Carbon nanosheet/MnO2/BiOCl ternary composite for degradation of organic pollutants

Photocatalysis is a sustainable energy conversion technology for degradation of organic pollutants, while developing high-performance photocatalysts is a major task of photocatalysis. Herein, potassium citrate-derived carbon nanosheets (Cs) are prepared and acted as sacrificial templates for preparing Cs/MnO2 nanosheets arrays, and then thin BiOCl nanosheets are deposited to fabricate Cs/MnO2/BiOCl (Cs/Mn/Bi) composite photocatalyst. Through adjusting the loading amount of BiOCl, the optimized Cs/Mn/Bi-1/1 composite exhibits the highest photocatalytic activity and excellent recycling degradation performance, which degrades 97% of Rhodamine B in 25 min, 98% of Methylene blue in 40 min, and 80% of Tetracycline hydrochloride in 30 min, and the degradation rate constant is 0.129, 0.081 and 0.038 min−1, respectively. Based on electron spin resonance result, ·O2− and ·OH radicals are the reactive species for degradation of organic pollutants, and the photocatalytic mechanism is verified as the Z-scheme transfer mode. The superior photocatalytic performance is attributed to the formation of Z-scheme heterojunction between MnO2 and BiOCl, which narrows the band gap and broadens the light absorption range. Furthermore, conductive carbon layer in composite reduces the charge transfer resistance and accelerates the separation and transfer efficiency of photogenerated carriers.