A self-modified Bi₂SiO₅/Bi₁₂SiO₂₀ heterojunction was synthesized for the first time via a citric acid-assisted hydrothermal method. It was found that citric acid (CA) played two roles in the formation of the Bi₂SiO₅/Bi₁₂SiO₂₀ heterojunction: enhancement of the specific surface area due to the release of many volatiles from the decomposition of CA and tuning the weight ratio of Bi₂SiO₅ and Bi₁₂SiO₂₀ in the heterojunction by forming different complexes with Bi³⁺. Thus, a self-modified Bi₂SiO₅/Bi₁₂SiO₂₀ heterojunction prepared at a CA dosage of 11.25 mmol presented an I_27.9 : I_29.2 value of 1.52 and a BET specific surface area of 32.6 m² g⁻¹, 5.7 times that without addition of CA. It showed the highest first-order apparent reaction constant of 0.1694 min⁻¹ in the photocatalytic degradation of acid orange 7 (AO7), which is 1.8, 53.0, and 2.2 times that of Bi₂SiO₅, Bi₁₂SiO₂₀, and TiO₂ (P25), respectively. The capture experiments show that the main active species that degraded AO7 are not O₂˙⁻ and ˙OH but h⁺_vb. During the AO7 degradation, four intermediates, sulfonic acid, oxalic acid, benzenesulfonic acid, and 4-aminobenzenesulfonic acid, were identified by capillary electrophoresis/capacitively coupled contactless conductivity detection. Finally, other pollutants, rhodamine B, p-chlorophenol, and tetracycline, were also found to be efficiently removed by the Bi₂SiO₅/Bi₁₂SiO₂₀-mediated photocatalysis system.

中文翻译：

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柠檬酸辅助水热合成自改性的Bi ₂ SiO ₅ / Bi ₁₂ SiO ₂₀异质结，有效地光催化降解水性污染物

通过柠檬酸辅助水热法首次合成了自修饰的Bi ₂ SiO ₅ / Bi ₁₂ SiO ₂₀异质结。发现柠檬酸（CA）在Bi ₂ SiO ₅ / Bi ₁₂ SiO ₂₀异质结的形成中起着两个作用：由于CA分解过程中释放出许多挥发物而导致比表面积的增加以及重量的调整通过与Bi ³⁺形成不同的配合物，异质结中Bi ₂ SiO ₅和Bi ₁₂ SiO _20的比率。因此，以11.25mmol的CA剂量制备的自改性的Bi ₂ SiO ₅ / Bi ₁₂ SiO ₂₀异质结的I _27.9  ：  I _29.2值为1.52，BET比表面积为32.6 m ² g ^-1，是5.7倍没有添加CA的情况。在酸性橙7（AO7）的光催化降解中，其最高一级表观反应常数为0.1694 min ^-1，是Bi ₂ SiO ₅，Bi ₁₂ SiO ₂₀和TiO的1.8、53.0和2.2倍。_2个（P25）。捕获实验表明，该降解AO7的主要活性物质不是Ø ₂ ˙ ^-呵呵除H ⁺ _VB。在AO7降解过程中，通过毛细管电泳/电容耦合非接触电导检测法鉴定了四个中间体，即磺酸，草酸，苯磺酸和4-氨基苯磺酸。最后，还发现通过Bi ₂ SiO ₅ / Bi ₁₂ SiO ₂₀介导的光催化系统可有效去除其他污染物，若丹明B，对氯苯酚和四环素。