Colloidal Cobalt Phosphide Nanocrystals as Trifunctional Electrocatalysts for Overall Water Splitting Powered by a Zinc–Air Battery. Issue 9 (15th January 2018)

• Record Type: Journal Article
• Authors: Li, Hui; Li, Qi; Wen, Peng; Williams, Trey B.; Adhikari, Shiba; Dun, Chaochao; Lu, Chang; Itanze, Dominique; Jiang, Lin; Carroll, David L.; Donati, George L.; Lundin, Pamela M.; Qiu, Yejun; Geyer, Scott M.
• Is Part Of: Advanced materials. Volume 30:Issue 9(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-01-15
• Subjects: cobalt phosphide -- density functional theory -- overall water splitting -- trifunctional electrocatalysts -- zinc–air batteries; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201705796
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this work, highly monodisperse CoP and Co2 P nanocrystals (NCs) are synthesized using a robust solution‐phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal‐rich Co2 P NCs show higher OER performance owing to easier formation of plentiful Co2 P@COOH heterojunctions. Density functional theory calculation results indicate that the desorption of OH* from cobalt sites is the rate‐limiting step for both CoP and Co2 P in ORR and that the high content of phosphide can lower the reaction barrier. A water electrolyzer constructed with a CoP NC cathode and a Co2 P NC anode can achieve a current density of 10 mA cm −2 at 1.56 V, comparable even to the noble metal‐based Pt/C and RuO2 /C pair. Furthermore, the CoP NCs are employed as an air cathode in a primary zinc–air battery, exhibiting a high power density of 62 mW cm −2 and good stability. Abstract : Monodisperse cobalt phosphide (CoP and Co2 P) nanocrystals are used as trifunctional catalysts toward oxygen reduction, hydrogen evolution, and oxygen evolution in alkaline electrolyte. A full alkaline electrolyzer composed of a CoP cathode and Co2 P anode can achieve 10 mA cm 2 at a voltage of 1.56 V for overall water splitting, which rivals the integrated state‐of‐the‐art Pt/C and RuO2 /C.