Saha Dipankar, Yu Hsin-Jung, Wang Jiacheng, Chen Xiaobo, Tang Chaoyun, Senger Claire, Pagaduan James Nicolas, Katsumata Reika, Carter Kenneth R, Zhou Guangwen, Bai Peng, Wu Nianqiang, Watkins James J
Conte Center for Polymer Research, Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States.
Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States.
ACS Appl Mater Interfaces. 2024 Mar 20;16(11):13729-13744. doi: 10.1021/acsami.3c18693. Epub 2024 Mar 8.
Current electrocatalysts for oxygen evolution reaction (OER) are either expensive (such as IrO, RuO) or/and exhibit high overpotential as well as sluggish kinetics. This article reports mesoporous earth-abundant iron (Fe)-nitrogen (N) doped carbon electrocatalysts with iron clusters and closely surrounding Fe-N active sites. Unique to this work is that the mechanically stable mesoporous carbon-matrix structure (79 nm in pore size) with well-dispersed nitrogen-coordinated Fe single atom-cluster is synthesized via rapid thermal annealing (RTA) within only minutes using a self-assembled bottlebrush block copolymer (BBCP) melamine-formaldehyde resin composite template. The resulting porous structure and domain size can be tuned with the degree of polymerization of the BBCP backbone, which increases the electrochemically active surface area and improves electron transfer and mass transport for an effective OER process. The optimized electrocatalyst shows a required potential of 1.48 V (versus RHE) to obtain the current density of 10 mA/cm in 1 M KOH aqueous electrolyte and a small Tafel slope of 55 mV/decade at a given overpotential of 250 mV, which is significantly lower than recently reported earth-abundant electrocatalysts. Importantly, the Fe single-atom nitrogen coordination environment facilitates the surface reconstruction into a highly active oxyhydroxide under OER conditions, as revealed by X-ray photoelectron spectroscopy and Raman spectroscopy, while the atomic clusters boost the single atoms reactive sites to prevent demetalation during the OER process. Density functional theory (DFT) calculations support that the iron nitrogen environment and reconstructed oxyhydroxides are electrocatalytically active sites as the kinetics barrier is largely reduced. This work has opened a new avenue for simple, rapid synthesis of inexpensive, earth-abundant, tailorable, mechanically stable, mesoporous carbon-coordinated single-atom electrocatalysts that can be used for renewable energy production.
目前用于析氧反应（OER）的电催化剂要么价格昂贵（如IrO、RuO），要么/并且表现出高过电位以及缓慢的动力学。本文报道了具有铁簇和紧密围绕的Fe-N活性位点的介孔富土铁（Fe）-氮（N）掺杂碳电催化剂。这项工作的独特之处在于，使用自组装的瓶刷嵌段共聚物（BBCP）三聚氰胺-甲醛树脂复合材料模板，通过仅在几分钟内的快速热退火（RTA），合成了具有良好分散的氮配位Fe单原子簇的机械稳定介孔碳基质结构（孔径79nm）。所得的多孔结构和畴尺寸可以通过BBCP主链的聚合度进行调节，这增加了电化学活性表面积，并改善了电子转移和质量传输，以实现有效的OER过程。优化后的电催化剂在1M KOH水溶液电解质中获得10mA/cm²电流密度时所需电位为1.48V（相对于RHE），在给定过电位250mV时塔菲尔斜率为55mV/decade，这明显低于最近报道的富土电催化剂。重要的是，X射线光电子能谱和拉曼光谱表明，Fe单原子氮配位环境有助于在OER条件下将表面重构为高活性的羟基氧化物，而原子簇增强了单原子活性位点，以防止在OER过程中脱金属。密度泛函理论（DFT）计算支持铁氮环境和重构的羟基氧化物是电催化活性位点，因为动力学障碍大大降低。这项工作为简单、快速合成可用于可再生能源生产的廉价、富土、可定制、机械稳定的介孔碳配位单原子电催化剂开辟了一条新途径。
