Tailored Ni/Pd Phthalocyanine Electrocatalyst for Efficient and Stable Water Splitting in Alkaline Media

Abstract

Energy is fundamental to life, and its generation must align with ecological sustainability. Among various energy sources, hydrogen stands out as a sustainable carrier. A hydrogen-based economy depends on efficient hydrogen production, achievable via water electrolysis using robust electrocatalysts. While platinum (Pt) exhibits excellent catalytic activity and low overpotential, nickel (Ni) and palladium (Pd) have emerged as promising alternatives due to their favorable position on the hydrogen evolution reaction (HER)/oxygen evolution reaction (OER) volcano plot. This study reports the synthesis and characterization of a bimetallic composite, nickel/palladium(II) tetra naphthalene phthalocyanine (Ni/PdTNBPc), using physicochemical and electrochemical techniques. The catalytic performance of Ni/PdTNBPc was evaluated for the HER and OER. The composite showed nearest activity than benchmark catalysts Pt/C and IrO2. Linear sweep voltammetry (LSV) revealed a positive shift in onset potentials for HER and OER, indicating enhanced feasibility in 1 M KOH. Performance improvement is attributed to embedded Pd, which increases conductivity and active sites for H* adsorption Ni/PdTNBPc exhibited a current density of 10 mA cm-2 at overpotentials of −62 mV for HER and 282 mV for OER, with corresponding Tafel slopes of 42 mV/dec (HER) and 38 mV/dec (OER) for HER and OER respectively, outperforming PdNC and NiTAPc and matching Pt/C and IrO2. The composite also demonstrated excellent stability over 66 h. Containing less than 8 wt% Ni-Pd, this hybrid catalyst offers an efficient and economical solution for water splitting.