Surface Reorganization on Electrochemically‐Induced Zn–Ni–Co Spinel Oxides for Enhanced Oxygen Electrocatalysis

Abstract

Herein, we highlight redox‐inert Zn2+ in spinel‐type oxide (ZnXNi1−XCo2O4) to synergistically optimize physical pore structure and increase the formation of active species on the catalyst surface. The presence of Zn2+ segregation has been identified experimentally and theoretically under oxygen‐evolving condition, the newly formed VZn−O−Co allows more suitable binding interaction between the active center Co and the oxygenated species, resulting in superior ORR performance. Moreover, a liquid flow Zn–air battery is constituted employing the structurally optimized Zn0.4Ni0.6Co2O4 nanoparticles supported on N‐doped carbon nanotube (ZNCO/NCNTs) as an efficient air cathode, which presents remarkable power density (109.1 mW cm−2), high open circuit potential (1.48 V vs. Zn), excellent durability, and high‐rate performance. This finding could elucidate the experimentally observed enhancement in the ORR activity of ZnXNi1−XCo2O4 oxides after the OER test.

Biaxial Stretchability in High‐Performance, All‐Solid‐State Supercapacitor with a Double‐Layer Anode and a Faradic Cathode Based on Graphitic‐2200 Knitted Carbon Fiber

“…Furthermore, the Ni 2p 3/2 and Ni 2p 1/2 spectra of MOF‐ZNCO@g‐KCF, centered at approximately 856.2 and 873.5 eV, have respectively been perfectly deconvoluted into two peaks each, indicating the presence of different coordination environments for the Ni species (Figure 3c). [ 29 ] Similarly, the deconvoluted peaks at approximately 862 and 880 eV represent the satellite peaks of the Ni 2p 3/2 and Ni 2p 1/2 peaks, respectively. Likewise, Figure 3d clearly reveals the existence of two perfectly deconvoluted peaks without any shake‐up satellites at approximately 1021 and 1044 eV, which are signatures of the Zn 2+ states for the Zn 2p 3/2 and Zn 2p 1/2 levels, respectively.…”

“…Likewise, Figure 3d clearly reveals the existence of two perfectly deconvoluted peaks without any shake‐up satellites at approximately 1021 and 1044 eV, which are signatures of the Zn 2+ states for the Zn 2p 3/2 and Zn 2p 1/2 levels, respectively. [ 29 ] As shown in Figure 3e, the C 1s spectrum is deconvoluted into three peaks centered at 284.8, 286.6, and 288.8 eV, representing the sp 2 (40.6%), sp 3 (31.2%) and OCO (28.2%) carbon species, respectively. [ 30 ] Figure 3f represents the high resolution spectrum of O 1s, deconvoluted into three prominent peaks at binding energies of 529.2, 531.6, and 533.8 eV.…”

Multifunctional WO3/NiCo2O4 heterojunction with extensively exposed bimetallic Ni/Co redox reaction sites for efficient photoelectrochemical water splitting

“…As a spinel type binary metal oxide and p-type semiconductor, NiCo 2 O 4 has been widely used in electrocatalysis with the properties of abundant reserves, excellent conductivity and low cost. [47,48] Furthermore, the abundant redox couples of Ni 2 + /Ni 3 + and Co 2 + /Co 3 + contained in NiCo 2 O 4 not only lead to higher electrical conductivity than NiO and Co 3 O 4 , [49][50][51] but also induce the potential of co-catalyst in the PEC water splitting. Unfortunately, the application of NiCo 2 O 4 in PEC water splitting is extremely rare, especially the investigation of WO 3 modified by NiCo 2 O 4 is seldom reported, so that the effect and mechanism of the p-type NiCo 2 O 4 with bimetallic reaction sites on WO 3 are not unequivocal.…”

Defect Electrocatalysts and Alkaline Electrolyte Membranes in Solid‐State Zinc–Air Batteries: Recent Advances, Challenges, and Future Perspectives

“…For instance, by engineering the composition of spinel oxides, their properties, such as crystalline and electronic structure, which play vital roles in ORR/OER catalysis, can be well tuned. [47][48][49][50] In addition, varying the composition of the hybrid nanocomposites (e.g., chemical attachment and electrical coupling between ORR-and OER-active materials) could be an efficient strategy to develop bifunctional electrocatalysts. [2,51,52] The particle size of the catalysts is also highly relevant to their catalytic activities.…”