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

Abstract

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.

Co/CoP Nanoparticles Encapsulated Within N, P-Doped Carbon Nanotubes on Nanoporous Metal-Organic Framework Nanosheets for Oxygen Reduction and Oxygen Evolution Reactions

“…Due to the novel characteristics of CoP, its application in battery electrocatalysis and photocatalysis has received extensive attention. It provides a large number of active sites for electrochemical reaction to promote electrocatalytic activity [33]. CoP not only solves the problems of insufficient reserves, high price, and poor stability of Ru and Ir electrocatalysts, but also has good catalytic performance for OER [34,35].…”

Electrochemical Energy Conversion and Storage with Zeolitic Imidazolate Framework Derived Materials: A Perspective

“…Ganesan et al. followed a similar synthetic strategy to prepare CoP@N‐CNT by initial carbonization at 450 °C followed by the phosphidation . Synergistic coupling between N‐doped CNTs and CoP NPs offered a larger number of electro‐active sites with better diffusion kinetics and charge transportation channels for superior HER performance.…”

Cobalt Phosphide Ultrathin and Freestanding Sheets Prepared through Microwave Chemical Vapor Deposition: A Highly Efficient Oxygen Evolution Reaction Catalyst

“…[26] Recently, various polymorphs of cobalt phosphide have been extensively investigated as promising hydrogen evolution reaction (HER) electrocatalysts in alkaline, neutral and acidic solutions. [27][28][29][30][31][32][33][34][35] Meanwhile, limited number of nanostructured cobalt phosphide-based electrocatalysts, such as CoP nanorods, [36] CoP nanosheets/C, [37] CoP nanosheets, [22] CoP polyhedrons, [38] Phosphate modified CoP nanorods, [39] CoP/CoP 2 nanoparticles, [40] hollow CoP nanoparticles/N doped graphene, [41] Ni 1-x Co x P yolk-shell spheres, [42] etc. have been demonstrated to possess a satisfying OER activity in alkaline solution.…”

“…Particularly, phosphorus (P) exhibits a weaker electronegativity than that of oxygen, nitrogen, and sulfur, and it can assist the in situ formation of oxides/hydroxides and phosphates active centers on the catalyst surface for superior OER performances . Recently, various polymorphs of cobalt phosphide have been extensively investigated as promising hydrogen evolution reaction (HER) electrocatalysts in alkaline, neutral and acidic solutions . Meanwhile, limited number of nanostructured cobalt phosphide‐based electrocatalysts, such as CoP nanorods, CoP nanosheets/C, CoP nanosheets, CoP polyhedrons, Phosphate modified CoP nanorods, CoP/CoP 2 nanoparticles, hollow CoP nanoparticles/N doped graphene, Ni 1‐x Co x P yolk‐shell spheres, etc.…”