In-situ construction of ZnO/Sb2MoO6 nano-heterostructure for efficient visible-light photocatalytic conversion of N2 to NH3

Abstract

Photocatalytic nitrogen fixation provides a low-cost manner to produce ammonia. The low conversion yield from photon to ammonia significantly hindered progress in this area. Herein, we have developed an n-n heterojunction of ZnO/Sb2MoO6 by a facile procedure and explored its photocatalytic ability for the N2 fixation process. Further physicochemical analyses scrutinize the structural, chemical, optical, morphological, and textural features of ZnO and Sb2MoO6 in the pure samples and junction material. Moreover, the valence-band XPS and Mott−Schottky results suggest a conceivable band edge potential approving the n-n heterojunction with a built-in electric field between ZnO and Sb2MoO6. The optimal ammonium generation can be obtained in the presence of ZnO/Sb2MoO6 (20%) (20% refers to weight percentages of Sb2MoO6) nanocomposite (2800 μmol/g·L), which is ∼35.2 and 25.7-times higher than those of the pure ZnO and Sb2MoO6, respectively. The optical response of the prepared nanocomposites improved with increasing Sb2MoO6 content. However, increasing the weight percentage of Sb2MoO6 to 30% led to the aggregation of nanoparticles, reduced active sites and, consequently, poor photocatalytic performance. The best photocatalytic ability of ZnO/Sb2MoO6 (20%) nanocomposite can be attributed to the more absorption of visible light, morphology, and efficient separation of photogenerated charges. The effects of solution pH and solvent type on the ammonium production reaction were evaluated and discussed in detail. The stability of the prepared ZnO/Sb2MoO6 photocatalyst was also assayed in successive experiments during 4 runs. This research provides a potential strategy to attain superior conversion efficiency in N2 fixation reactions.