Purbia Rahul, Paria Santanu
Interfaces and Nanomaterials Laboratory, Department of Chemical Engineering, National Institute of Technology, Rourkela 769 008, India.
Dalton Trans. 2017 Jan 17;46(3):890-898. doi: 10.1039/c6dt03723b.
This study reports an easy synthesis protocol of a novel bimetallic silver halide (Au/AgBr-Ag) plasmonic heterostructure as a visible light induced photocatalyst. In this process, first CTAB capped Au NPs were coated with AgBr, and then Ag nanoparticles were formed on the surface of AgBr by photoreduction, while exposing to daylight at room temperature. The presence of Au and Ag improves the visible absorption ability of NPs and avoids charge recombination of the semiconductor AgBr during photoexcitation, which in turn enhances 16 and 8.9 fold the photocatalytic efficiency of Rhodamine B dye degradation under visible light irradiation compared to that of pure AgBr and AgBr/Ag, respectively. The recycling tests of the photocatalyst show only ∼8.7% decrease in efficiency after the 5 cycle of reuse without changing the morphology. During the photocatalytic process, active superoxide radicals (O˙) play a major role, proved through scavenger trapping and photoluminescence experiments. The presence of two plasmonic metals (Au and Ag) in the heterostructure helps to improve visible light absorption as well as avoid charge recombination of the semiconductor AgBr to act as a better photocatalyst. Since this heteronanostructure can be easily synthesized by a one-step method, this study could provide a new approach for the development of efficient bimetallic/semiconductor halide plasmonic photocatalysts with enhanced visible absorption and better charge separation.
本研究报道了一种新型双金属卤化银（Au/AgBr-Ag）等离子体异质结构作为可见光诱导光催化剂的简便合成方案。在此过程中，首先用AgBr包覆十六烷基三甲基溴化铵（CTAB）包覆的金纳米粒子（Au NPs），然后在室温下暴露于日光下通过光还原在AgBr表面形成银纳米粒子。金和银的存在提高了纳米粒子的可见光吸收能力，并避免了光激发过程中半导体AgBr的电荷复合，这反过来又使罗丹明B染料在可见光照射下的光催化降解效率分别比纯AgBr和AgBr/Ag提高了16倍和8.9倍。光催化剂的循环测试表明，在重复使用5次后效率仅下降约8.7%，且形态未发生变化。在光催化过程中，活性超氧自由基（O˙）起主要作用，这通过清除剂捕获和光致发光实验得到证实。异质结构中两种等离子体金属（金和银）的存在有助于提高可见光吸收，并避免半导体AgBr的电荷复合，从而成为更好的光催化剂。由于这种异质纳米结构可以通过一步法轻松合成，本研究可为开发具有增强可见光吸收和更好电荷分离性能的高效双金属/半导体卤化物等离子体光催化剂提供一种新方法。
