Built-in electric field intensified by SPR effect to drive charge separation over Ag-AgI/Sb2S3 heterojunction for high-efficiency photocatalytic metronidazole mineralization

Abstract

The photocatalytic activity of semiconductor is extremely limited due to the rapid recombination of photo-generated carriers and low utilization of solar energy. Herein, a novel Ag-AgI/Sb2S3 (A-S) heterojunction with superior photocatalytic activity was synthesized, in which the optimal Ag-AgI/Sb2S3 heterojunction exhibited 31 times photocatalytic activity of metronidazole removal than that of than that of Sb2S3. The excellent performance of the prepared photocatalysts could be attributed to the synergy of surface plasmon resonance effect by in situ-generated Ag nanoparticles and the built-in electric field of heterostructure, which would broaden the response range of solar light and accelerate the transfer of photogenerated carriers. Besides, characterization and theoretical calculations confirm Ag atoms acquire abundant electrons from Sb atoms of Sb2S3, allowing Ag+ to reduce to Ag0. Meanwhile, a portion of the Ag0 plasma-induced hot electrons reduce O2 to ·O2–, while the remaining portion flows to AgI and circulates in AgI and Ag0 to form a closed loop, thus eliminating the photo-corrosion of AgI. The stability of A-S photocatalyst was also confirmed by five cycle-tests. Furthermore, a reasonable photocatalytic mechanism was proposed by analyzing the intermediates of metronidazole. This work has implications for designing efficient photocatalysts using high-performance materials based on Ag nanoparticles.