Exploring Synergy: Pd/H_<i>y</i>Mn_0.8Co_0.2O₂ Nanocomposite for Enhanced Overall Water Splitting toward Sustainable Green Hydrogen Production

Abstract

H y Mn 0.8 Co 0.2 O 2 nanosheets (H y MnCoO 2 NS) exhibit encouraging electrocatalytic Hydrogen Evolution Reaction (HER) activity but limited Oxygen Evolution Reaction (OER) performance in an alkaline medium. However, the incorporation of palladium nanoparticles (Pd NPs) onto the H y MnCoO 2 NS demonstrates improved and stable HER/OER as well as overall water splitting (OWS) by the composite (Pd/H y MnCoO 2 ). A strongly coupled metal/metal oxide synergy imparts efficient bifunctional catalytic activity in the composite. The Pd/H y MnCoO 2 composite achieves a current density ( j ) of 10 mA cm –2 in a 1.0 M KOH electrolyte with an applied overpotential of 210 mV for HER and 390 mV for OER and retains stable performance for ∼24 h. A two-electrode Pd/H y MnCoO 2 ||Pd/H y MnCoO 2 electrolyzer efficiently performs the OWS at a cell voltage of 2.0 V, operating continuously for ∼120 h without significant change in current density, highlighting a cost-effective and scalable electrolyzer fabrication. Enhanced mass activity (MA), electrochemical active surface area (ECSA), turnover frequency (TOF), and Faradaic efficiency (FA) underscore the catalyst’s potential for practical applications. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and density functional theory (DFT) studies reveal strong interfacial coupling between Pd NPs and H y MnCoO 2 NS, modulating the electronic structure and enhancing catalytic activity. This work underscores the promise of a strongly coupled metal/metal oxide system as an economical alternative to a fully noble metal-based electrocatalyst for water splitting applications. The Pd/H y MnCoO 2 ||Pd/H y MnCoO 2 electrolyzer when connected to a 3.00 V solar panel under daylight demonstrates encouraging OWS paving the way for sustainable green hydrogen production.

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