(ORR) has aroused extensive interests due to its unique physical and chemical properties. However, the complicated nitrogen-doping strategy and high cost limit its extensive application. In this work, a series of nitrogen-doped porous carbons were prepared by a facile pyrolysis process coupling with subsequent KOH activation using renewable N-enriched biomass potato as carbon source. Effects of activation temperature and KOH amounts on the textural properties and electrocatalytic ORR activities of the final samples were investigated in detail. The KOH activation treatment results in a high specific surface area(SSA) and hierarchical porous structure, which is beneficial for improved ORR performance. The optimized NPC-750 possesses a high SSA of 1134.2 m^2·g^–1, developed hierarchical pores as well as moderate nitrogen content(1.57 at%). It also exhibits a positive onset potential of 0.89 V(vs. RHE) and half-wave potential of 0.79 V(vs. RHE). Simultaneously, the advanced long-time stability and methanol-tolerance capacity were also obtained, implying that these biomass-derived porous carbons are potential low-cost ORR electrocatalysts. Moreover, these porous carbons show great potential in various fields including supercapacitors, adsorption/separation, catalysis and batteries as well.