Fig. 3
a Catalytic reaction of 2,4-DP and 4-AP to produce colored adduct by laccase-mimicking H–Mn–Cu NFs with the absorption spectra for comparing the laccase-like activity of H–Mn–Cu NFs with those of control samples such as MnO2 NFs, Cu3(PO4)2 precipitates, and free laccase. b Photographs and the corresponding absorption intensities for confirming the laccase-like activity of H–Mn–Cu NFs rather than other oxidase activity. [Sample specifications: (i) H–Mn–Cu NFs reacted with 2,4-DP, (ii) supernatant with ABTS and HRP, added after the centrifugation of (i), and (iii) after adding H2O2 into (ii)]