Key Role of Corncob Based-Hydrochar (HC) in the Enhancement of Visible Light Photocatalytic Degradation of 2,4-Dichlorophenoxyacetic Acid Using a Derivative of ZnBi-Layered Double Hydroxides

Abstract

A superior heterojunction of HC-ZnBi-LDO was synthesized in two steps, namely hydrothermal carbonization, followed by co-precipitation. The 2% HC-ZnBi-LDO heterojunction photocatalysts could degrade over 90.8% of 30 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) using 1.0 g/L of the catalyst after 135 min of visible light exposure at pH 4. The activity of 2% HC-ZnO-LDO was remarkably stable. Approximately 86.4–90.8% of 30 mg/L 2,4-D was degraded, and more than 79–86.4% of TOC was mineralized by 2% HC-ZnBi-LDO at pH 4 after 135 min of visible light exposure during four consecutive cycles. The rapid separation and migration of charge carriers at the interfaces between HC and ZnBi-LDO were achieved within 2% HC-ZnBi-LDO. Moreover, the electron acceptor characteristic of HC in 2% HC-ZnBi-LDO caused the recombination of charge carriers to decrease significantly, thus generating more reactive radicals, such as hydroxyl radicals (OH●) and superoxide radicals (O2●−). These results demonstrate that the novel 2% HC-ZnBi-LDO is a superior photocatalyst for the remediation of hazardous organic pollutants.

Eco-Friendly Coffee Waste-Based Carbon Dots Coupled to ZnBi-Layered Double Hydroxide Heterojunction: Enhanced Control of Interfacial Charge Transfer for Highly Efficient Visible-Light Catalytic Activity

“…It would be a better choice to combine ZnBi 2 O 4 with other functional materials to improve the separation of photogenerated e − /h + pairs and enhance the surface charge transfer efciency. ZnBi 2 O 4 has been combined with many diferent semiconductors such as g-C 3 N 4 [27,28], Bi 2 S 3 [29], graphite [30], ZnO [31], reduced graphene oxide [32], ZnS [33], and hydrochar [34] to remove toxic organic contaminants. Although these strategies improve the separation efciency of e − /h + pairs to some extent, these catalysts are still insufcient for potential industrial applications.…”