CoP Embedded in Hierarchical N‐Doped Carbon Nanotube Frameworks as Efficient Catalysts for the Hydrogen Evolution Reaction

• Published in: ChemElectroChem Vol. 5; no. 13; pp. 1644 - 1651
• Main Authors: Ganesan, Vinoth, Kim, Jinkwon, Radhakrishnan, S.
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 02.07.2018
• Subjects: Carbon; Carbon nanotubes; Carbonization; Catalysis; Catalysts; Chemical synthesis; Cobalt; cobalt phosphide; Electrocatalysts; electrochemistry; Energy conversion; Graphitization; hierarchical frameworks; hydrogen evolution reaction; Hydrogen evolution reactions; Nanoparticles; Nanotubes; Phosphides
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.201800381

Highly efficient, nonprecious and stable electrocatalysts for the hydrogen evolution reaction (HER) are absolutely crucial for renewable energy conversion, yet the design of such catalysts remains to be a long and arduous task. Herein, cobalt phosphide (CoP) nanoparticles (NPs) embedded in hierarchical N‐doped carbon nanotube frameworks (CoP‐HNCs) have been synthesized by controlled phosphidation of cobalt NPs embedded in hierarchical N‐doped carbon nanotube frameworks (Co‐HNCs). The Co‐HNCs were prepared by direct carbonization of Co‐based zeolitic imidazolate networks (ZIF‐67). Benefitting from multiple structural and compositional features, such as a multitude of catalytically active sites, a high degree of graphitization, and a thin carbon layer enclosing the NPs, CoP‐HNCs serve as a superior electrocatalyst towards the hydrogen evolution reaction. The synthesized CoP‐HNCs delivered a low overpotential at a current density of 10 mA cm−2 (η10) of 79 mV and 96 mV with small Tafel slope value of 45.6 mV dec−1 and 49.5 mV dec−1 in acidic and alkaline conditions, respectively. In addition, the catalyst showed long‐time durability under both acidic and alkaline electrolyte conditions, further demonstrating their potential to replace Pt‐based precious catalysts. Embedded hydrogen evolution: Cobalt phosphide nanoparticles embedded in N‐doped carbon nanotube frameworks are prepared as catalyst for the hydrogen evolution reaction. The formation of the material is systematically studied. In test reactions, the catalyst exhibits low overpotentials in acidic and alkaline media, while showing a high stability under these conditions, demonstrating its potential for an application in water splitting devices.