The activity of heterogeneous photocatalyst largely depends on its surface properties, especially the dispersibility, hydrophilicity and surface charge of the photocatalyst. Cellulose nanocrystal (CNC) is a renewable biomass material with abundant polar functional groups, which can be attached to the surface of photocatalyst to regulate its surface properties. Herein, lantern-like BiOBr/CNC composites, in which CNCs were used as a surface modifier, were in-situ fabricated under ambient temperature with a simple wet-chemical method. The surface charges of CNCs were opposite to that of BiOBr, and it can be attached to the surface of BiOBr by electrostatic attraction to change its surface properties. BiOBr/CNC composites with negatively charged was favorable for the adsorption of Rhodamine B (RhB) cationic dye to its surface. Moreover, the polar groups with –OH and –SO₃H on the CNCs act on the dispersity and hydrophilicity of the photocatalyst, and the photocatalyst particles can be well dispersed in aqueous solution, thus improving the photocatalytic degradation performance of RhB. The strategy to adjust the dispersibility, hydrophilicity and surface charge of materials by CNCs as a modifier is expected to apply in the surface modification to enhance the photocatalytic performance.

Graphic abstract

中文翻译：

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纤维素纳米晶改性BiOBr以提高可见光下的光催化性能

多相光催化剂的活性很大程度上取决于其表面性质，尤其是光催化剂的分散性、亲水性和表面电荷。纤维素纳米晶（CNC）是一种具有丰富极性官能团的可再生生物质材料，可以附着在光催化剂的表面以调节其表面性质。在此，采用简单的湿化学方法在环境温度下原位制备了灯笼状 BiOBr/CNC 复合材料，其中 CNC 用作表面改性剂。CNCs的表面电荷与BiOBr相反，可以通过静电引力附着在BiOBr表面上，改变其表面性质。带负电荷的 BiOBr/CNC 复合材料有利于罗丹明 B (RhB) 阳离子染料吸附到其表面。而且，CNCs 上的₃ H 作用于光催化剂的分散性和亲水性，使光催化剂颗粒能够很好地分散在水溶液中，从而提高 RhB 的光催化降解性能。CNCs作为改性剂调节材料的分散性、亲水性和表面电荷的策略有望应用于表面改性以提高光催化性能。

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