Insight on the active sites of CoNi alloy embedded in N-doped carbon nanotubes for oxygen reduction reaction

Abstract

Transition metal alloy electrocatalysts have sparked intense interest for their use in oxygen reduction reaction (ORR). However, there is almost no corresponding research on the alloy active sites. In this study, CoNi alloy nanoparticles embedded in bamboo-like N-doped carbon nanotubes (CoNi-NCTs) as catalysts constructed by a facile pyrolysis of Prussian blue analogs were investigated. The density functional theory calculation reveals that the oxygen molecules are more easily adsorbed on the Ni sites in these catalysts, while the Co sites favor the formation of OOH* intermediates during ORR. In addition, the cooperation of the CoNi alloys with the N-doped carbon benefits electron transfer and promotes electrocatalytic activity. The optimized CoNi-NCT shows remarkable ORR catalytic activity with an half-wave potential (E 1/2 ) of 0.83 V, an onset potential (E onset ) of 0.97 V, and superior durability, all of which surpass the commercial Pt/C catalysts. The assembled zinc-air battery delivers a small charge/discharge voltage gap of 0.86 V at 10 mA cm −2 , a high-power density of 167 mW cm −2, and good stability (running stably over 900 cycles).

The Fe3C–Nx Site Assists the Fe–Nx Site to Promote Activity of the Fe–N–C Electrocatalyst for Oxygen Reduction Reaction

“…However, it still suffers from the drawbacks of low reserves, high cost, and poor stability . So the urgent task is to explore excellent nonprecious metal catalysts for substituting precious metal catalysts. , Considerable recent works have been devoted to transition metal nitrides, carbides, alloy, and heteroatom-doped carbon materials. − Alternatively, introduced transition metals (such as Fe, Co, Ni) and nitrogen in carbon materials (M–N–C), especially for Fe/Fe 3 C-based Fe–N–C structures, have displayed significant activity and stability and gained increasing attention.…”

Ultrauniformly Dispersed Cu Nanoparticles Embedded in N-Doped Carbon as a Robust Oxygen Electrocatalyst

“…1−5 Currently, conventional nanosized platinumbased catalysts are widely used to lower the activation energy of ORR, but their high cost impedes the large-scale commercial application of the renewable energy devices. 6,7 Therefore, developing high-efficient and cost-effective nonprecious metalbased catalysts, such as N-doped carbons loaded with transition metals (M/C-N, M = Fe, Co, Cu, etc. ), to replace Pt-based precious metals is essential but still challenging.…”

“…Commercialization of clean and renewable energy conversion technologies, e.g., polymer electrolyte membrane fuel cells (PEMFCs) and metal–air batteries, relies greatly on highly efficient and durable oxygen reduction reaction (ORR) catalysts. − Currently, conventional nanosized platinum-based catalysts are widely used to lower the activation energy of ORR, but their high cost impedes the large-scale commercial application of the renewable energy devices. , Therefore, developing high-efficient and cost-effective nonprecious metal-based catalysts, such as N-doped carbons loaded with transition metals (M/C-N, M = Fe, Co, Cu, etc. ), to replace Pt-based precious metals is essential but still challenging. − …”

Pt–Ni Alloy Nanoparticles via High-Temperature Shock as Efficient Electrocatalysts in the Oxygen Reduction Reaction

“…8−10 Actually, great efforts have been made to develop nonprecious metals considering their low costs as well as abundance. 11,12 However, because of the poor activity and stability of nonprecious metals, 13,14 it turns out to be more feasible to integrate them with precious ones. 15−21 Because of the slow oxygen reduction reaction (ORR) kinetics, the development of cathode catalysts remains a critical step in alkaline FCs.…”

“…With the rapid depletion of fossil fuels and increasing demand for clean energy, research on fuel cells and other renewable energy technologies has seen strong growth in the past few years. − The recent advances in anion exchange membranes have provided new opportunities for alkaline fuel cells (FCs). − Actually, great efforts have been made to develop nonprecious metals considering their low costs as well as abundance. , However, because of the poor activity and stability of nonprecious metals, , it turns out to be more feasible to integrate them with precious ones. − …”