Noble Metal-Decorated MXene Nanohybrids: A Comprehensive Review of Au, Ag, Pd, and Pt Composites for Energy & Environmental Applications

MXenes, a rapidly expanding family of two-dimensional transition metal carbides and nitrides, exhibit a distinctive combination of metallic-level electrical conductivity, pronounced hydrophilicity, and rich surface chemistry arising from their abundant surface terminations (e.g., –O, –OH, –F). These attributes clearly distinguish MXenes from conventional 2D semiconductors and graphene-based systems and render them highly attractive platforms for electrocatalysis and chemical/biosensing. In this context, decorating MXenes with noble metals has emerged as a powerful strategy to impart and enhance sensing and catalytic functionalities, while simultaneously utilizing the intrinsic advantages of the MXene scaffold. This review provides a comprehensive overview of recent advances in MXene-based composites incorporating noble metals, with a particular focus on gold (Au), silver (Ag), palladium (Pd), and platinum (Pt). We systematically summarize synthesis methodologies, sample preparation and integration routes, and key performance metrics, emphasizing how interfacial engineering between MXenes and noble metals gives rise to synergistic effects in electrochemical catalysis and sensing platforms. Finally, we discuss current challenges and offer perspectives on future research directions aimed at further optimizing MXene–noble metal nanoparticle composites and expanding their applicability across next-generation energy, environmental, and biosensing technologies.