The efficient removal of ammonia is a difficult issue in wastewater treatment because ammonia is easily converted to nitrate instead of N₂. The oxidation of ammonia by chlorine radical (Cl•) is recognized as an effective method. However, the massive generation of toxic byproducts chlorate and nitrate pose great risk for its practical application due to the excessive oxidation capacity of hydroxyl radical. Herein, we propose a novel method to selectively generate Cl• for efficient ammonia removal using BiVO₄/WO₃ photoanode in a self-driven photoelectrocatalytic (PEC) system. Cl• was predominantly produced by regulating the valence band edge of WO₃ though modifying BiVO₄, which tuned the moderate oxidative force of hole to reduce OH• generation and thereby inhibited the formation of chlorate and nitrate. The self-driven ammonia degradation was achieved by employing BiVO₄/WO₃ and Si photovoltaic cells as composite photoanodes to improve light-absorption and electron-hole separation, thus enhancing Cl• production. These results showed that 10 mg L^-1 of ammonia-N was completely removed (99.3%) in 120 min with 80.1% of total nitrogen removal. Toxic byproducts chlorate and nitrate were inhibited by 79.3% and 31%, respectively, compared to WO₃. This work provides new insights to develop efficient, energy-saving and environment-friendly method for ammonia pollution treatment.

在废水处理中，有效去除氨是一个难题，因为氨很容易转化为硝酸盐而不是N ₂。氯自由基（Cl•）氧化氨被认为是一种有效的方法。然而，由于羟基自由基的过度氧化能力，大量产生的有毒副产物氯酸盐和硝酸盐对其实际应用构成很大的风险。在本文中，我们提出了一种新方法，可在自驱动光电催化（PEC）系统中使用BiVO ₄ / WO ₃光电阳极选择性生成Cl•以有效去除氨。Cl•主要是通过修饰BiVO ₄来调节WO ₃的价带边缘而产生的。，它调节了孔的适度氧化力，以减少OH•的生成，从而抑制了氯酸盐和硝酸盐的形成。通过将BiVO ₄ / WO ₃和Si光伏电池用作复合光阳极来改善光吸收和电子-空穴分离，从而提高Cl•的产生，实现了自驱动氨降解。这些结果表明，在120分钟内10 mg L ^-1的氨氮被完全去除（99.3％），而总氮的去除率为80.1％。与WO ₃相比，有毒副产物氯酸盐和硝酸盐分别被抑制79.3％和31％。这项工作为开发高效，节能和环保的氨污染处理方法提供了新见识。