A two-in-one strategy to enhance intrinsic activity and accessibility of active sites of Ag3PO4-based photocatalysts for degrading environmental pollutants

Abstract

Intrinsic activity and accessibility of active sites are two fundamental descriptors for enhancing Ag₃PO₄-based photocatalysts. However, simultaneously optimizing both parameters poses a significant challenge for Ag₃PO₄-based heterojunction photocatalysts prepared by a conventional ion exchange precipitation method. This study demonstrates that Ag₃PO₄/In₂O₃ Z-scheme heterojunction prepared by pre-fabrication and post calcination method not only increases the electron transfer rate (boosts intrinsic activity) by introducing oxygen vacancies and constructing heterojunctions, but also obtains highly dispersed Ag₃PO₄ particles on the surface of hollow tubular In₂O₃ after calcination treatment (enhances accessibility of active sites). Remarkably, the optimized Ag₃PO₄/In₂O₃-2 Z-scheme heterojunction demonstrates an exceptional catalytic efficiency (0.113 min⁻¹) in facilitating the photocatalytic decomposition of tetracycline (TC), significantly outperforming the catalyst synthesized via the conventional ion exchange precipitation technique (0.036 min⁻¹). In addition, three-dimensional excitation emission matrix fluorescence spectroscopy, high-resolution mass spectrometry, photoelectrochemical testing, free radical capture experiments, and electron spin resonance techniques were conducted to elucidate the possible degradation pathways for TC. Importantly, a systematic investigation was conducted to assess the practical application potential of Ag₃PO₄/In₂O₃-2 composites, encompassing the degradation activity in actual wastewater, different dyes and antibiotics, as well as the calculation of toxicity of degradation products and exploration of antibacterial activity. This study provides a “two-in-one” strategy from the perspective of synchronously enhancing the intrinsic activity of catalysts and the accessibility of active sites.