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

Abstract

Herein, Co/CoP nanoparticles encapsulated with N, P-doped carbon nanotubes derived from the atomic layer deposited hexagonal metal-organic frameworks (MOFs) are obtained by calcinations and subsequent phosphating and are employed as electrocatalyst. The electrocatalytic performance evaluations show that the as-prepared electrocatalyst exhibits an overpotential of 342 mV at current density of 10 mA cm −2 and the Tafel slope of 74 mV dec −1 for oxygen evolution reaction (OER), which is superior to the most advanced ruthenium oxide electrocatalyst. The electrocatalyst also shows better stability than the benchmark RuO 2. After 9 h, the current density is only decreased by 10%, which is far less than the loss of RuO 2. Moreover, its onset potential for oxygen reduction reaction (ORR) is 0.93 V and follows the ideal 4-electron approach. After the stability test, the current density of the electrocatalyst retains 94% of the initial value, which is better than Pt/C. The above results indicate that the electrocatalyst has bifunctional activity and excellent stability both for OER and ORR. It is believed that this strategy provides guidance for the synthesis of cobalt phosphide/carbon-based electrocatalysts.

Co/CoP Heterojunction on Hierarchically Ordered Porous Carbon as a Highly Efficient Electrocatalyst for Hydrogen and Oxygen Evolution

“…The Co-P peak in the high-resolution spectrum of P is very weak, possible due to the exposure to air that can be evidenced by the existence of P-O (134.7 eV) and P-C (133.8 eV) peaks (Figure 3f). [46,49,50] These results further confirm the successful formation of the Co/CoP nanoparticles in the 3DOM carbon skeleton.…”

“…In Figure 3e, the C1 s spectrum was divided into four peaks centered at 284.6, 285.2, 286.2, and 288.4 eV, which can be assigned to the C-C, C-P, C-O, and O-CO, respectively. [46][47][48] The high-resolution spectrum for P 2p shows two peaks at 130.8 and 129.6 eV that are ascribed to the binding energies of P 2p 1/2 and P 2p 3/2 , respectively. The Co-P peak in the high-resolution spectrum of P is very weak, possible due to the exposure to air that can be evidenced by the existence of P-O (134.7 eV) and P-C (133.8 eV) peaks (Figure 3f).…”

Integration of partially phosphatized bimetal centers into trifunctional catalyst for high-performance hydrogen production and flexible Zn-air battery

“…As for the OER activity, it comes partly from the P-doped carbon sites, i.e., ORR active sites, due to the reversibility of the ORR and OER pathways. Furthermore, the bulk metal phosphides and surface oxides also potentially contribute to the OER activity, as discussed in previous reports [47][48][49][50]. Thus, the OER performance of FeCo-P/PNC shows corrections with both P-doing and Fe/Co ratio in Fig.…”

In Situ Growth of Hollow Trimetallic Nanocubes on Nickel Foam for the Electrocatalytic Oxygen Evolution Reaction

“…The electrochemical surface area (ECSA), important for OER performance, is closely related to the electrochemical double‐layer capacitance (Cdl). The twice of Cdl is the plot obtained through ▵j (j a ‐j c ) fitting linearly with scan rates, where corresponding ▵j is received by the cyclic voltammetry (CV) test (Figure S3) at different scan rates in the non‐Faraday region [57–58] . As displayed in Figure 5e, the NiFeCo(4 : 1)PBA@NF‐350 offers the largest 2Cdl (0.03478 mF cm −2 ) value than NiFe‐PBA@NF‐350 (0.02985 mF cm −2 ), CoFe‐PBA@NF‐350 (0.02647 mF cm −2 ) NiCo‐PBA@NF‐350 (0.02325 mF cm −2 ) and NF‐350 (0.00902 mF cm −2 ), indicating that the NiFeCo(4 : 1)PBA@NF‐350 supplies higher ECSA toward OER.…”

“…The twice of Cdl is the plot obtained through~j (j a -j c ) fitting linearly with scan rates, where corresponding~j is received by the cyclic voltammetry (CV) test ( Figure S3) at different scan rates in the non-Faraday region. [57][58] As displayed in Figure 5e, the NiFeCo(4 : 1)PBA@NF-350 offers the largest 2Cdl (0.03478 mF cm À 2 ) value than NiFe-PBA@NF-350 (0.02985 mF cm À 2 ), CoFe-PBA@NF-350 (0.02647 mF cm À 2 ) NiCo-PBA@NF-350 (0.02325 mF cm À 2 ) and NF-350 (0.00902 mF cm À 2 ), indicating that the NiFeCo(4 : 1)PBA@NF-350 supplies higher ECSA toward OER. The above electrocatalytic OER results indicate that the electrocatalyst derived from the trimetallic Prussian blue analogues have better performance than the catalysts derived from bimetallic Prussian blue analogues (such as NiFe-PBA@NF-350, CoFe-PBA@NF-350, NiCo-PBA@NF-350).…”