Simultaneous Activation of N2 and H2O by Bi and O Double Vacancies in Bi2WO6 for Photocatalytic Ammonia Synthesis

Photocatalytic nitrogen reduction to ammonia intrinsically relies on the synergistic activation of both N 2 and H 2 O molecules by the catalyst. However, achieving simultaneous and efficient activation of these two species on a single catalyst surface remains a formidable challenge, constrained by poor N 2 adsorption and the high dissociation energy barrier of the N≡N triple bond. To address this, a vacancy engineering strategy was adopted to design and fabricate a Bi 2 WO 6 photocatalyst featuring both bismuth and oxygen dual vacancies (V Bi+O -BWO). The oxygen vacancies trap photogenerated electrons for N 2 activation, while bismuth vacancies enhance H 2 O adsorption and facilitate proton generation. Through this synergistic effect, the photocatalytic nitrogen reduction performance was significantly enhanced. Experimental results show that V Bi+O -BWO achieves an ammonia production rate of 113.14 μmol·g –1 ·h –1 , a 4.9-fold enhancement over the unmodified catalyst. N 2 -TPD results demonstrate that the dual vacancies effectively enhance N 2 chemisorption, facilitating subsequent activation. In situ FTIR confirms that N 2 adsorbs and converts on Bi 2 WO 6 via a distal pathway. This study provides new insights into the development of high-efficiency dual-vacancy photocatalytic materials.