Santoro Carlo, Rojas-Carbonell Santiago, Awais Roxanne, Gokhale Rohan, Kodali Mounika, Serov Alexey, Artyushkova Kateryna, Atanassov Plamen
Department of Chemical and Biological Engineering, Center for Micro-Engineered Materials (CMEM), University of New Mexico, Albuquerque, NM 87131, USA.
J Power Sources. 2018 Jan 31;375:11-20. doi: 10.1016/j.jpowsour.2017.11.039.
Platinum group metal-free (PGM-free) ORR catalysts from the Fe-N-C family were synthesized using sacrificial support method (SSM) technique. Six experimental steps were used during the synthesis: 1) mixing the precursor, the metal salt, and the silica template; 2) first pyrolysis in hydrogen rich atmosphere; 3) ball milling; 4) etching the silica template using harsh acids environment; 5) the second pyrolysis in ammonia rich atmosphere; 6) final ball milling. Three independent batches were fabricated following the same procedure. The effect of each synthetic parameters on the surface chemistry and the electrocatalytic performance in neutral media was studied. Rotating ring disk electrode (RRDE) experiment showed an increase in half wave potential and limiting current after the pyrolysis steps. The additional improvement was observed after etching and performing the second pyrolysis. A similar trend was seen in microbial fuel cells (MFCs), in which the power output increased from 167 ± 2 μW cm to 214 ± 5 μW cm. X-ray Photoelectron Spectroscopy (XPS) was used to evaluate surface chemistry of catalysts obtained after each synthetic step. The changes in chemical composition were directly correlated with the improvements in performance. We report outstanding reproducibility in both composition and performance among the three different batches.
采用牺牲载体法（SSM）合成了铁氮碳系无铂族金属（PGM-free）氧还原催化剂。合成过程中使用了六个实验步骤：1）将前驱体、金属盐和二氧化硅模板混合；2）在富氢气氛中进行第一次热解；3）球磨；4）在强酸性环境中蚀刻二氧化硅模板；5）在富氨气氛中进行第二次热解；6）最后球磨。按照相同步骤制备了三个独立批次的样品。研究了各合成参数对中性介质中表面化学性质和电催化性能的影响。旋转环盘电极（RRDE）实验表明，热解步骤后半波电位和极限电流有所增加。蚀刻和进行第二次热解后观察到进一步的改善。在微生物燃料电池（MFC）中也观察到类似趋势，其功率输出从167±2μW cm增加到214±5μW cm。利用X射线光电子能谱（XPS）评估每个合成步骤后获得的催化剂的表面化学性质。化学成分的变化与性能的改善直接相关。我们报告了三个不同批次在组成和性能方面都具有出色的重现性。
