Varapragasam Shelton J P, Andriolo Jessica M, Skinner Jack L, Grumstrup Erik M
Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States.
Department of Mechanical Engineering, Montana Technological University, Butte, Montana 59701, United States.
ACS Omega. 2021 Dec 10;6(50):34850-34856. doi: 10.1021/acsomega.1c05523. eCollection 2021 Dec 21.
The concentration of nitrate in natural surface waters by agricultural runoff remains a challenging problem in environmental chemistry. One promising denitrification strategy is to utilize photocatalysts, whose light-driven excited states are capable of reducing nitrate to nitrogen gas. We have synthesized and characterized pristine and silver-loaded graphitic carbon nitrides and assessed their activity for photocatalytic nitrate reduction at neutral pH. While nitrate reduction does occur on the pristine material, the silver cocatalyst greatly enhances product yields. Kinetic studies performed in batch photoreactors under both UV and visible excitation suggest that nitrate reduction to produce aqueous nitrite, ammonium, and nitrogen gas proceeds via a cooperative water reduction on the silver metal domains to produce adsorbed H atoms. By varying the percentage of silver loading onto the g-CN, the density of metal domains can be adjusted, which in turn tunes the reduction selectivity toward various products.
农业径流导致天然地表水中硝酸盐浓度升高，这在环境化学领域仍是一个具有挑战性的问题。一种很有前景的反硝化策略是利用光催化剂，其光驱动激发态能够将硝酸盐还原为氮气。我们合成并表征了原始的和负载银的石墨相氮化碳，并评估了它们在中性pH值下光催化还原硝酸盐的活性。虽然原始材料上确实发生了硝酸盐还原，但银助催化剂大大提高了产物产率。在紫外光和可见光激发下，在间歇式光反应器中进行的动力学研究表明，硝酸盐还原生成亚硝酸盐水溶液、铵和氮气是通过银金属域上的协同水还原产生吸附的H原子来实现的。通过改变负载在g-CN上的银的百分比，可以调整金属域的密度，进而调节对各种产物的还原选择性。
