Assessing MXene-supported polyoxometalate electrocatalysts: Is MXene always a miracle material for HER and OER applications?

Abstract

The growing demand for renewable energy is driving researchers to focus on sustainable energy solutions. Water splitting reactions hold significant potential for energy generation, with the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) being key processes. These reactions are typically enhanced by advanced materials like Pt and Ir/Ru oxides. Numerous electrocatalysts have been investigated in this area. This study aimed to leverage the high conductivity, stability, and large surface area of Ti3C2Tx MXene in combination with electroactive polyoxometalates (POMs) to improve water-splitting performance. However, the results were disappointing. The composites displayed low catalytic activity for both HER and OER. Oxidation issues were mitigated using cold sonication and alkaline conditions, but the incorporation of POMs increased overall resistance rather than enhancing charge transfer, leading to reduced efficiency of the electrocatalyst. Interestingly, the POM-MXene composites underperformed compared to POMs alone in water-splitting applications. As a result, these composites are better suited for alternative electrochemical applications rather than for water splitting.