Xu Zhengdong, Chen Yang, Wang Binghao, Ran Yu, Zhong Junbo, Li Minjiao
College of Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000, PR China.
Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, School of Chemistry and Environmental Engineering, Sichuan University of Science and Engineering, Zigong 643000, PR China.
J Colloid Interface Sci. 2023 Dec;651:645-658. doi: 10.1016/j.jcis.2023.08.012. Epub 2023 Aug 5.
The introduction of nitrogen vacancies into polymeric carbon nitride (PCN) has been attested to be a reliable strategy to enhance photocatalytic performance. Nitrogen vacancies were considered as active sites to promote the adsorption of target molecules and capture photoexcited electrons to inhibit the recombination of charge pairs, accelerate photoinduced electrons to participate in photocatalytic reaction. In this paper, a series of PCN with rich nitrogen vacancies were prepared by etching of chromic acid solution. Sample 20KCSCN had the highest photocatalytic performance whose evolution efficiency of CO to CO and CH can reach 3.9 and 0.5 μmol·g·h, respectively. These evolution efficiencies are 2.9 and 4 times higher than that of the PCN. Meanwhile, 20KCSCN demonstrates high CO conversion selectivity and stability. The successful introduction of nitrogen vacancies not only increases the active sites of PCN surface, but also optimizes the optical structure, which dramatically boosts the separation of photoexcited charge pairs and the reduction capacity of photogenerated electrons. The enhancement mechanism for photocatalytic CO reduction performance of PCN was proposed. Besides, photocatalytic H evolution experiments were performed on all samples to confirm the universality of PCN photocatalytic activity enhancement etched by chromic acid solution. H evolution rate on 20KCSCN can reach 652 μmol·g·h, which is 1.6-fold higher than that on PCN (254 μmol·g·h) after 4 h irradiation under a 300 W Xe lamp. This work offers new venue for introducing nitrogen vacancies in PCN to regulate photoexcited charge pairs transfer. The photocatalytic enhancement of CO reduction could be used to alleviate the serious issue of excessive CO emission and energy crisis.
将氮空位引入聚合氮化碳（PCN）已被证明是提高光催化性能的可靠策略。氮空位被视为促进目标分子吸附并捕获光激发电子以抑制电荷对复合、加速光生电子参与光催化反应的活性位点。本文通过铬酸溶液蚀刻制备了一系列具有丰富氮空位的PCN。样品20KCSCN具有最高的光催化性能，其将CO转化为CO和CH的演化效率分别可达3.9和0.5 μmol·g·h。这些演化效率分别比PCN高2.9倍和4倍。同时，20KCSCN表现出高的CO转化选择性和稳定性。氮空位的成功引入不仅增加了PCN表面的活性位点，还优化了光学结构，极大地促进了光激发电荷对的分离以及光生电子的还原能力。提出了PCN光催化CO还原性能的增强机制。此外，对所有样品进行了光催化析氢实验，以证实铬酸溶液蚀刻增强PCN光催化活性的普遍性。在300 W Xe灯下照射4 h后，20KCSCN上的析氢速率可达652 μmol·g·h，比PCN（254 μmol·g·h）高1.6倍。这项工作为在PCN中引入氮空位以调节光激发电荷对转移提供了新途径。光催化CO还原的增强可用于缓解CO排放过量和能源危机这一严峻问题。
