Journal of Colloid and Interface Science, Vol.566, 495-504, 2020
Construction of phosphorus-doped carbon nitride/phosphorus and sulfur co-doped carbon nitride isotype heterojunction and their enhanced photoactivity
Photocatalysis was one of the most promising techniques for environmental remediation. Exploring photocatalysts with high efficiency, low cost and easy preparation was still an ongoing issue. In this work, phosphorus-doped carbon nitride/phosphorus and sulfur co-doped carbon nitride (P-C3N4/PS-C3N4) isotype heterojunction was prepared by a two-step calcination method. The composite displayed a sheet-like structure with a surface area of 23 m(2)/g. Compared with pure C3N4, band gaps of P-C3N4 and PS-C3N4 were only slightly modified during the heteroatom-doping process. Therefore, a well-matched band alignment was constructed, which not only improved the separation efficiency of photogenerated electron-hole pairs, but also well preserved the high oxidizability of holes on valance band and good reducibility of electrons on conduction band. Because of the similarity in physicochemical properties, the interface resistance between P-C3N4 and PS-C3N4 was low, which accelerated the electron transfer and prolonged the lifetime of charge carriers. Although the visible-light utilization was somewhat low in comparison with P-C3N4 and PS-C3N4, by taking advantage of above merits, P-C3N4/PS-C3N4 displayed the high photocatalytic activity in rhodamine B degradation, and the reaction rate constant was 0.183 min(-1), about 8.7 and 4.0 times higher than those of P-C(3)N(4 )and PS-C3N4. Besides high catalytic activity, isotype heterojunction displayed good recyclability, since 95.3% of catalytic activity was maintained after the 5th cycle. The method presented here was facile, economic and environmentally benign, thus it was highly attractive for the application in environmental remediation. (C) 2020 Elsevier Inc. All rights reserved.
Keywords:C3N4 nanosheet;Isotype heterojunction;Heteroatom-doping;Visible-light;Charge transfer;Photodegradation