NiFeMo layered triple hydroxide and MXene heterostructure for boosted oxygen evolution reaction in anion exchange membrane water electrolysis

Abstract

Efficient, low cost and stable electrocatalysts are highly desirable for sluggish oxygen evolution reaction (OER) in alkaline water electrolysis for hydrogen production. Interfacial engineering of heterostructures is quite beneficial for improving charge transfer efficiency at the interface. In this context, heterostructures of layered triple hydroxides (LTHs) and MXenes have shown great potential for OER electrocatalysts owing to their 2D-2D structure and unique physiochemical properties. Coupling LTHs with MXenes can potentially enhance their conductivity and stability, thereby boosting OER activity. In this study, we report a heterointerface between NiFeMo-LTH on Ti3C2Tx MXene, which exhibits superior catalytic activity and stability in alkaline freshwater as well as seawater reducing the activation energy. Importantly, the heterostructure achieved a current density of 100 mA cm-2 at by the cost of 292 mV and 340 mV overpotentials in alkaline saline water and real seawater, respectively and showed robustness over 100 h without any hypochlorite formation causing corrosion in alkaline real seawater. Moreover, NiFeMo-LTH/MXene was also explored in alkaline anion exchange membrane water electrolyzer (AEMWE) achieving a current density of 750 mA cm-2 at 2.16 V cell voltage at operating temperature of 60 ⁰C with energy efficiency of 60.5%. The Raman analysis and XPS analysis post stability test demonstrates the easy electron transfer from LTH to MXene at heterointerface leading to formation of NiOOH electroactive species facilitates the OER activity.