Enhancing photocatalytic N2 fixation under ambient conditions through Zn vacancy-mediated engineering of Cd0.5Zn0.5S

Abstract

In this work, Zn vacancy-mediated Cd_0.5Zn_0.5S was synthesized by a facile hydrothermal approach and the resultant samples were thoroughly characterized using various technologies. The photocatalytic performance of the as-synthesized samples was evaluated by photocatalytic N₂ fixation under ambient conditions. The findings reveal a significant enhancement in ammonia evolution from N₂ fixation with an increase in Zn vacancies. Notably, the maximum ammonia evolution yield reached 2.93 mmol L⁻¹ with V_Zn–Cd_0.5Zn_0.5S synthesized at 200 °C under visible light irradiation for 2 h, marking an efficiency approximately 7.9 times higher than that of the sample synthesized at 180 °C. Additionally, density functional theory (DFT) calculations indicate that introducing zinc vacancies into Cd_0.5Zn_0.5S narrows its bandgap, facilitating the migration of photogenerated electrons from the valence band to the conduction band, thereby boosting its photocatalytic nitrogen reduction performance. This research offers novel strategies for enhancing solar energy conversion efficiency and deepens our understanding of the photoreduction mechanism of N₂.