Tuning the photocatalytic activity of graphene quantum dots via decorating the X% (Co3O4) as modern photocatalysts to produce ammonia

• Published in: Journal of molecular liquids 2023-12, Vol.391, p.123223, Article 123223
• Main Authors: Mokhtari, A., Khatamian, M.
• Format: Article
• Language: English
• Subjects: Ammonia production; Co3O4 nanoparticles; Graphene quantum dots; NH3 photofixation; Photocatalyst
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2023.123223

[Display omitted] •The facile and outstanding route were introduced for decorating Co3O4 on GQDs to form the X% (Co3O4)/GQDs composites.•The Co3O4 nanoparticles with ultra-small sizes were uniformly decorated on the GQDs.•The resultant composites are applied as the robust photocatalysts for the conversion of N2 to NH3.•The kinetics and the concentration of produced ammonia on the surface of X% (Co3O4)/GQDs composites were studied in details.•The mechanism of ammonia production is discussed in details. The crises related to energy and pollutants in the present century have led to the special look toward clean and sustainable energies. Material science plays a significant role in the way to achieve the world’s envisioned sustainability. This paper introduces an outstanding and facile route for decorating cobalt oxide (Co3O4) on graphene quantum dots (GQDs) to form the X% (Co3O4)/GQDs composites. The 5% Co3O4/GQDs, 10% Co3O4/GQDs, and 20% Co3O4/GQDs composites are formed with the aid of ultrasound irradiation, followed by the pyrolysis of citric acid employing a bottom-up approach. Decoration of Co3O4 nanoparticles with various weight percentages of 5%, 10%, and 20% is uniformly performed into the GQDs with the size distribution of 4.4, 4.6, and 4.8 nm, respectively. The resultant composites are applied as the robust photocatalysts for the conversion of N2 to NH3. In this report, GQDs decorated by three ratios of 5%, 10%, and 20% of Co3O4 are formed to evaluate the effect of decorated Co3O4 weight percentage on the production of ammonia. In addition, the kinetics and the concentration of the produced ammonia are studied using these composites. Based on the comparative analysis, the 5% Co3O4/GQDs photocatalyst not only optimizes the production of ammonia related to 10% Co3O4/GQDs, and 20% Co3O4/GQDs photocatalysts but also indicates the faster kinetics of ammonia production. These results can be attributed to the more uniform distribution and the lower size of nanoparticles in 5% Co3O4/GQDs photocatalyst.