A colorimetric paper sensor based on a cation-exchange strategy has been developed for the visual determination of heavy metal ions. Belt-like ZnSe nanoframes as colorimetric reagents were prepared from ZnSe·0.5N₂H₄ hybrid nanobelts as precursors via a hydrothermal method. With the decomposition and release of N₂H₄ ligands, the regular belt-like nanostructures of the precursors evolved into belt-like nanoframes, which consisted of numerous ZnSe nanocrystals. Inspired by the cation-exchange characteristic of chalcogenides, the as-prepared belt-like ZnSe nanoframes were employed to fabricate a colorimetric paper sensor for the detection of heavy metal ions. Owing to the color change arising from a composition change, the colorimetric paper was successfully applied to detect Ag⁺, Cu²⁺, and Hg²⁺ at room temperature. Depending on the color change and its intensity, heavy metal ions of Ag⁺, Cu²⁺, and Hg²⁺ can be individually identified and their concentrations can be determined. Particularly for Cu²⁺, its visually detected concentration can be down to 1 ppm. More importantly, the fabricated colorimetric paper sensor displays excellent anti-interference properties from various typical cations and anions. Considering its low cost and practicality, expectedly it can be used for practical application.

已开发出一种基于阳离子交换策略的比色纸传感器，用于视觉测定重金属离子。通过水热法，以ZnSe·0.5N ₂ H ₄杂化纳米带为前驱体，制备了带状ZnSe纳米框架作为比色试剂。随着N ₂ H ₄的分解和释放配体，前体的规则带状纳米结构演变成带状纳米框架，由许多ZnSe纳米晶体组成。受硫族化物阳离子交换特性的启发，将制备的带状ZnSe纳米框架用于制备比色纸传感器，用于检测重金属离子。由于组成变化引起的颜色变化，该比色纸已成功应用于室温下的Ag ⁺，Cu ²⁺和Hg ²⁺的检测。根据颜色变化及其强度，可以分别识别Ag ⁺，Cu ²⁺和Hg ^2+的重金属离子并确定其浓度。特别是对于铜^2+时，其视觉检测浓度可降至1 ppm。更重要的是，制造的比色纸传感器对各种典型的阳离子和阴离子显示出出色的抗干扰性能。考虑到它的低成本和实用性，预期它可以用于实际应用。