LaCoO₃ Perovskite Nanoparticles Embedded in NiCo₂O₄ Nanoflowers as Electrocatalysts for Oxygen Evolution

Abstract

It is essential to design high-efficiency, stable, and inexpensive electrocatalysts for the oxygen evolution reaction (OER). We fabricate a hybrid system of perovskite LaCoO 3 with spinel NiCo 2 O 4 denoted LaCoO 3 /NiCo 2 O 4 via an in situ hydrothermal process. In situ incorporation of LaCoO 3 nanoparticles on the NiCo 2 O 4 nanoflower surface is confirmed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images. Benefiting from the interface engineering, the obtained LaCoO 3 / NiCo 2 O 4 hybrid nanoflowers exhibit the lowest overpotential of 353 at a current density of 10 mA/cm 2 and a small Tafel slope of 59 mV/dec in alkaline media compared with pristine LaCoO 3 (401 mV, 116 mV/dec) and NiCo 2 O 4 (386 mV, 73 mV/dec). The optimized sample possesses a higher electrochemical surface of 111.45 cm 2 than LaCoO 3 perovskite (35.37 cm 2 ) and NiCo 2 O 4 spinel oxide (61.37 cm 2 ) structures. The enhanced OER performance of the LaCoO 3 /NiCo 2 O 4 composite structure is due to the accumulation of LaCoO 3 nanoparticles over NiCo 2 O 4 petals, which introduces a substantial number of electrochemically active sites for the catalysis process to promote charge and mass transport. In addition to this, LaCoO 3 / NiCo 2 O 4 exhibits long-term stability over 20 h. Thus, it is believed that the excellent OER activity of the LaCoO 3 /NiCo 2 O 4 composite structure is associated with strong interaction between LaCoO 3 and NiCo 2 O 4 as well as a large surface area and a unique flower structure.

Synergetic Nanostructure Engineering and Electronic Modulation of a 3D Hollow Heterostructured NiCo2O4@NiFe-LDH Self-Supporting Electrode for Rechargeable Zn–Air Batteries

“…Electrochemical impedance spectroscopy (EIS) was taken over a frequency range from 0.01 to 100 kHz at an amplitude of 5 mV, with a potential of 1.5 V vs RHE. The electrochemically accessible surface area (ECSA) was measured by obtaining cyclic voltammetry (CV) curves in the non-Faradaic region at different scan rates (20,40,60,80, and 100 mV s −1 ), while the linear slope values obtained by plotting the capacitive current density versus scan rate correspond to the electrochemical double-layer capacitance (C dl ). The ECSA was then determined by the equation: ECSA = C dl /C s , where C s was typically taken to be 0.04 mF cm −2 for nickel-based catalysts.…”

“…13,14 Especially, the spinel-structured transition-metal oxide of NiCo 2 O 4 has been demonstrated to possess high theoretical catalytic activity and good electronic conductivity and is comparable to noblemetal-based electrocatalyst benchmarks. 15 nanospheres, 16 nanopolyhedrons, 15 nanowires, 17 nanorods, 18 nanosheets, 19 nanoflowers, 20 and nanoribbons 21 have been elaborately designed to boost the OER process. It is indicated that nanostructure engineering is an effective strategy to optimize the OER properties of the NiCo 2 O 4 catalyst.…”

“…Over the past few years, considerable attention has been paid to transition-metal-based electrocatalysts because of their cheap price, extensive resource, environmental friendliness, and resistance to corrosion in alkaline solutions. , Especially, the spinel-structured transition-metal oxide of NiCo 2 O 4 has been demonstrated to possess high theoretical catalytic activity and good electronic conductivity and is comparable to noble-metal-based electrocatalyst benchmarks . So far, a variety of NiCo 2 O 4 materials with specific nanostructures including nanospheres, nanopolyhedrons, nanowires, nanorods, nanosheets, nanoflowers, and nanoribbons have been elaborately designed to boost the OER process. It is indicated that nanostructure engineering is an effective strategy to optimize the OER properties of the NiCo 2 O 4 catalyst .…”

NiS/MoS2 Anchored Multiwall Carbon Nanotube Electrocatalyst for Hydrogen Generation and Energy Storage Applications

“…Hence, the association of appropriate functional inorganic compounds is an effective approach to modulate the structural motif as well as the desired capabilities owing to the particular virtues of the inorganic compounds that are mainly incorporated into the solids structure and acting as an efficient materials energy generation and storage applications. [1,2] The exploration of low-cost and efficient bifunctional electrocatalysts for the OER, [3,4] hydrogen evolution reaction (HER), [5,6] and supercapacitors offer promising opportunities for sustainable energy sources due to the rapid depletion of fossil fuels. Promising renewable energy technolo-gies such as electrocatalytic water splitting has attracted considerable attention from researchers in recent years to find a possible solution to generate stable and sustainable clean hydrogen fuels, but the most effective state-of-the-art catalysts are noble metals such as Pt, IrO 2 , and RuO 2 in OER and HER, which are expensive and scarce, thereby extremely limiting their practical uses.…”

Access to carbon nanofiber composite hydrated cobalt phosphate nanostructure as an efficient catalyst for the hydrogen evolution reaction

“…In addition, cobalt-based electrocatalysts (CoP, Co 3 O 4 , CoOOH, CoSe 2 , etc.) have attracted significant attention for a variety of applications, including sensors (Hu et al, 2021b;Sari et al, 2022), supercapacitors (Rovetta et al, 2017;Li et al, 2018), lithium-ion batteries (Khan et al, 2016), and OER (Sun et al, 2021;Kubba et al, 2022). Because of their strong electrochemical activity, cobalt phosphates have attracted much attention in recent decades and have been used extensively in electrochemical energy storage and as electrocatalysts for water splitting (Shu et al, 2018;Majhi and Yadav, 2021a).…”