Construction of CoP/Co₂P Coexisting Bifunctional Self-Supporting Electrocatalysts for High-Efficiency Oxygen Evolution and Hydrogen Evolution

Abstract

Development of a low cost, high activity, and stable nonprecious metal bifunctional catalyst for electrocatalytic water cracking is a hot topic and big challenge. In this paper, we prepared a nitrogen-doped carbon nanotube (NCNT)-enhanced three-dimensional self-supported electrocatalyst with CoP and Co 2 P coexistence by a two-step strategy of high-temperature carbonization and low-temperature phosphorylation. Furthermore, the induced three-dimensional carbon network skeleton facilitates rapid charge transfer. In addition, the active sites of the carbon foam (CF) are greatly increased by the construction of hollow structures. As a bifunctional electrocatalyst, CoP/Co 2 P/NCNT@CF exhibited excellent catalytic activity for both hydrogen evolution reaction and oxygen evolution reaction in alkaline media, requiring low overpotentials of 133 and 289 mV to obtain a current density of 10 mA cm –2 , respectively. Additionally, the synthesized catalysts also exhibit good long-term stability, maintaining high catalytic activity after 20 h of continuous operation. We also confirmed the main driving force to improve the electron transfer between the heterostructures of Co and P by XPS spectra. The excellent electrocatalytic performance can be attributed to the close synergy between the highly active CoP/Co 2 P/NCNT and CF. This study provides a new strategy for the design of highly active bifunctional self-supporting electrocatalysts.

Construction of Hollow Carbon Nanofibers with Graphene Nanorods as Nano-Antennas for Lower-Frequency Microwave Absorption

“…In the high-resolution Co 2p spectrum, two peaks located at 780.9 and 786.1 eV can be ascribed to Co 2p 3/2 and Co 2p 1/2 , which correspond to metallic Co (Figure e). , Two satellite peaks located at 796.2 and 802.6 eV can be assigned to Co–N x , which means that N doping can increase the defects and enhance polarization loss. , The N–Co peak at 399.75 eV in the high resolution of the N 1s spectrum also confirms the existence of N doping (Figure S9). The binding energy of the Co–N x peak shows a decreasing trend due to the strong electronic interaction between them. , With increasing annealing time, the content of Co–N also increases, which means that the N-doping effect is enhanced, resulting in more dipole polarization.…”

“…43 The binding energy of the Co−N x peak shows a decreasing trend due to the strong electronic interaction between them. 44,45 With increasing annealing time, the content of Co−N also increases, which means that the N-doping effect is enhanced, resulting in more dipole polarization.…”

A review on development of metal–organic framework-derived bifunctional electrocatalysts for oxygen electrodes in metal–air batteries

“…The developed catalysts also have exceptional long-term stability; they continue to have significant catalytic activity even after 20 hours of continuous operation. 88…”

Simple Method to Enhance the Oxidation–Reduction Reaction Activity of a Carbon Nanotube-Based Nickel–Iron Layered Double Hydroxide as a Bifunctional Electrocatalyst

“…Currently, the creation of alternative sustainable green energies with high performance is a strong social demand, which is one of the crucial targets in the SDGs action platforms, and promising alternative energy technologies are batteries, fuel cells, supercapacitors, and solar energy in addition to natural energy, such as wind power, geothermal power generation, etc. The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occur with very sluggish kinetics; − however, efficient and durable ORR/OER bifunctional electrocatalysts are very important for lowering the overpotentials to improve the energy conversion efficiency of industry-demanded rechargeable metal-air batteries and reversible fuel cells, water electrolyzers, and smart-grid energy storage systems for commercialization. Precious-metal-based catalysts, such as nanoparticles of Pt and IrO 2 , have been well known as excellent electrocatalysts for the ORR and OER, respectively .…”

“…Precious-metal-based catalysts, such as nanoparticles of Pt and IrO 2 , have been well known as excellent electrocatalysts for the ORR and OER, respectively . Considering the cost and source scarcity, however, the development of non-precious-metal catalysts from earth-abundant elements, such as iron (Fe), nickel (Ni), and/or Ti including transition-metal chalcogenides, oxides, nitrides, doped nanocarbon materials, metal macrocycles, etc., is in high demand from industry. − Many papers describing advances involving ORR and OER electrocatalysis mainly using non-precious-metal catalysts have been published. − …”