Enhancing activity and stability of RuO2 as a bifunctional catalyst using a thermally tuned α-MnO2 interlayer for hydrogen production†

Abstract

Hydrogen is a vital and significant alternative fuel that can play a major role in reducing the impact of climate change. Developing robust and highly active bifunctional catalysts is essential for achieving sustainable electrolytic hydrogen generation. The electrocatalysts used for the OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) are prone to corrosion, particularly under alkaline conditions. Developing engineering solutions to provide stability while maintaining activity of RuO₂ as a bifunctional catalyst remains a significant and major problem. In this study, we present a hierarchical heterostructure synergy effect that was generated through a straightforward electrode fabrication method, as opposed to a highly intensive and extremely challenging chemical synthesis route where heat-treated α-MnO₂ (referred to as 400-α-MnO₂) is used as an interlayer for RuO₂. With the help of detailed EIS and XPS analysis, we observed that the presence of 400-α-MnO₂ creates an unobstructed channel for electron transfer to RuO₂, resulting in improved activity towards both the OER and HER, as well as increased durability. The heterojunction catalyst has also been evaluated in an AEM-based full cell, which exhibits remarkable stability and activity with a minimal RuO₂ mass loading of 189 μg cm⁻². The proposed engineered interface, using 400-α-MnO₂, surpasses the stability and activity limitations of RuO₂ in an alkaline environment.