One stone, two birds: A Cu-S cluster as a laccase-mimicking nanozyme and sulfite activator for phenol remediation in marine environments

Phenols are infamous pollutants in marine environments and present a grave danger to human health, which makes their efficient detection and removal serious issues. Colorimetry is a simple method for detecting phenols in water because phenols can be oxidized by natural laccase and generate a brown product. However, high cost and poor stability impede the wide-spread implementation of natural laccase in phenol detection. To reverse this adverse situation, a nanoscale Cu-S cluster, Cu4(MPPM)4 (Cu4S4, MPPM = 2-mercapto-5-n-propylpyrimidine), is synthesized. As a stable and inexpensive nanozyme, Cu4S4 shows excellent laccase-mimicking activity and prompts the oxidation of phenols. This characteristic makes Cu4S4 a perfect option for phenol detection with colorimetry. In addition, Cu4S4 also exhibits sulfite activation properties. It can degrade phenols and other pollutants with advanced oxidation processes (AOPs). Theoretical calculations show good laccase-mimicking and sulfite activation properties originating from appropriate interactions between Cu4S4 and substrates. We anticipate that the phenol detection and degradation characteristics of Cu4S4 make it a promising material to be used for practical phenol remediation in water environments.