Peroxydisulfate (PDS) can be activated by electrochemistry, for which using atom H* as an activator is feasibly favorable in theoretical and experimental applications. Studies have shown that atomic H* can cleave the peroxide bond as a single-electron reducing agent in Na2S2O8 to generate SO4•−, thus achieving the degradation of pollutants. Herein, Pd nanoparticles synthesized by in an in situ solution were dispersed in carbon black and then loaded on carbon felt, called Pd/C@CF, as the cathode for peroxydisulfate activation. This showed an ideal degradation effect on a small electrode (10 mm × 10 mm). Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) tests were taken to verify the significant increase in the yield of the reduction of Na2S2O8 by H*. The degradation experiments and free-radical scavenging experiment confirmed that the atomic H* was the dominant component triggering the activation of PDS to generate SO4•−. A Pd/C@CF composite electrodes have low pH dependence, high stability and recyclability, etc., which has many potential practical applications in wastewater treatment. In addition, H* can also reduce H2O2 to •OH by breaking the peroxide bond, so the removal of pollutants by the same amount of H2O2 and Na2S2O8 under the same conditions is compared, and their application prospects are analyzed and compared.

The presence of organics in water poses a serious risk to the environment, as well as to human health. It is important to develop effective water treatment techniques that are affordable, durable, and sustainable. The removal and degradation of organic matter in water is widely explored using 2D and 3D nanomaterials, which are advantageous in providing high surface to volume ratios and favorably photoelectro activity as compared to traditional materials. The robustness of nano semiconductors has made it highly sustainable in water treatment. This review concentrates on nanostructured materials, which are demonstrating the removal of pollutants from water using various 2D and 3D nanostructured materials as photoelectrocatalytic electrodes. The 2D and 3D nanostructured materials are divided into five types according to physical morphology: nanofilms/nanosheets, nanopore structure/nanonetwork, nanoflowers, nanotubes, and other forms. Apart from this, the preparation method, characterization technology, and photoelectrocatalytic efficiency of organic pollutants degradation are reviewed. Finally, the different factors influencing degradation of organic pollutants are discussed.

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