Improved nitrogen adsorption and visible-light-driven nitrogen oxidation activity of divacancies-engineered ZnS

Abstract Currently, nitrate production from nitrogen under mild conditions is highly desirable. In this work, visible-light-responsive ZnS with divacancies is obtained by a simple hydrothermal method. Under visible light irradiation, the average nitrate producing rate is 0.71 mg g-1h−1, which is higher than the most reported photocatalysts. It also shows good nitrate selectivity. The pothole morphology evidently increases the surface area of ZnS-A, favoring the adsorption and activation of N2. Divacancies significantly widen light adsorption range, strengthen interaction of nitrogen with photocatalyst and provide more adsorption sites. Meanwhile, influences of vacancies on adsorption and activation of nitrogen are investigated. Compared to Zn vacancy, the adsorption of nitrogen can be obviously enhanced by S vacancy, while it is boosted to the largest extent by divacancies. Besides, divacancies weaken the adsorption of H2O, inhibiting the competitive water splitting reaction. Finally, an oxidation mechanism is proposed to explain the generation of nitrate. This work suggests that divacancies engineering is an efficient strategy to make full use of solar energy.