Anandha Ganesh P, Prakrthi A N, Selva Chandrasekaran S, Jeyakumar D
State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi'an Jiaotong University No. 28, Xianning West Road Xi'an 710049 Shaanxi China
Centre for Nanoscience and Engineering, Indian Institute of Science Bangalore-560012 Karnataka India.
RSC Adv. 2021 Jul 16;11(40):24872-24882. doi: 10.1039/d1ra02718b. eCollection 2021 Jul 13.
Exploring non-platinum group metal (n-PGM) based efficient oxygen reduction reaction (ORR) electro-catalysts is highly important for realizing advancement in sustainable next generation-alkaline anion exchange membrane fuel cells (AAEMFCs). Herein, we demonstrate a new "hierarchical shape tuning approach" for the synthesis of controlled sized and shaped non-PGM based Ag ORR electro-catalysts with surface active nano-islands. Hierarchical shapes ranging from spherical (S-AgNs), worm-in-sphere, sphere-in-worm and vermiform (worm-like) Ag nanostructures (V-AgNs) were obtained by precisely varying the ratios of capping agent to dual reducing agents in water at ambient conditions. Compared to S-AgNs, V-AgNs revealed a higher mass normalized ORR Tafel activity (0.303 A mg at 0.9 V), onset (1.06 V) and half wave (0.78 V) potentials and higher retention of limiting current density (>88%) after 5000 cycles in 0.5 M potassium hydroxide (KOH) solution attributable to their unique worm like morphology with surface active nano-islands and support free-nature enabled better catalyst utilization. In a fully "non-PGM AAEMFC" (n-PAAEMFC), V-AgNs exhibited the highest fuel cell activity of 115.6 mW cm and stable short-term durability (∼240 h) compared to S-AgNs (41.3 mW cm) and previously reported fully n-PAAEMFCs indicating their potential use in next-generation alkaline fuel cells.
探索基于非铂族金属（n-PGM）的高效氧还原反应（ORR）电催化剂对于实现可持续下一代碱性阴离子交换膜燃料电池（AAEMFC）的进步至关重要。在此，我们展示了一种新的“分级形状调控方法”，用于合成具有表面活性纳米岛的尺寸和形状可控的基于非铂族金属的银ORR电催化剂。通过在环境条件下精确改变水中封端剂与双还原剂的比例，获得了从球形（S-AgNs）、球中蠕虫、蠕虫中球和蠕虫状（类蠕虫）银纳米结构（V-AgNs）的分级形状。与S-AgNs相比，V-AgNs在0.5 M氢氧化钾（KOH）溶液中5000次循环后显示出更高的质量归一化ORR塔菲尔活性（0.9 V时为0.303 A mg）、起始（1.06 V）和半波（0.78 V）电位以及更高的极限电流密度保留率（>88%），这归因于其独特的类蠕虫形态以及具有表面活性纳米岛且无载体的特性，从而实现了更好的催化剂利用率。在完全“非铂族金属AAEMFC”（n-PAAEMFC）中，与S-AgNs（41.3 mW cm）和先前报道的完全n-PAAEMFC相比，V-AgNs表现出最高的燃料电池活性，为115.6 mW cm，且具有稳定的短期耐久性（约240小时），表明它们在下一代碱性燃料电池中的潜在应用。
