Versatility of Ruthenium Benzothiazole Phthalocyanine Composite for Sustainable Water Electrolysis in Alkaline Media

Water splitting reaction is the most favorable path for the production of green hydrogen fuel to attain carbon neutrality for sustainable development. To develop an efficient water electrolyzer, a high-performance electrocatalyst is required to minimize the overpotential during proton reduction as well as water oxidation by maintaining the swift reaction kinetics. However, the high cost of precious electrocatalysts and instability in non-acidic media pose significant challenges, and hence nonprecious-metal catalysts have garnered attention as alternatives. However, these substitutes often suffer from unifunctionality, corrosion, and tend to lag in efficiency and stability compared with standard catalysts. Ruthenium, a lesser-cost element compared with Pt and Ir with similar hydrogen bond strength like platinum (∼65 kcal mol–1), has been overlooked as a viable catalyst for water electrolysis. Fabrication of novel ruthenium benzothiazole phthalocyanine (RuBPc) embedded with ketjen black nanoparticles (KB) demonstrated lower overpotentials of 125 and 340 mV vs RHE for HER and OER, respectively, on a carbon electrode in 1.0 M KOH electrolyte. The fabricated water electrolyzer required a lower cell voltage of 1.59 V for the HER and OER with a retainment of 77.35% energy efficiency. Benzothiazole moiety modulates the electronic structure and optimizes the Gibbs free energy value of Ru for the adsorption of intermediates during the HER/OER. Additionally, KB provides a high surface area and its conducting nature enhances the charge transfer, thereby increasing the overall kinetics of the reaction. The effective π–π interaction and the synergism between RuBPc and KB in the hybrid catalyst make it a superior catalyst for water electrolysis in alkaline media.