BiFeO3 shows promising applications in photocatalytic degradation, purification process, and in clean energy generation. The various fascinating properties of bismuth ferrite nanoparticles can be improved by doping the material at either of the A or B sites to give it extra photocatalytic advantage toward decreasing the energy bandgap and other photophysical properties of the material. In this research, pure Bi0.65K0.2Ba0.15FeO3 perovskite material was synthesized using the sol-gel method via citric acid route in the presence of sodium dodecyl sulfate (SDS). The powdered nanoparticles were annealed at different annealing temperatures of 600, 700, and 800 °C each for 4 h in a muffle furnace and coded K2BFO 600, K2BFO 700, and K2BFO 800 corresponding to the annealing temperature of each portion. The powder nanoparticles were characterized using powdered X-ray diffraction (PXRD) to determine the crystallite structure. The samples displayed similar peak patterns with increase in intensity as the annealing temperature is increased indicating an increase in crystallinity. The impurity peaks in K2BFO 800, however, show that the sample may contain a secondary phase. Scanning electron microscopy (SEM) was used to determine the morphology, and UV-Vis spectroscopy indicated that all the powders were photoactive within the visible region of the electromagnetic spectrum. ATR-FTIR spectra of the samples were collected to study the formation and phase purity of the B-site in the perovskite structures. The photocatalytic performance of the powder was tested on methylene blue dye under visible light irradiation for the degradation studies. All powders showed photocatalytic ability after 2 h of irradiation with the powder annealed at 800 °C being better. The photocatalytic activities of the powders showed improvement on addition of 2 drops of 1 M H2O2 (80% degradation for K2BFO 800). The bandgap energy of K2BFO 800, 700, and 600 was estimated at approximately 2.00, 2.12, and 2.18 eV, respectively, using Tauc’s equation. The improved activity is as a result of photoabsorption of visible light by the doped powders causing generation of electrons and holes. The kinetic studies were carried out and the mechanisms of the photocatalytic reaction proposed. The effect of annealing temperature on synthesis of the material shows enhanced photoactivity in the presence of hydrogen peroxide leading to improved performance for the degradation of MB, and the catalyst can be said to be a good candidate for the treatment of waste materials.

中文翻译：

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退火温度对溶胶-凝胶法合成Bi0.65K0.2Ba0.15FeO3类钙钛矿纳米粒子合成及光催化性能的影响

BiFeO3 在光催化降解、净化过程和清洁能源生产中具有广阔的应用前景。铋铁氧体纳米粒子的各种迷人特性可以通过在 A 或 B 位点掺杂材料来改善，以赋予其额外的光催化优势，以降低材料的能带隙和其他光物理特性。在本研究中，在十二烷基硫酸钠 (SDS) 存在下，通过柠檬酸途径使用溶胶-凝胶法合成了纯 Bi0.65K0.2Ba0.15FeO3 钙钛矿材料。将粉末状纳米粒子在马弗炉中分别在 600、700 和 800 °C 的不同退火温度下退火 4 小时，并编码 K2BFO 600、K2BFO 700 和 K2BFO 800，对应于每个部分的退火温度。使用粉末 X 射线衍射 (PXRD) 表征粉末纳米粒子以确定微晶结构。随着退火温度的增加，样品显示出类似的峰模式，强度增加，表明结晶度增加。然而，K2BFO 800 中的杂质峰表明样品可能含有第二相。使用扫描电子显微镜 (SEM) 来确定形态，UV-Vis 光谱表明所有粉末在电磁光谱的可见光区域内都具有光活性。收集样品的 ATR-FTIR 光谱以研究钙钛矿结构中 B 位点的形成和相纯度。在可见光照射下对亚甲基蓝染料测试粉末的光催化性能以进行降解研究。所有粉末在照射 2 小时后均表现出光催化能力，其中在 800°C 下退火的粉末效果更好。添加 2 滴 1 M H2O2（K2BFO 800 降解 80%）后，粉末的光催化活性得到改善。使用 Tauc 方程估计 K2BFO 800、700 和 600 的带隙能量分别约为 2.00、2.12 和 2.18 eV。提高的活性是掺杂粉末对可见光的光吸收导致电子和空穴的产生的结果。进行了动力学研究并提出了光催化反应的机理。退火温度对材料合成的影响在过氧化氢存在下显示出增强的光活性，从而提高了降解 MB 的性能，