具有碳空位超薄g-C_(3)N_(4)纳米片可见光下产过氧化氢

Enhanced hydrogen peroxide production performance in visible light from ultra-thin g-C_(3)N_(4)nanosheets with carbon vacancies

光催化产过氧化氢(H_(2)O_(2))作为一种绿色可持续发展技术,相比于工业上常用的蒽醌法,具有清洁无污染、安全、低能耗及低成本等优点。石墨相氮化碳(g-C_(3)N_(4))作为一种无机非金属材料,是一种很有前景的产H_(2)O_(2)光催化剂。然而,块体g-C_(3)N_(4)存在光生电子空穴复合严重以及光生电荷迁移能力弱等问题,导致其光催化产H_(2)O_(2)效率低。为了提高g-C_(3)N_(4)的光催化产H_(2)O_(2)活性。本文通过简单的连续两步高温煅烧制备了含有碳空位的超薄g-C_(3)N_(4)纳米片(CNS580),通过X射线衍射仪、扫描电子显微镜、原子力显微镜、电子顺磁共振仪、紫外可见漫反射、瞬态光电流、电化学阻抗谱测试等对光催化剂进行了一系列的结构形貌、光吸收性能以及电化学性能表征。结果表明,该光催化剂具有超薄纳米片结构,厚度约为2.15nm,可提高光生电荷的传输效率;同时引入的碳空位可捕获光生电子,这将改善其光生电子空穴的分离能力。在光催化产H_(2)O_(2)的实验中,CNS580光催化反应6h,其产H_(2)O_(2)浓度可达到0.091mmol/L,是块体g-C_(3)N_(4)的4.13倍。此外,讨论并提出CNS580光催化产H_(2)O_(2)可能的机理。

Photocatalytic production of hydrogen peroxide(H_(2)O_(2)),as a green and sustainable technology,has the advantages of clean and pollution-free,safety,low energy consumption and low cost compared with the anthraquinone method commonly used in industry.Graphitic phase carbon nitride(g-C_(3)N_(4)),as an inorganic nonmetallic material,is a promising H_(2)O_(2)producing photocatalyst.However,bulk g-C_(3)N_(4)suffers from severe photogenerated electrons-holes complexation and weak photogenerated charge transfer ability,resulting in its low photocatalytic H_(2)O_(2)production efficiency.In order to improve the photocatalytic H_(2)O_(2)production activity of g-C_(3)N_(4),ultrathin g-C_(3)N_(4)nanosheets containing carbon vacancies(CNS580)were prepared by simple sequential two-step high-temperature calcination in this paper,and the structure and morphology,light absorption properties and electrochemical properties of photocatalysts were characterized by XRD,SEM,AFM,ESR,UV-Vis,TPC and EIS.The results showed that the photocatalyst had an ultrathin nanosheet structure with a thickness of about 2.15nm,which could improve the transmission efficiency of photogenerated charge.Meanwhile,the introduced carbon vacancies could capture photogenerated electrons,which would improve its photogenerated electronsholes separation ability.In the experiment of photocatalytic H_(2)O_(2)production,the H_(2)O_(2)production concentration by CNS580 via photocatalytic reaction for 6h could reach 0.091mmol/L,which was 4.13 times higher than that of the bulk g-C_(3)N_(4).In addition,the possible mechanism of photocatalytic H_(2)O_(2)production for CNS580 was discussed and proposed.