Investigating the effect of AuCu2-xSe Nanoparticle on Photocatalytic Nitrogen Fixation (PNF)

Abstract

Ammonia’s significance as a compound spans across various applications from the making of fertilisers in food production to different industries. Conventionally, ammonia has been industrially produced through the Haber-Bosch process, which has led to 1.6% of total  global carbon dioxide emissions proving it to not be eco-friendly. Photocatalytic Nitrogen Fixation (PNF) has emerged as one of the key eco-friendly methods to produce ammonia through the passage of nitrogen. In order to appeal to human needs though, PNF has to be enhanced to make it faster, efficient, and produce more ammonia to sustain our population. In this research, we aim to figure out whether the Copper Selenide doped Gold nanoparticle (AuCu2-xSe) can be an effective method to enhance PNF catalytically. We first synthesised the nanoparticle by adding 500 μl of the already prepared Au nanoparticle to 1 ml of 5 mM hexadecyltrimethylammonium
bromide (CTAB) to stabilise the dumbbell-shaped nanoparticle. Then, we added 50 μl of Selenium Oxide and 100 μl of 0.1 mol Ascorbic Acid. Once we centrifuged the solution, we further added 1.5 ml of CTAB, 10 μl of 0.2 mol copper sulphate (CuSO4) and 100 μl of 0.1 mol Ascorbic Acid and ensured the formation of AuCu2-xSe nanoparticle by visualising through the TEM microscope. Then, we set up a glass reactor with the nanoparticle and performed PNF by passing nitrogen gas while maintaining a stable temperature. We took out the solution from the glass reactor every 2 hours and measured the concentration of ammonia through 2 tests: adding Nessler’s Reagent and Indophenol-blue solution. Through a UV-vis spectrophotometer, we obtained the absorbance level of this solution. We compared this solution with a calibration curve obtained from a set of known concentrations of NH4Cl to calculate the concentration of ammonia. Through the results, we imply that the AuCu2-xSe nanoparticle could be effective in enhancing the process of PNF.