Sustainable valorization of waste into MXene-based nanomaterials: A quantitative analysis of circular synthesis and advanced energy applications

The integration of 2D transition metal carbides and nitrides, or MXenes, into a circular economy framework has emerged as a transformative strategy for addressing high production costs and environmental pollution. This review provides a comprehensive analysis of the waste-to-treasure paradigm, synthesizing research from 2020 to 2026 regarding the dual role of waste as both a synthesis precursor and a functional scaffold. By utilizing industrial soot, recycled aluminum, and biomass-derived carbon, researchers have developed sustainable synthesis pathways that reduce the economic barrier for specific MXene varieties to a range of approximately 20–30 $/g. Quantitatively, waste-integrated MXene composites exhibit exceptional performance across multiple domains. In energy storage systems, the use of waste-derived activated carbon as an interlayer spacer has enabled the development of electrodes with specific capacities ranging from 400 mAh/g to nearly 1000 mAh/g. Environmental applications are equally robust, with functionalized MXenes demonstrating adsorption capacities for radionuclides and heavy metals, such as uranium and cesium, in the range of 300–600 mg/g. Furthermore, these materials achieve nearly 100% efficiency in recovering precious metals from electronic waste and degrading organic pollutants through advanced oxidation processes. The discussion highlights the critical role of surface termination control and bio-inspired functionalization in enhancing structural stability under harsh chemical conditions. While laboratory-scale successes are significant, future research must address challenges regarding the standardization of waste precursors and the transition to continuous-flow industrial systems. This synthesis confirms that the repurposing of waste streams into MXene-based architectures offers a high-performance, sustainable pathway for next-generation wastewater remediation and energy conversion technologies.