Synthesis and Electrochemical Characterization of Lanthanide–Nickel Binaries as Electrocatalysts for Direct Seawater Electrolysis

• Joshua Rubenstein, Chemistry, University of Delaware

• Svilen Bobev, Department of Chemistry and Biochemistry, University of Delaware
• Emil Hernandez – Pagan, Department of Chemistry and Biochemistry, University of Delaware

Hydrogen (H₂) produced through water electrolysis is a promising clean energy source, but most electrolysis research has focused on ultra-pure water. Direct seawater electrolysis offers a more sustainable alternative because seawater is Earth’s most abundant water resource. However, dissolved ions in seawater can promote competing reactions, catalyst degradation, and reduced electrochemical performance. This research investigates lanthanide–nickel binary alloys as potential selective and stable electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) during direct seawater electrolysis.

Lanthanide–nickel binary alloys containing cerium, lanthanum, and praseodymium were synthesized using arc melting with varying compositions to produce intermetallic materials. The synthesized alloys were characterized using powder X-ray diffraction (PXRD) to identify the crystalline phases present. Electrochemical performance was evaluated in seawater using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). To date, Ce₁Ni₉₉, Ce₁₀Ni₉₀, and Ce₂₀Ni₈₀ have been synthesized and tested, while La₂₀Ni₈₀ and Pr₂₀Ni₈₀ have been synthesized for future electrochemical evaluation.

Preliminary results demonstrate that lanthanide concentration significantly influences electrocatalytic performance. Among the cerium-based alloys studied, Ce₁₀Ni₉₀ exhibited superior HER and OER activity compared with both Ce₁Ni₉₉ and Ce₂₀Ni₈₀. These findings suggest that an optimal lanthanide-to-nickel ratio exists since both lower and higher lanthanide concentrations reduce performance. Ongoing work is focused on comparing the electrochemical performance of Ln₂₀Ni₈₀ (Ln = La, Ce, Pr) to determine how the identity of the lanthanide influences catalyst activity. By establishing composition–structure–property relationships in lanthanide–nickel alloys, this work aims to accelerate the development of efficient, earth-abundant electrocatalysts for sustainable hydrogen production through direct seawater electrolysis.