Synthesis and characterization of Black Au nanoparticles deposited over g-C₃N₄ nanosheets: enhanced photocatalytic degradation of methylene blue

ABSTRACT

Black AuNPs, prepared by a facile seeding growth method under ambient conditions, displayed efficient broadband absorption of the incident light over the entire visible and near-infrared regions of the solar spectrum. The spherical black AuNPs with the size of 2–4 nm were deposited over mesoporous g-C₃N₄ nanosheets. Novel black AuNPs/g-C₃N₄ plasmonic photocatalysts were used to remove methylene blue (MB) dye from an aqueous solution. The degradation efficiency for the optimal coupling of 1.3 wt.% black AuNPs with g-C₃N₄ (1.2 g) was found to be 85% within 60 min under visible light irradiation. The calculated kinetic constant was 0.0186 min⁻¹ which was 6.4 and 2.9 times greater than those for g-C₃N₄ and AuNPs/g-C₃N₄ nanocomposite, respectively. The excellent potential in photocatalysis was attributed to the synergistic interactions of the g-C₃N₄ conduction band and the localized surface plasmon resonance effect of black AuNPs. These properties were responsible for the generation of high-energy electrons, a negative shift in the Fermi level of black AuNPs, and the migration of charge carriers. This work studied a new insight into black gold nanoparticles via the design of a visible-light-driven photocatalyst and provided a perspective on valuable photo-related applications such as water treatment.

GRAPHICAL ABSTRACT

KEYWORDS:

• Black gold nanoparticles
• graphitic carbon nitride
• broadband light absorption
• photocatalytic degradation
• methylene blue

Acknowledgment

Payame Noor University are gratefully acknowledged for their support of this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.