In-situ structuring a robust cellulose hydrogel with ZnO/SiO heterojunctions for efficient photocatalytic degradation.

Hydrogel supported photocatalyst, an efficient strategy for water remediation suffers from compromised catalytic activity and insufficient stability. Herein, a robust cellulose-based composite hydrogel with zinc oxide (ZnO)/silica (SiO) heterojunctions were fabricated by in-situ synthesis, where SiO not only acted as a cross-linking agent to enhance the mechanical strength and stability of hydrogel, but also promoted the photocatalytic properties of ZnO via transferring the electron-hole pairs due to its surface state. As a result, a significant improvement in the mechanical properties of cellulose-based composite hydrogel was achieved, exhibiting a high compressive strength of 703.4 kPa. Moreover, the degradation efficiency of methylene blue (MB) under light irradiation by cellulose-based composite hydrogel was 95 % in 120 min and the removal ratio maintained as high as 90 % after eight degradation cycles. This study provides a low-cost and facile method to construct new hydrogel supports with high stability and efficient photocatalytic properties.