P-058

Aldona Balčiūnaitė

aldona.balciunaite@ftmc.lt

Sukomol Barua, Jūratė Vaičiūnienė, Loreta Tamašauskaitė-Tamašiūnaitė, Eugenijus Norkus

Department of Catalysis, Center for Physical Sciences and Technology (FTMC), Lithuania

Activity of Non-Noble Transition Metal-Based 3D Electrocatalysts for Alkaline Natural and Simulated Seawater Splitting

Only 2.5 % of the world’s water is freshwater, and this resource is becoming increasingly scarce. Large-scale hydrogen production through water splitting places significant pressure on these limited freshwater supplies. In comparison, seawater, which makes up approximately 97.5 % of the Earth's total water, is vastly more abundant. Therefore, replacing freshwater with seawater as an electrolyte for hydrogen production offers a sustainable and scalable solution. 

In this study, we demonstrate a simple, one-step synthesis of three-component NiMnCo electrocatalysts supported on a titanium (Ti) substrate (denoted as NiMnCo/Ti) using the electrochemical deposition method with a dynamic hydrogen bubble template technique. We also report their electrocatalytic performance for the hydrogen evolution reaction (HER) in alkaline seawater (1 M KOH + natural seawater) and simulated seawater (1 M KOH + 0.5 M NaCl). The three-component NiMnCo/Ti electrocatalyst exhibited a unique cauliflower curd-shaped micro-sized nodular architecture. The HER activity of these catalysts was investigated by using Linear Sweep Voltammetry (LSV) in the alkaline environment at various temperatures. The polarization curves of the prepared NiMnCo/Ti catalysts were recorded in working electrolytes at a potential scan rate of 10 mV·s-1 at a temperature range from 25 ℃ to 75℃. The current densities increased as the temperature rose from 25°C to 75°C. At 25°C, the fabricated NiMnCo/Ti electrocatalyst demonstrated excellent HER activity in simulated seawater and alkaline seawater, with low overpotentials of 29 mV and 59 mV, respectively, to achieve a current density of 10 mA cm⁻². These non-noble metal-based catalysts also exhibited exceptional long-term stability at a constant potential of -0.232 V (vs. RHE) and a constant current density of 10 mA cm⁻² for 50 Hrs. Additionally, a multi-step chronopotentiometry test with current densities ranging from 20 mA cm⁻² to 100 mA cm⁻² demonstrated their sustainable durability and suitability for practical alkaline water splitting applications.