Electrospun Thin-Walled CuCo₂O₄@C Nanotubes as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn–Air Batteries

Abstract

Rational design of optimal bifunctional oxygen electrocatalyst with low cost and high activity is greatly desired for realization of rechargeable Zn-air batteries. Herein, we fabricate mesoporous thin-walled CuCoO@C with abundant nitrogen-doped nanotubes via coaxial electrospinning technique. Benefiting from high catalytic activity of ultrasmall CuCoO particles, double active specific surface area of mesoporous nanotubes, and strong coupling with N-doped carbon matrix, the obtained CuCoO@C exhibits outstanding oxygen electrocatalytic activity and stability, in terms of a positive onset potential (0.951 V) for oxygen reduction reaction (ORR) and a low overpotential (327 mV at 10 mA cm) for oxygen evolution reaction (OER). Significantly, when used as cathode catalyst for Zn-air batteries, CuCoO@C also displays a low charge-discharge voltage gap (0.79 V at 10 mA cm) and a long cycling life (up to 160 cycles for 80 h). With desirable architecture and excellent electrocatalytic properties, the CuCoO@C is considered a promising electrocatalyst for Zn-air batteries.

CuCo2S4 Nanosheets@N‐Doped Carbon Nanofibers by Sulfurization at Room Temperature as Bifunctional Electrocatalysts in Flexible Quasi‐Solid‐State Zn–Air Batteries

“…[19,[38][39][40][41][42] With the incorporation of Cu, the CuCo-based electrocatalysts display a higher catalytic activity due to their tailored electron transfer between Cu and Co ions. [21] Moreover, due to the solubility constants (K sp ) of copper sulfide and cobalt sulfide are very low, 2.5 × 10 −48 and 4 × 10 −21 , respectively, CuCo 2 O 4 nanoparticles (NPs) have been successfully converted to CuCo 2 S 4 NSs driven by the thermodynamic equilibrium in the Na 2 S solution ( Figure S1c,d, Supporting Information). [21] Moreover, due to the solubility constants (K sp ) of copper sulfide and cobalt sulfide are very low, 2.5 × 10 −48 and 4 × 10 −21 , respectively, CuCo 2 O 4 nanoparticles (NPs) have been successfully converted to CuCo 2 S 4 NSs driven by the thermodynamic equilibrium in the Na 2 S solution ( Figure S1c,d, Supporting Information).…”

“…[1][2][3][4][5][6][7][8] In principle, the advancement of flexible ZABs is critically dependent on the availability of desired air electrodes with excellent bifunctional electrocatalysis for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), together with robust flexibility and mechanical strength. [19][20][21][22][23][24][25][26][27] For example, CuCo 2 O 4 quantum dots attached on N-doped carbon nanotubes (CuCo 2 O 4 @NCNTs) were shown to be an impressively bifunctional electrocatalyst including a good positive half-wave potential (0.80 V) for ORR and a low overpotential (467 mV@10 mA cm −2 ) for OER, which can contribute to an energy density of 659 W h kg −1 (in liquid state) for ZAB. Bimetallic oxides (BOs)@heteroatom-doped carbon hybrids have drawn considerable attentions, because of their high catalytic efficiency, derived from the synergetic effects between the nanostructured BOs (for OER) and N-doping in carbon materials (for ORR).…”

“…[9][10][11][12][13][14][15][16][17][18] For this purpose, several types of cathode materials have been explored. [23] Although great progress has been made recently with BOs@NC-based ZABs in liquid state, [19][20][21][22][23][24][25][26][27] the overall performances in quasi-solid-state are still far away from those key The performance of quasi-solid-state flexible zinc-air batteries (ZABs) is critically dependent on the advancement of air electrodes with outstanding bifunctional electrocatalysis for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), together with the desired mechanical flexibility and robustness. [19][20][21][22][23][24][25][26][27] For example, CuCo 2 O 4 quantum dots attached on N-doped carbon nanotubes (CuCo 2 O 4 @NCNTs) were shown to be an impressively bifunctional electrocatalyst including a good positive half-wave potential (0.80 V) for ORR and a low overpotential (467 mV@10 mA cm −2 ) for OER, which can contribute to an energy density of 659 W h kg −1 (in liquid state) for ZAB.…”

Electrospun Carbon Nanofibers Encapsulated with NiCoP: A Multifunctional Electrode for Supercapattery and Oxygen Reduction, Oxygen Evolution, and Hydrogen Evolution Reactions

“…The onset of hydrogen evolution was seen emerging at a low potential of −0.10 V (vs RHE) at a scan rate of 5 mV s −1 and a much less overpotential of 130 mV was required to drive a current density of 10 mA cm −2 for NiCoP/CNF900, which is comparatively lower than the reported Ni-and Co-based HER electrodes listed in Table 3. [12,13,23,29,30,[67][68][69][70][71] Inset of Figure 9e illustrates the required HER overpotential to achieve a current density of 10 mA cm −2 for the prepared electrocatalysts. Since long-term stability is a decisive criterion to evaluate the performance of the electrocatalyst, the CA analysis is studied for a constant potential of −0.28 V (vs RHE) for 20 h as shown in Figure 9e.…”

“…At present, platinum and ruthenium or iridiumbased noble metals are employed as an efficient electrocatalyst for fuel cell and water electrolysis. [28] Li et al have presented a simple and scalable electrospinning strategy for the concurrent synthesis of CoFe 2 O 4 @N-CNFs, which demonstrated an efficient earth-abundant OER electrocatalyst with an overpotential of 349 mV to achieve a current density of 10 mA cm −2 with a small Tafel slope and long-term durability in alkaline solution. [24] Hence, replacing these noble metals by a non-noble metal-based electrocatalysts, unfaltering the performance is the dynamic task of the present scenario.…”