P-034

Huma Amber

huma.amber@ftmc.lt

Aldona Balčiūnaitė, Loreta Tamašauskaitė-Tamašiūnaitė,  Zita Sukackienė, Jūratė Vaičiūnienė, Eugenijus Norkus

Center for Physical and Technological Sciences (FTMC), Vilnius, Lithuania

Efficient Overall Water Splitting in an Alkaline Medium Using Palladium-Enhanced Cobalt-Based Coatings on Flexible Copper-Coated Polyimide Surface

The development of highly efficient and low-cost electrocatalysts for overall water splitting (OWS) is of significant importance for the production of H2. The most commonly used bifunctional catalysts typically exhibit excellent activity for one half-reaction, but this is often accompanied by reduced activity for the other half-reaction, resulting in moderate overall performance for water splitting. Herein, an innovative approach to OWS in an alkaline medium is presented, utilising palladium-enhanced cobalt-phosphorus (Co-P) and cobalt-iron-phosphorus (Co-Fe-P) coatings on flexible copper-coated polyimide (Cu/PI) surface. The facile electroless deposition method was employed to fabricate Co-P and Co-Fe-P coatings on the flexible Cu/PI substrate, followed by Pd modification via a galvanic displacement method. Although other noble metals, such as platinum (Pt) and rhodium (Rh), are frequently utilized in catalytic applications due to their superior catalytic efficiency, Pd was selected for this study due to its distinctive equilibrium of catalytic performance and comparatively reduced cost. Sodium hypophosphite (NaH2PO2) was used as the reducing agent. The structural, morphological, and elemental properties of the coatings were characterized using a range of analytical techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The electrocatalytic performance for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) was evaluated in 1 M KOH using a three-electrode setup. In contrast, the OWS performance was assessed in a two-electrode system.

Pd-modified Co-P and Co-Fe-P coatings exhibited superior bifunctional catalytic activities compared to Co-P and Co-Fe-P, with low overpotentials and high current densities for both HER and OER. The synergistic effects of Pd incorporation and the bimetallic composition significantly enhanced active site availability and charge transfer kinetics. It is crucial to note that the cell, which is assembled by using identical Pd-Co-Fe-P catalysts as both the cathode and anode, requires a cell voltage of 1.69 V to achieve a current density of 10 mA cm-2. In contrast, the Co-Fe-P catalyst requires a cell voltage of 1.81 V.  The flexible Cu/PI substrate ensures mechanical durability, which makes the system ideal for large-scale applications. The Pd-modified Co-P and Co-Fe-P coatings on flexible Cu/PI substrate demonstrate excellent catalytic activity, stability, and scalability, making them promising candidates for efficient and durable OWS in an alkaline media.

Acknowledgement:

This research was funded by a grant (No. P-MIP-23-467) from the Research Council of Lithuania.