Natural clay magadiite containing silicon (Si) was heated in a sealed container in a water-based solution containing iron chloride (FeCl3) and nickel chloride (NiCl2) to create a metal silicate composed of nickel (Ni), iron (Fe), and Si. The metal silicate was then reduced by adding electrons to the metal silicate atoms with magnesium, salt, and heat to create the more organized intermetallic silicide (ferric-nickel silicide) structure. The graph illustrates the lower voltage required for the ferric-nickel silicide (FeNiSi) alloy electrocatalyst to produce hydrogen and oxygen gas compared to NiSi and FeSi alloys. Credit: Nano Research Energy, Tsinghua University Press
A new electrocatalyst composed of nickel (Ni), iron (Fe) and silicon (Si) that reduces the amount of energy needed to synthesize H2 from water was manufactured in a simple and economical way, thus increasing the practicality of H2 as a clean and renewable energy of the future.
Hydrogen is a highly combustible gas that can help the world meet its clean energy goals if manufactured in an environmentally friendly way. The main obstacle to creating hydrogen gas from water is the large amount of energy required for water electrolysis, or the splitting of water molecules into hydrogen gas (H2) and oxygen (O2).
Most H2 produced today is derived from fossil fuels, which contributes to global warming. Manufacturing H2 of water through the hydrogen evolution reaction (HER) requires the use of a catalyst or agent that reduces the amount of energy required for a chemical reaction. Until recently, these catalysts were made of rare earth metals, such as platinum, which reduced the profitability and practicality of producing clean hydrogen.
A group of materials scientists from Dalian University of Technology, China, have made an electrocatalyst, or catalyst that uses electricity, using inexpensive materials and methods to effectively reduce the energy required to generate clean H.2 some water. Importantly, the ferric-nickel silicide (FeNiSi) alloy or mixture also reduces the energy required to generate O.2 from water, making the catalyst bifunctional.
The researchers published their study in Nano research energy.
“What really limits the development and practical application of water electrolysis technology is electrocatalytic materials. At present, common catalysts, such as precious metals… are mostly single-function catalysts, which limits the practical application of water electrolysis for hydrogen production. “Research and development of efficient, stable, cheap and environmentally friendly bifunctional electrocatalytic materials is a main goal in the field of electrocatalysis,” said Yifu Zhang, lead author of the study and a researcher at the School of Chemistry of Dalian University of Technology.
Transition metal silicide alloys are unique compounds commonly used in energy-related fields, are produced inexpensively, and show promise as potential electrocatalysts for water hydrolysis. These alloys are made from transition metals, which are excellent catalysts that freely donate and accept electrons in chemical reactions, and Si atoms, which improve stability, heat resistance and accessibility transition metal atoms from the alloy when electricity is applied.
Fe and Ni, two transition metals, are ideal for use in transition metal silicide for water splitting. “Nickel silicide has been… studied extensively for its low resistance and high metallic activity, particularly… in electrochemical fields. Additionally, many recent studies have shown that Fe-Ni-based materials have potential considerable importance in the field of electrochemical water splitting. The objective One of the objectives of this work was to develop an inexpensive and environmentally friendly route to prepare iron nickel silicide as a catalyst bifunctional electrolytic water (EWS),” Zhang said.
The research team fabricated FeNiSi in two steps. First, natural clayey magadiite, a source of silicon, iron chloride and nickel chloride, was heated under pressure to create a ferric-nickel silicate. The ferric-nickel silicate was then combined and heated with magnesium and sodium chloride (table salt) to develop the ordered structure of the FeNiSi alloy. Importantly, this was the first time a metal silicide alloy had been made using this type of chemical reaction using metal silicates as the reaction material.
Electron microscopy and X-ray characterization techniques revealed that the manufacturing process created numerous pore structures in the final FeNiSi alloy, thereby increasing its specific surface area and overall electrocatalytic performance. The FeNiSi alloy reduces the potential required to separate oxygen and hydrogen from water by 308 mV for the oxygen evolution reaction (OER) and 386 mV for HER, respectively, at a current of 10 mA·cm.−2. The electrocatalyst also demonstrated sufficient durability after 15 hours of use.
The research team looks forward to FeNiSi and other transition metal silicates contributing to the synthesis of clean hydrogen gas for future energy needs.
“This work not only provides a simple method for the synthesis of intermetallic silicide with considerable porous structures, but also allows considering intermetallic silicide as a bifunctional electrocatalyst for EWS. Inexpensive and efficient intermetallic silicide-based electrocatalysts will offer new opportunities for…renewable energy. energy conversion,” Zhang said.
Other contributors include Xuyang Jing, Yang Mu, Zhanming Gao, and Xueying Dong from the School of Chemistry, Dalian University of Technology, Dalian, China; Changgong Meng from the School of Chemistry and the College of Environmental and Chemical Engineering of Dalian University of Technology; and Chi Huang of the College of Chemistry and Molecular Sciences of Wuhan University in Wuhan, China.
More information:
Xuyang Jing et al, Intermetallic ferric nickel silicide alloy derived from magadiite by magnesiothermal reaction as a bifunctional electrocatalyst for global water splitting, Nano research energy (2023). DOI: 10.26599/NRE.2023.9120104
Provided by Tsinghua University Press
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