Interface engineered Sb2O3/W18O49 heterostructure for enhanced visible-light-driven photocatalytic N2 reduction

Abstract

The direct photochemical N2 reduction reaction boasts the potential for clean and sustainable NH3 manufacturing, yet achieving this remains a significant challenge. To activate and cleave the nonpolar N≡N bond and accelerate the transport and separation of charge carriers during photocatalysis, the design and facile synthesis of active, robust, cheap, and earth-abundant photocatalysts is crucial. Here, we demonstrate efficient and stable visible light fixation of N2 to NH3 by constructing a novel heterostructure consisting of two-dimensional Sb2O3 nanosheets and one-dimensional W18O49 nanowires. A remarkable NH3 production rate of up to 731 μgNH3 h−1 gcat.−1 is attained in visible light over the nanocomposite without cocatalyst, 5.5-fold and 3.4-fold improvement over that of discrete Sb2O3 and W18O49 respectively, which also significantly exceeds many previous reported photocatalytic systems. The superior photocatalytic performance can be attributed to the unique structure of the composites, which provides ample exposed surface catalytic sites with a high density of oxygen vacancies, promoting the adsorption and activation of N2 molecules to form *NNH. Equally importantly, the interface between Sb2O3 and W18O49 greatly facilitates charge carrier migration and separation. Further density functional theory calculations manifest that the interfacial metal sites on Sb2O3/W18O49 serve as the main active centers which possess a strong donating electron ability to the empty N2 antibonding orbitals to trigger the following NH3 synthesis. This work provides a simple and effective method to modify metal oxides for enhancing N2 photofixation.