Mn-doped carbon dots as a visible-light-driven catalyst for degradation of acid fuchsin and malachite green

Visible light absorbing manganese (Mn) -doping CDs were prepared by hydrothermal method, which exhibit orange-red emitting, and used as a photocatalyst for degrading acid fuchsin and malachite green. Through XPS analysis, Mn was successfully doped into the CDs. Under irradiation of the visible light, both of the degradation rates reached more than 95% in a short time. The used concentration of Mn-doping CDs is much lower than conventional ones, revealing the quite strong degradation ability. By comparing the optimal PL and UV-Vis absorption spectra of the CDs with and without Mn-doping, the effect of Mn-doping was revealed on the catalytic performance that Mn-doping altered the light-absorption position to the visible light region with a marked red-shift and the recombination rate of electron-hole pairs was reduced in the photo-chemical reaction process. Metal-doped CDs have not been used as photocatalysts, which have been achieved in this paper. Meanwhile, trap experiments were carried out to detect the reactive species related to the photo-degradation process of the two dyes, displaying that O-center dot(2)- and OH center dot play the critical roles.