Selective Oxygen Reduction to Hydrogen Peroxide Using Earth-Abundant Metal Pyrites As High-Performance Electrocatalysts

It is important to develop alternative catalysts made of inexpensive and earth-abundant elements with high catalytic activity and stability to replace the noble metal catalysts in various environmental¹ and renewable energy applications.² Here we report earth-abundant metal pyrites MS₂ (M as Fe, Ni, and Co) as high performance electrocatalysts^3,4 for oxygen reduction reaction (ORR) that is selective for generating hydrogen peroxide. In neutral solution of 0.1 M sodium perchlorate and acidic solution of 0.1 M perchloric acid, all three MS₂ show high ORR catalytic activity with excellent Tafel slopes. Based on Koutecky-Levich (K-L) analysis, all MS₂ and noble metal show similar potential-dependent selectivity of the two-electron peroxide pathway in neutral condition, and CoS₂ is the best among metal pyrites in terms of the positive potential for 50% H₂O₂selectivity. The stability of metal pyrites is quite good in under ORR operation in both neutral and acidic solutions. These inexpensive metal pyrites are excellent ORR catalysts for selective peroxide generation and could find promising applications in environmental and renewable energy technologies.

1. X.-W. Liu; W.-W. Li; H.-Q. Yu; “Cathodic catalysts in bioelectrochemical systems for energy recovery from wastewater” Chem. Soc. Rev., 2014, 43, 7718-7745.

2. Matthew S. F.; Song Jin;  “Earth-abundant inorganic electrocatalysts and their nanostructures for energy conversion applications” Energy Environ. Sci., 2014, 7, 3519-3542.

3. Matthew S. F.; Mark A. L.; Qi Ding; Nicolas S. K.; Song Jin; “Earth-Abundant Metal Pyrites (FeS₂, CoS₂, NiS₂, and Their Alloys) for Highly Efficient Hydrogen Evolution and Polysulfide Reduction” J. Phys. Chem. C, 2014, 118 (37), 21347-21356.

4. Matthew S. F.; Rafal D.; Mark A. L.; Nicholas S. K.; Qi Ding; Song Jin; “High-Performance Electrocatalysis Using Metallic Cobalt Pyrite (CoS₂) Micro- and Nanostructures” J. Am. Chem. Soc., 2014, 136 (28), 10053-100061.