Gond Ritambhara, Singh Shashwat, Zhao Xiaofeng, Singh Deobrat, Ahuja Rajeev, Fichtner Maximilian, Barpanda Prabeer
Faraday Materials Laboratory (FaMaL), Materials Research Centre, Indian Institute of Science, Bangalore 560012, India.
Department of Chemistry, Ångström Laboratory, Uppsala University, Box 516, 75120 Uppsala, Sweden.
ACS Appl Mater Interfaces. 2022 Sep 14;14(36):40761-40770. doi: 10.1021/acsami.2c06944. Epub 2022 Sep 6.
Developing earth-abundant low-cost bifunctional oxygen electrocatalysts is a key approach to realizing efficient energy storage and conversion. By exploring Co-based sodium battery materials, here we have unveiled nanostructured pyrophosphate NaCoPO polymorphs displaying efficient bifunctional electrocatalytic activity. While the orthorhombic polymorph (-NCPy) has superior oxygen evolution reaction (OER) activity, the triclinic polymorph (-NCPy) delivers better oxygen reduction reaction (ORR) activity. Simply by tuning the annealing condition, these pyrophosphate polymorphs can be easily prepared at temperatures as low as 500 °C. The electrocatalytic activity is rooted in the Co redox center with the (100) active surface and stable structural framework as per calculations. It marks the first case of phospho-anionic systems with both polymorphs showing stable bifunctional activity with low combined overpotential (ca. ∼0.7 V) comparable to that of reported state-of-the-art catalysts. These nanoscale cobalt pyrophosphates can be implemented in rechargeable zinc-air batteries.
开发地球上储量丰富的低成本双功能氧电催化剂是实现高效能量存储和转换的关键途径。通过探索钴基钠电池材料，我们在此揭示了具有高效双功能电催化活性的纳米结构焦磷酸钠钴多晶型物。正交多晶型物（-NCPy）具有优异的析氧反应（OER）活性，而三斜多晶型物（-NCPy）具有更好的氧还原反应（ORR）活性。只需调节退火条件，这些焦磷酸多晶型物就能在低至500°C的温度下轻松制备。根据计算，电催化活性源于具有（100）活性表面和稳定结构框架的钴氧化还原中心。这标志着磷阴离子体系首次出现两种多晶型物均表现出稳定的双功能活性，且具有与已报道的先进催化剂相当的低综合过电位（约0.7V）。这些纳米级钴焦磷酸盐可用于可充电锌空气电池。
