铋牺牲法制备石墨烯负载Fe-N单原子位点增效氧还原催化和锌-空气电池性能  

Enhancing oxygen reduction of Fe-N-C active sites onto graphene via bismuth sacrifice for Zn-air batteries

作　　者：杨志远 张燕 肖娟定 王俊英[2] 王俊中 Zhiyuan Yang;Yan Zhang;Juanding Xiao;Junying Wang;Junzhong Wang(Institutes of Physical Science and Information Technology,Anhui Graphene Carbon Fiber Materials Research Center,Anhui University,Hefei 230601,Anhui,China;Shanxi Key Laboratory of Carbon Materials,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,Shanxi,China)

机构地区：[1]安徽大学物质科学与信息技术研究院,安徽石墨烯碳纤维材料工程研究中心,安徽合肥230601 [2]中国科学院山西煤炭化学研究所,炭材料山西省重点实验室,山西太原030001

出　　处：《Chinese Journal of Catalysis》2024年第4期272-281,共10页催化学报（英文）

基　　金：国家自然科学基金(22279001);国家自然科学基金(22179138);山西省自然科学基金(20210302123005);安徽省重大科技专项项目(2022e03020007)。

摘　　要：催化氧反应(ORR)是锌空电池和氢燃料电池能量转化的关键过程,然而其反应速率往往较低,因此开发高活性且耐久的催化材料至关重要.当前,研发低成本、高效率且稳定的氧还原催化剂已成为国内外的研究热点.其中,富含金属-氮-碳活性位点的低成本ORR催化材料,因其具有替代贵金属的潜力,成为重要的候选材料.然而,在制备这类催化剂时,所用分子前驱体在热解过程中易团聚形成金属基硬颗粒,如何减少热解过程中金属成分的自发聚集和不良副产物的生成,提高活性单原子的利用率,特别是在使用廉价分子前驱体(如三聚氰胺和铁盐)时,仍面临挑战.本研究旨在探索有效的制备策略,以优化催化剂性能,推动其在能源转换领域的应用.本文报道了一种以硝酸铋为牺牲剂,石墨烯为导电载体,通过热解廉价的三聚氰胺和铁盐,合成石墨烯负载丰富Fe-N-C活性位点催化剂的新方法.该方法中硝酸铋前驱体高温热解生成的铋铁合金或氧化铋因表面没有碳层,而容易被热酸除去,形成更多的可接近的FeNx活性位点,从而有效地抑制铁基颗粒和管状碳结构的形成,实现了催化剂的高效合成.双球差矫正电镜、X-射线光电子能谱和X-射线吸收结构光谱等表征证明,铋化合物去除后留下空位被铁原子取代,增加了Fe-N-C位点密度,并且铁以单原子活性位形式存在.实验结果表明,所制备的催化剂表现出高氧还原性能,在碱性和酸性条件下的半波电位分别为0.916和0.784 V.石墨烯基催化剂的动力学电流密度(0.9 V vs.RHE)达到10.41 mA cm^(-2),是不加铋化合物样品的6倍,贵金属Pt/C催化剂的4倍.此外,催化剂的塔菲尔斜率为59 mV dec^(-1),低于不加铋化合物样品(80 mV dec^(-1))、不加石墨烯样品(93 mV dec^(-1))、无金属样品(88 mV dec^(-1))和Pt/C(80 mV dec^(-1)).在0.1 mol L^(-1) KOH条件下,催化剂循环10000圈后,半波电位仅衰减15 mV,低于PtSynthesizing low-cost electrocatalysts with rich metal-nitrogen-carbon active sites for the oxygen reduction reaction(ORR)is critical for developing high-performance Zn-air batteries.However,it is challenging for the pyrolysis cheap molecular precursors(such as melamine and iron salts)is challenging because of the spontaneous aggregation of metal components and undesired byproducts during pyrolysis.Herein,we describe an approach to generate graphene-supported accessible Fe-N-C active sites by introducing a removable bismuth compound that efficiently inhibits the formation of iron-related particles and tubular carbon structures.The graphene-supported Fe(Bi)-N-C electrocatalyst exhibited high ORR activity under both alkaline(E1/2~0.916 V)and acidic(E1/2~0.784 V)conditions,along with excellent durability(15 mV degradation after 10 k cycles accelerated test).Using the catalytic material as the cathode,the Zn-air battery delivered a high power density of 201.4 mW cm^(-2) and a high stability over 1000 cycles.This investigation presents a promising controlled pyrolysis solution for the scalable synthesis of low-cost,high-performance metal-nitrogen-carbon-based catalytic materials.

关 键 词：氧还原反应 铋 石墨烯 锌-空气电池 Fe-N-C 

分 类 号：TQ426[化学工程] TM911.41[电气工程—电力电子与电力传动]