High-Performance Formaldehyde Sensing Using Paper-Based Fluorescent Copper Nanoclusters

Highly sensitive detection of formaldehyde (FA) is of great importance to protect human health against its adverse effect. Herein, we constructed copper nanoclusters (Cu NCs) with strong luminescence capable of rapid, sensitive, and visual detection of FA, which was self-assembled using D-penicillamine (DPA) as the protecting ligand. Common physical measurements were carried out to analyze the as-fabricated samples (DPA-Cu NCs). Experimental results revealed its strong red fluorescence (FL), large Stokes shift, and a long fluorescence lifetime. Furthermore, DPA-Cu NCs presented self-assembled aggregation-induced emission (SAIE) property and achieved a fluorescence quantum yield (FLQY) as high as 76.26% in the solid state. Notably, FA could quench the fluorescence of Cu NCs effectively. The possible quenching mechanism was attributed to static quenching. Moreover, a paper-based visual sensor was built by immobilizing the DPA-Cu NCs probe on the filter paper, which can achieve on-site detection of FA.