Surface Reconstruction of an FeNi Foam Substrate for Efficient Oxygen Evolution

Abstract

Designing earth-abundant electrocatalysts that are highly active, low-cost, and stable for the oxygen evolution reaction (OER) is crucial for electrochemical water splitting. However, in conventional electrode fabrication strategies, NiFe layered double hydroxide (NiFe LDH) catalysts are usually coated onto substrates as external components, which suffers from poor conductivity, easily detaches from the substrate, and hinders their long-term utilization. Herein, the surface-reconstruction strategy is used to synthesize in situ autologous NiFe LDH to increase the surficial active sites numbers. The FeNi foam (FNF) serves as both the metal source and substrate, and the obtained NiFe LDH nanosheets (NSs) are firmly anchored in the monolithic FNF. What needs to be emphasized is that the strategy does not involve any high-temperature or high-pressure processes, apart from a cost-effective etching and a specified drying treatment. The nanostructure of NiFe LDH and the synergistic effect between Fe and Ni simultaneously lead to an enhanced catalytic effect for the OER. Remarkably, the sr-FNF46 requires only an ultralow overpotential of 283 mV to achieve a current density of 100 mA cm −2 for the OER in 1 M KOH electrolyte, and exhibits excellent stability. Thus, the obtained electrode holds promise for electrocatalytic applications. Finally, the formation mechanism of NiFe LDH NSs due to surface reconstruction is investigated and discussed in detail.

Facile method to activate substrate for oxygen evolution by a galvanic-cell reaction

“…Another two peaks at 711.6 and 724.3 eV belong to Fe 2p 3/2 and Fe 2p 1/2 for Fe 3+ , respectively. 7 These results suggest the presence of trivalent Fe species. The Cl 2p spectrum (Fig.…”

“…Transition-metal-based materials have been used to develop alternative catalysts. 6,7 Among transition-metal-based electrocatalysts, Ni and Fe are earth-abundant elements and exhibit high performance in the catalysis of OER, which is beneficial for achieving an optimal interaction strength with OH ad and satisfies the Sabatier principle for catalyst design. [8][9][10] Moreover, it has been proved that Fe can modulate the electronic structure of Ni, which optimizes their adsorption energy and further enhances their electrocatalytic activities.…”

“…Finally, Fe 3+ , Ni 2+ , and OH À will react to form NiFe LDH (eqn ( 5)). In addition, FeOOH is formed according to eqn ( 6) and (7).…”

Rational Construction of a Triple-Phase Reaction Zone Using CuO-Based Heterostructure Nanoarrays for Enhanced Water Oxidation Reaction

“…3,4 Although RuO 2 and IrO 2 are highly active materials for the OER, their high price and unsatisfactory durability have restricted their utilization on a large scale. 5 Therefore, it is significant to develop alternative earth-abundant transitionmetal electrocatalysts that are cost-effective, having remarkable OER activity and stability, including Co-, Mn-, Cu-, and Nirelated oxides because of their inherently regulable geometric and electronic properties, and environmental friendliness. 5−8 To further boost OER performance for transition-metal oxides (TMOs), many researchers offered a variety of tactics (such as interface engineering, defect, dopant, or single-atom design) to enhance the intrinsic activity of catalytic sites through optimizing the adsorption free energy of key intermediates to expedite the rate-determined step in the entire reactions.…”

Heterostructure Interface Engineering in CoP/FeP/CeOx with a Tailored d-Band Center for Promising Overall Water Splitting Electrocatalysis

“…The significant threat of energy crisis and environmental issues caused by fossil fuel combustion necessitates researchers to explore alternative energy sources, in which hydrogen (H 2 ) is deemed to be a futuristic renewable energy vector due to its high gravimetric energy density (142 MJ kg –1 ) and unpolluted products. − It also requires zero-carbon emission technology during its production process, achieving a carbon-neutral society. Electrochemical water splitting driven by electricity conversion from intermittent energy sources (wind or solar) has been regarded as a promising technology for green hydrogen production, playing a vital role in the hydrogen economy. , Unfortunately, this intriguing technology is hampered by its low energy efficiency and diminished by the sluggish kinetics of the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER) .…”