Enhancing the electrochemical catalytic performance of novel bifunctional oxygen vacancy-enriched silver niobate (AgNbO3) through electrochemical activation

Abstract

Introducing oxygen vacancies has emerged as a powerful strategy to enhance the electrocatalytic activity of materials for the oxygen evolution reaction (OER). This approach enhances active site exposure, improves conductivity, and facilitates mass transport, thereby significantly boosting performance. This study explores the synthesis of silver niobate (AgNbO₃, ANO) enriched with oxygen vacancies; a modification known to enhance its catalytic properties. Here, ANO was synthesized with abundant oxygen vacancies using a solid-state method followed by aerosol deposition (AD) onto Ni foam substrates. The AD process rapidly produces polymeric binder-free dense ceramic films with strong interfacial adhesion, crucial for efficient electron transfer and enhanced electrocatalyst performance. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy studies confirmed the presence of oxygen vacancies, pivotal for augmenting ANO's bifunctional activity. This included achieving low overpotentials of 276 mV for the OER and 179 mV for the hydrogen evolution reaction (HER). Impressively, the ANO‖ANO water electrolyser (full cell) demonstrated a low working voltage of 1.69 V at 10 mA cm⁻², showcasing its efficacy for water splitting. The long-term durability of ANO‖ANO full cell testing confirmed a minimal voltage increase (0.01 V) after 10 hours, highlighting ANO's robust catalytic stability. Overall, this study highlights the efficacy of oxygen vacancy-rich ANO for enhancing electrocatalytic performance in water splitting, positioning it as a promising candidate for sustainable energy conversion technologies.