高活性BiOI/g-C_(3)N_(4)光催化剂的合成及性能提高机制

Synthesis and Performance Enhancement Mechanis of BiOI/g-C_(3)N_(4) Photocatalyst with High Activity

稳定高效光催化剂的合成是光催化技术的关键。本工作采用原位沉积法构建了不同质量比的BiOI/CNx复合材料。结果表明,与BiOI的复合未影响g-C_(3)N_(4)的晶体结构,复合产物中晶型BiOI紧密附着在片层g-C_(3)N_(4)表面,BiOI的引入使禁带宽度明显减小,对可见光的吸收能力也显著增强,BiOI/CNx中光生电子-空穴的寿命随BiOI复合量的增加而逐渐延长。BiOI/CN15对罗丹明(RhB)具有最强的吸附能力和光催化活性,暗反应30 min时的吸附率达到55.15%,为同等条件下g-C_(3)N_(4)的2.68倍;光降解10 min时的降解率为87.69%,是相同条件下g-C_(3)N_(4)的1.9倍;其催化反应速率常数为5.551×10^(-2)min^(-1),循环使用五次后降解率仅下降4.5%,具有良好的光催化稳定性。BiOI与g-C_(3)N_(4)复合后有利于光生电子空穴对的有效分离和电子在界面之间的快速转移,在BiOI/CN15复合光催化剂降解RhB的过程中,h^(+)和·O_(2)^(-)是主要发挥作用的活性物质。

The synthesis of stable and efficient photocatalysts is the key of photocatalysis technology. Thiswork uses the situ deposition method to construct diverse mass ratio BiOI/CN x series of composite materials, which composited with BiOI doesn’t influence the crystal structure of g-C_(3)N_(4). In addition, the crystal form BiOI from composite products is closely adhered to the surface of lamellar g-C_(3)N_(4). The introduction of BiOI obviously decreases band gap and availably increases the absorption of visible light. Meanwhile, the service life of photoproduction electron-holes gradually strengthens with the compound quantity of BiOI increasing. BiOI/CN15 has the strongest adsorption capacity and photocatalytic activity for RhB. Therefore, the absorption rate of g-C_(3)N_(4) reached 55.15% under dark reaction for 30 minutes, which is 2.68 times than g-C_(3)N_(4) in the same condition. The degradation rate of g-C_(3)N_(4) was 87.69% at 10 minutes of photodegradation, which is 1.9 times than g-C_(3)N_(4) in the same condition. The catalytic reaction rate constant is 5.551×10^(-2) min^(-1) . And the degradation rate only decreased by 4.5% after five recycles, which owns good stability of photocatalyst. The combination of BiOI and g-C_(3)N_(4) is beneficial to the effective separation of photogenic electron-holes pairs and the rapid transfer of electrons between interfaces. In the degradation of RhB by BiOI/CN15 composite photocatalyst, h^(+) and ·O_(2)^(-) are the main active substances.