Abstract:
A series of Ag
2S-Ag
2CO
3 (4 % , 8 % , 16 % , 32 % and 40 % Ag
2S), Ag
2CO
3@Ag
2S (32 % Ag
2S) and Ag
2S@Ag
2CO
3 (32 % Ag
2S) heterojunction photocatalysts were fabricated by coprecipitation or successive precipitation reaction. The obtained catalysts were analyzed by N
2physical adsorption, powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR), Raman spectroscopy(Raman) and UV-VIS diffuse reflectance spectroscopy(UV-VIS DRS). Under visible light irradiation, the influences of Ag
2S content and core-shell property on photocatalytic activity and stability were evaluated in studies focused on the degradation of methyl orange (MO) dye and phenol. Results showed that excellent photocatalytic performance was obtained over Ag
2S/Ag
2CO
3 heterojunction photocatalysts with respect to Ag
2S and Ag
2CO
3. With optimal content of Ag
2S (mass fraction of 32 % ), the Ag
2S-Ag
2CO
3 showed the highest photocatalytic degradation efficiency. Moreover, the structured property of Ag
2S/Ag
2CO
3 greatly influenced the activity. Compared with Ag
2S-Ag
2CO
3 and Ag
2CO
3@Ag
2S, core-shell like Ag
2S@Ag
2CO
3 demonstrated the highest activity and stability. The main reason for the boosting of photocatalytic performance was due to the formation of Ag
2S/Ag
2CO
3 heterojunction with well contacted interface and unique electron structures. Ag
2S/Ag
2CO
3 heterojunction could significantly increase the separation efficiency of the photo-generated electrons (e
-) and holes(h
+), and production of oOH radicals. More importantly, the low solubility of Ag
2S shell could effectively protect the core of Ag
2CO
3, which further guarantees the stability of Ag
2CO
3.