Erandi Prangige is currently a PhD student at Science and Engineering Faculty, Queensland University of Technology, Australia under the guidance of Prof Huaiyong Zhu. Her research interests include finding new insights into visible-light photocatalysts for fine organic synthesis, with noble metal nanoparticles and their alloy nanoparticles.
Photocatalysis is an intriguing phenomenon in the realm of green chemical sciences, as it combines the efficiency of catalysis with the use of solar energy. In this study, we developed a highly efficient alloy nanoparticles (NPs) of Au and Co (Au:Co 2:1 wt % ratio) supported on ZrO2 that have photo switchable product selectivity under light and dark conditions. Hydroamination of alkyne reaction is considered as the model reaction. It is worthwhile to notice that, on Au-Co alloy NPs surface, imine (cross-coupling product) of alkyne and aniline is dominant (95 %) in photo reaction while the homo-coupling of alkyne is the major product (90 %) in dark reactions. However, when monometallic Au NPs are used as the catalyst, similar product selectivity is achieved in both dark and light with much lower conversion rates. These evidences demonstrated that the reaction pathway of hydroamination of alkyne is tuneable by switching on and off the light on Au-Co alloy surface. Suggested two morphologies for the alloy NP surface are; (1) Aniline molecules have a weak adsorption to the catalyst in dark, therefore, homocoupling of alkyne is more dominant. (2) Alloy has two types of adsorption sites which are specific to different molecules and active sites specific to aniline is only active in light.
Audience Take away:
• Au-Co alloy NPs on ZrO2 can activate the alkyne hydroamination reactions with super eminent activity under visible light irradiation: 99 % conversion and 95 % selectivity.
• The difference in product selectivity under dark and light conditions provide a novel insight into catalytic mechanism.
• Results evidenced a good feasibility on a range of substituent groups with electron withdrawing and electron donating substituents.