A triboelectric nanosensor based on ultra-thin MXene composite paper for heavy metal ion detection

Heavy metal pollution has become increasingly serious in recent decades with the progress of industrialization, posing a significant threat to human health. This raises the demand for portable and ease of use heavy metal ion detection devices. In this study, we develop ultra-thin (5µm) and highly flexible composite paper of MXene/bacterial cellulose (M/BCx, with x denoting the BC content) and apply it in a self-powered triboelectric nanosensor (TENS) to do heavy metal ion detection. The M/BCx composite paper is fabricated using a simple vacuum filtration method, and combines the advantages of the high electrical conductivity of MXene with the excellent mechanical properties of BC. The TENS employs the M/BCx composite paper and PTFE as the friction layers, and the influences of different ratios of M/BCx on the electrical signals is investigated. The TENS shows high sensitivity in the detection of Cu2+, Cr3+, and Zn2+, as the detection limit is as low as 1µM without the need of ligand molecules. A linear range of 10 µM to 300 µM is obtained. The TENS also shows excellent stability after more than 10,000 continuous operations. This simple-structured, cost-effective and durable TENS device provides new insights into the methodology of heavy metal ion detection and can be further developed for the detection of the corresponding ions in serum.