2, 2′-bipyridine palladium (II) complexes derived N-doped carbon encapsulated palladium nanoparticles for formic acid oxidation. (1st May 2022)

• Record Type: Journal Article
• Authors: Gao, Sijie; Hu, Shuozhen; Luo, Guoming; Sun, Shigang; Zhang, Xinsheng
• Is Part Of: Electrochimica acta. Volume 413(2022)
• Publication Date: 2022-05-01
• Subjects: 2, 2′-bipyridine palladium (II) complexes -- Pyrolysis -- N-doped carbon encapsulation -- Electronic effect -- Formic acid electro-oxidation; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.140179
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: In-situ pyrolysis is used to dope N in carbon matrix and reduce Pd 2+ simultaneously. Core-shell structured N-doped carbon encapsulated Pd nanoparticles are synthesized. Pd is reduced from Pd 2+ by the complexed N in 2, 2′-bipyridine during the pyrolysis. Pd-N complexes and charge transfer from carbon layer to Pd are observed in Pd@Nx C. In-situ pyrolysis method can be applied to carbon supports with different geometry. Abstract: Doping nitrogen (N) into the carbon support was widely applied to enhance the performance of Pd toward formic acid electro-oxidation (FAO). However, traditional nitrogen doping methods can only introduce a low content of nitrogen as well as a two-step complicated procedure to synthesize catalysts. In this study, a facile one-pot strategy is demonstrated to prepare N-doped carbon encapsulated palladium nanoparticles (Pd@Nx C) via the pyrolysis of 2, 2′-bipyridine palladium (II) complexes. A N-doped carbon layer with the thickness of about 4 nm is in-situ generated over Pd nanoparticles by only one pyrolysis procedure. Both XPS and in-situ XRD results suggest that metallic Pd is reduced from Pd 2+ by the complexed N in bipyridine during the pyrolysis at high temperature. The physical characterizations prove that the in-situ formation of N-doped carbon shell can not only effectively prevent the agglomeration or dissolution of Pd nanoparticles, but also promote the charge donation from the carbon layer to Pd, and maintain the structure of Pd atom complexed to two pyridinic-N atoms (Pd-N). This in-situ synthesis strategy can be successfully applied to carbon supports with different geometry, such as reduced graphene oxide and Vulcan XC-72. Pd@N3 C/rGO, which contains the highest amount of N (7.39 at.%) and Pd-N (33.15%), shows the highest specific activity (5.88 mA cm −2 ) and excellent durability toward FAO. Graphical abstract: Image, graphical abstract