Wang Cong, Wang Guanlong, Zhang Xiufang, Dong Xiaoli, Ma Chun, Zhang Xinxin, Ma Hongchao, Xue Mang
School of Light Industry and Chemical Engineering, Dalian Polytechnic University Dalian China 116034
RSC Adv. 2018 May 21;8(33):18419-18426. doi: 10.1039/c8ra02882f. eCollection 2018 May 17.
Photocatalysis has been regarded as an attractive strategy for the elimination of contaminants, but its performance is usually limited by the fast recombination of photogenerated electron-holes. A heterojunction photocatalyst could achieve the effective separation of electron-holes. However, the electrons migrate to the less negative band while holes move to the less positive band, leading to a weakened redox ability. Z-scheme photocatalysis is a feasible way to realize the efficient separation of photogenerated electron-holes without sacrificing the reductive ability of electrons and oxidative ability of holes. In this work, a new Z-scheme photocatalyst, composed of g-CN (photocatalyst I), FeWO (photocatalyst II) and RGO (electron mediator), was fabricated through a facile hydrothermal and mixing method. The effect of contact ways (the electron mediator firstly combined with photocatalyst I or with photocatalyst II) on the Z-scheme photocatalytic performance was investigated. The photocatalytic removal rate of rhodamine B (RhB) was largely enhanced by the construction of a Z-scheme photocatalyst, compared with the g-CN/FeWO composite without RGO. The contact ways could affect the photocatalytic ability of a Z-scheme photocatalyst. The enhanced photocatalytic performance was attributed to the Z-scheme induced efficient separation of photogenerated charge carriers. Furthermore, remaining holes (on the VB of FeWO) or remaining electrons (on the CB of g-CN) with powerful oxidation or reduction ability would promote the photocatalytic degradation of RhB.
光催化被认为是一种去除污染物的有吸引力的策略，但其性能通常受到光生电子 - 空穴快速复合的限制。异质结光催化剂可以实现电子 - 空穴的有效分离。然而，电子迁移到负性较小的能带，而空穴迁移到正性较小的能带，导致氧化还原能力减弱。Z型光催化是一种在不牺牲电子还原能力和空穴氧化能力的情况下实现光生电子 - 空穴高效分离的可行方法。在这项工作中，通过简便的水热和混合方法制备了一种由g-CN（光催化剂I）、FeWO（光催化剂II）和RGO（电子介质）组成的新型Z型光催化剂。研究了接触方式（电子介质首先与光催化剂I或光催化剂II结合）对Z型光催化性能的影响。与不含RGO的g-CN/FeWO复合材料相比，Z型光催化剂的构建大大提高了罗丹明B（RhB）的光催化去除率。接触方式会影响Z型光催化剂的光催化能力。光催化性能的提高归因于Z型结构诱导的光生电荷载流子的有效分离。此外，具有强大氧化或还原能力的剩余空穴（在FeWO的价带上）或剩余电子（在g-CN的导带上）会促进RhB的光催化降解。
