g-C3N4 doping TiO2 recovered from spent catalyst for H2 evolution from water
Xiaoqing Jing, Yan Zhang, Weiting Yang, Qing Liu, Huaqing Zhao, Hongbo Xie, Wenqi Wang, Mingzhi Zhang, Haita Lu, Stephen Nyabire Akanyange, Xiutong Wang, John C. Crittenden, Xianjun Lyu, Hui Chang
Abstract
Spent catalysts of selective catalytic reduction (SCR) contain a high content of TiO 2 (>70 wt%). The effective recovery of TiO 2 from spent SCR catalysts and its reuse in photocatalytic hydrogen production is of great importance for environmental protection. In this study, the recovered TiO 2 from the spent SCR catalyst was recovered by the alkali washing method, and the purity of the recovered TiO 2 reached 94.7%. g-C 3 N 4 as a co-catalyst and enhanced the separation efficiency of the photogenerated electron-hole pairs of the TiO 2 photocatalyst . The composite photocatalyst R–TiO 2 /g-C 3 N 4 prepared by directly mixing the recovered TiO 2 with g-C 3 N 4 significantly improved the photocatalytic activity . The experimental design of the photocatalyst synthesis was optimized using the Design Expert software. The results showed that the recovered TiO 2 was 0.334 g when the g-C 3 N 4 was 0.046 g and the ultrasonic time was 163 min. Moreover, the hydrogen production rate reached 443.105 μmol g −1 h −1 within 4 h.