Exploitation of a Poly Acrylic Acid-Fe³⁺ Hydrogel Photocatalyst with Homogeneous and Heterogeneous Features for the Efficient Removal of Organic Pollutants

Photocatalysis provides a possibility of fully degrading organic pollutants from wastewater; however, traditional semiconductor photocatalysts are restricted by poor adsorption properties, limited utilization of light energy, loss of the catalyst, and secondary pollution. In this work, a transparent poly acrylic acid-Fe3+ (PAA-Fe3+) hydrogel with homogeneous and heterogeneous catalytic features and excellent photocatalytic performance was herein smartly constructed through a facile one-step synthesis approach. Experimental and theoretical calculation results verify that the introduced Fe3+ ions coordinate with −COOH (L) functional groups on the chain of PAA to form complex [FeL6]3+ ions, which not only improve the mechanical property of the PAA hydrogel but also act as photocatalytic active sites with homogeneous features to efficiently degrade photoinduced-enriched pollutant molecules (MB: 96% in 40 min). The photocatalytic behavior of PAA-Fe3+ is suggested according to the molecular orbital theory of the complex, and active species are captured and •OH/h+ are demonstrated to be the main active substances in the photocatalytic process.