A Win–Win Strategy to Fabricate Double Z‑Scheme\nSelf-Supporting Integrated Photoelectrode Derived from Aniline Wastewater\nfor Synthesis of H<sub>2</sub>O<sub>2</sub> and Recovery of Polyaniline

H<sub>2</sub>O<sub>2</sub> and polyaniline (PANI) are important\nchemicals in the chemical and manufacturing industries. Herein, the\nconcept of “turning waste into treasure” was proposed:\nPANI derived from aniline (ANI) wastewater was used to fabricate a\ndouble Z-scheme NiFe<sub>2</sub>O<sub>4</sub>–O<sub>v</sub>@CdS@PANI photoelectrocatalytic catalyst for alleviating environmental\npollution and producing H<sub>2</sub>O<sub>2</sub>. The double Z-scheme\nself-supporting integrated photoelectrode enables high light utilization\nand an excellent redox ability. In addition, the further designed\nJanus “floating” photocathode can efficiently entrap\nO<sub>2</sub> from the air and afford unidirectional transportation\nof O<sub>2</sub> from the gas-collecting side to the catalyst side\nduring the O<sub>2</sub> reduction reaction. The H<sub>2</sub>O<sub>2</sub> yield obtained using the Janus “floating” photocathode\n(264.52 mg·L<sup>–1</sup>·h<sup>–1</sup>)\nis 7.2 times higher than those of conventional “submerged”\nelectrodes. By coupling the ANI polymerization reaction with the H<sub>2</sub>O<sub>2</sub> production, the assembled electrolyzer exhibits\na low cell voltage of 1.3 V vs Ag/AgCl to drive the integrated two\nhalf-reactions, the recovery rate of ANI reaches 96.5%, and the yield\nof H<sub>2</sub>O<sub>2</sub> reached 41.9 mg·L<sup>–1</sup> (1.3 V vs Ag/AgCl) in solution with ANI, nearly 3 times the yield\nin solution without ANI.