Molten salt synthesis of low-dimensional nanostructured perovskite oxide electrocatalysts for oxygen evolution reaction: a review

Abstract

The global energy crisis and severe environmental problems have driven extensive research into renewable energy alternatives over the past decade. Hydrogen energy, produced via water splitting, stands out as a good candidate owing to its high energy density and superior environmental compatibility. While various hydrogen production methods exist, water electrolysis remains the most efficient and reliable approach when coupled with renewable energy sources. However, its large-scale applications are restricted owing to the insufficient development of high-performance electrocatalysts for oxygen evolution reaction (OER). In recent years low-dimensional nanostructured perovskite oxides, including single perovskites (ABO3), double perovskites (A2BB′O6), and quadruple perovskites (AA′3B4O12), have been regarded as attractive OER electrocatalysts because of their compositional and structural flexibilities, large surface area, high activity, and good stability. Among the developed alternative synthesis methods, molten salt synthesis (MSS) has gained prominence for its unique advantages in tailoring nanostructured perovskite oxides. In view of the rapid development in this field, this review comprehensively evaluates MSS-derived low-dimensional perovskite oxide OER electrocatalysts, which covers (i) historical development and principles of MSS process, (ii) comparative advantages over other synthesis methods, (iii) fundamental OER mechanisms and performance metrics, (iv) critical analysis of MSS-synthesized ABO3 perovskites, A2B′B″O6 double perovskites, and AA′3B4O12 quadruple perovskites used for OER electrocatalysts. Despite progress, challenges remain in scaling MSS method for complex nanostructures and enhancing their mass-specific activities. Finally, this review also provides insights into the potential challenges on low-dimensional perovskite oxide nanostructures for OER electrocatalysis with high efficiency and outlines the future prospects in nanostructural engineering.