Laboratoire de Réactivité et Chimie des Solides (LRCS), CNRS UMR 7314 , Université de Picardie Jules Verne , 33 Rue Saint Leu , 80039 Amiens Cedex , France.
Loker Hydrocarbon Research Institute, Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States.
ACS Appl Mater Interfaces. 2019 Sep 18;11(37):33811-33818. doi: 10.1021/acsami.9b09090. Epub 2019 Sep 3.
Noble-metal-free bifunctional electrocatalysts are indispensable to realize low-cost and energy-efficient rechargeable metal-air batteries. In addition, power density, energy density, and cycle life of these metal-air batteries can be improved further by utilizing the fast faradaic reactions of metal ions in the catalyst layer together with the oxygen evolution/reduction reactions (OER/ORR) for charge storage. In this work, we propose mixed metal phosphates of nickel and cobalt, NiCo(PO) ( = 0,1, 1.5, 2, and 3), as multifunctional air-cathodes exhibiting bifunctional electrocatalytic activity and reversible metal redox reaction (M, M = Ni and Co). Submicron-sized NiCo(PO) particles were synthesized by a solution combustion synthesis technique with urea acting as the fuel. Electrocatalytic activity toward the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in 0.1 M NaOH was systematically tuned by varying the Ni-to-Co ratio. The synthesized NiCo(PO) with = 1.5 (NCP11) showed superior bifunctional catalytic activity to other samples. Moreover, the catalyst material delivered a specific capacity of ∼110 mAh g by the redox reactions of its metal sites. The hybrid Na-air battery fabricated using the NCP11 catalyst-loaded air-cathode exhibited low overpotential, stable cycling performance, and round-trip energy efficiency exceeding 78% in a 0.1 M NaOH aqueous electrolyte.
无贵金属双功能电催化剂对于实现低成本、高能效的可再充电金属空气电池是不可或缺的。此外，通过利用催化剂层中金属离子的快速法拉第反应以及用于电荷存储的氧气析出/还原反应（OER/ORR），可以进一步提高这些金属空气电池的功率密度、能量密度和循环寿命。在这项工作中，我们提出了镍和钴的混合金属磷酸盐 NiCo(PO)（ = 0、1、1.5、2 和 3）作为多功能空气阴极，具有双功能电催化活性和可逆的金属氧化还原反应（M，M = Ni 和 Co）。通过使用尿素作为燃料的溶液燃烧合成技术合成了亚微米尺寸的 NiCo(PO) 颗粒。通过改变 Ni 与 Co 的比例，系统地调节了对氧气析出反应（OER）和氧气还原反应（ORR）的电催化活性。合成的 NiCo(PO)， = 1.5（NCP11）显示出比其他样品更好的双功能催化活性。此外，该催化剂材料通过其金属位点的氧化还原反应提供了约 110 mAh g 的比容量。在 0.1 M NaOH 水性电解质中，使用负载有 NCP11 催化剂的空气阴极制备的混合 Na-空气电池表现出低过电势、稳定的循环性能和超过 78%的往返能量效率。
