pH对水热合成红磷晶体及其光催化性能的影响

以商业红磷（C-RP）为原料,NaOH溶液为调节剂,采用水热法处理C-RP获得HRP-pHx（x=5,7,9）光催化剂。选择罗丹明B （RhB）为降解对象考察HRP-pHx的光催化活性,其中HRP-pH7展现出最高的光催化活性,对RhB的降解速率常数为3.1×10^-2,是未调pH水热处理所得HRP的2.8倍。结果表明,调节pH增强RP光催化活性的主要机理是均匀的结构和较小的粒径使得HRP-pH7比HRP具有更多的活性位点。循环光降解实验结果发现HRP-pH7循环降解RhB五次后的降解率仍大于92%,体现了较好的稳定性。捕获剂实验发现光降解中起主要作用的是光生空穴和超氧基自由基。

Effects of pH on hydrothermal synthesis of red phosphorus crystals and their photocatalytic activity

With commercial red phosphorus (C-RP) as the raw material and NaOH as the regulator, the HRP-pHx (x=5, 7, 9) photocatalyst was obtained by hydrothermal treatment. The photocatalytic activity of HRP-pHx was evaluated by photodegrading Rhodamine B (RhB), in which HRP-pH7 manifested the highest photocatalytic activity. Its rate constant for RhB was 3.1×10^-2, which was 2.8 times that of HRP. The series characterization results showed that the main reason for the RP photocatalytic activity enhanced by adjusting pH is that the uniform structure and the smaller particle size make HRP-pH7 have more active sites than HRP. The repeated experiments indicated that HRP-pH7 was a stable photocatalyst for degrading RhB (the degradation rate was over 92% for reusing the catalyst the fourth time). In active species trapping experiments it was found that the photogenerated holes and superoxide free radicals played a main role in degrading RhB.