Plasma-assisted photo-electrocatalysis in combination with Bi5O7I for efficient ammonia synthesis

Abstract

Ammonia has a wide range of applications in industry, agriculture, and energy storage. However, the Haber–Bosch synthesis of ammonia used in industry requires a high-temperature and high-pressure catalytic environment. In this study, the catalyst Bi₅O₇I/g-C₃N₄ was prepared through a simple calcination method, leveraging the unique layered structure and suitable band gap of Bi₅O₇I. Plasma technology was employed to activate nitrogen, converting inert N₂ into more reactive NO_x⁻ intermediates, significantly reducing the reaction energy requirements. The presence of oxygen vacancies in the catalyst was found to lower the valence band energy, narrow the band gap, and extend the light absorption range, while also serving as active sites for the catalytic process. Moreover, the heterojunction structure of Bi₅O₇I/g-C₃N₄ enhanced the separation of photogenerated electron–hole pairs, improving carrier transport and enabling the participation of high-reduction potential electrons in ammonia synthesis. As a result, the catalyst achieved an ammonia yield of 59.09 mmol h⁻¹ g_cat.⁻¹ and a Faraday efficiency of 20.09% in 0.1 M KOH under ambient conditions. This work highlights the use of abundant air and water as feedstocks and demonstrates an efficient, low-cost approach to ammonia synthesis.