Highly Effective Electrochemical Water Oxidation by Millerite-Phased Nickel Sulfide Nanoflakes Fabricated on Ni Foam by Aerosol-Assisted Chemical Vapor Deposition

Abstract

Fabrication of effective and low-cost electrocatalysts for water splitting is critical to sustainable energy-conversion technologies. We report the synthesis of nickel sulfide (NiS) nanoflakes by aerosol-assisted chemical vapor deposition (AACVD) on Ni foam. Upon electrochemical measurements, NiS nanoflake films exhibit excellent oxygen evolution reaction (OER) activity and stability in basic solutions, advancing an attractive alternative to precious metals and other transition-metal catalysts that have been extensively investigated. The NiS@Ni-Foam prepared at 350 °C offered a high current density of 1100 mA/cm2 at an overpotential of 450 mV with a Tafel slope of 81.3 mV/dec. Furthermore, it remained durable at a constant current for >15 h in 1 M KOH solution. The high OER activity of NiS@Ni-Foam prepared at 350 °C is due to the nanoflake-like morphology and crystalline structure, as observed under scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). Likewise, NiS@Ni-Foam prepared at 350 °C provided a high specific surface area for facile ion transport, charge transfer, and enormous electrochemical active sites. Hence, it collectively resulted in enhanced water splitting oxygen evolution reaction (OER).

Direct Fabrication of Nanoscale NiVOx Electrocatalysts over Nickel Foam for a High-Performance Oxygen Evolution Reaction

“…Positive potentiostatic treatments electrochemically convert metal oxides into the electrochemically active component with high chemical valence, such as metal hydroxide/oxyhydroxide species, which are responsible for efficient water oxidation. , Following that, the electrode films including NiVO x /NF 60 , NiVO x /NF 120 , and NiVO x /NF 180 are tested as working electrodes for water oxidation studies. OER performance is primarily characterized via linear sweep voltammetry (LSV) measurements under a three-electrode cell configuration in a 1.0 M aq.…”

“…The nickel foam substrate was decorated with electrocatalytically active mixed-metal nickel vanadium oxide (NiVO x ) films by adopting our previous aerosol-assisted chemical vapor deposition (AACVD) strategy . The operational details of AACVD have been elaborated on in our recent works. ,,, The precursors VO­(acac) 3 (100 mg, 0.4 mmol) and Ni­(acac) 2 (100 mg, 0.4 mmol) were simultaneously dissolved in 20 mL of methanol without using any solubilizing agent. The resulting sea-green solution obtained after 10 min of stirring was directly employed as a precursor feedstock for thin-film deposition.…”

“…It is evident that the noble metal catalysts (Ir/Ru oxides) excel in accelerating the OER since they require a low potential input and can work well in acidic as well as alkaline pH conditions. Nonetheless, their high price and scarcity are the major hurdles to advancing their water splitting applications. , Consequently, the designing of inexpensive and earth-rich catalysts with high stability and excellent OER activity is the primary goal to implement water splitting on an industrial level. , In this regard, an enormous and fascinating range of electrocatalyst materials including inexpensive and widespread transition-metal-based monometals and binary metal alloys/oxides, metal nitrides, transition-metal chalcogenides, metal phosphides, and metal-free carbon materials with exceptional water splitting efficiencies have been reported extensively. However, for economic viability, despite all those advancements, some competent and modest electrocatalytic systems, obtainable by straightforward methods, and inexpensive precursors with high electroactive sites and enhanced catalytic activity still need to be disclosed. , …”

Electrocatalytic Investigations into a PdNi Nanostructured Alloy Supported over a Graphite Sheet toward Pt-like Hydrogen Evolution Activity

“…It produces high-purity hydrogen without any carbon emissions. The process of electrochemical water splitting is accomplished in two reaction steps, which are designated as the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), and HER is a key reaction for the production of hydrogen . At present, hydrogen production using electrolysis is not economically viable due to high energy consumption and low hydrogen production .…”

“…The process of electrochemical water splitting is accomplished in two reaction steps, which are designated as the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), and HER is a key reaction for the production of hydrogen. 15 At present, hydrogen production using electrolysis is not economically viable due to high energy consumption and low hydrogen production. 16 To be economically competitive, it is desired to complete these reactions at faster rates with highly efficient and durable electrocatalysts.…”