The rational design of Au0/g-C3N4 photocatalysts with enhanced charge separation for visible-light-driven water purification

Almalki, Mshaal, Akdim, Ouardia, Hayward, James S., Edwards, Jennifer K. ORCID: https://orcid.org/0000-0003-4089-2827 and Bartley, Jonathan K. ORCID: https://orcid.org/0000-0003-4640-541X 2026. The rational design of Au0/g-C3N4 photocatalysts with enhanced charge separation for visible-light-driven water purification. Materials Today Sustainability 34 , 101348. 10.1016/j.mtsust.2026.101348

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Abstract

Gold nanoparticle doped graphitic carbon nitride (Au/g-C3N4) photocatalysts were synthesized via different preparation methods and evaluated for the visible-light-driven degradation of methyl orange at room temperature. All Au-modified samples exhibited superior photocatalytic activity compared to unmodified g-C3N4, which was attributed to the positive role of gold in enhancing charge separation. Notably, catalysts containing well-dispersed Au bimodal size distribution (<0.5 nm intercalated between the layers and 2 nm on the surface) displayed the highest efficiency, achieving complete methyl orange degradation within 180 min. The superior activity of the simple impregnation-derived sample was attributed to its small Au particle size and strong interaction with the g-C3N4 matrix, which facilitated electron trapping and reactive oxygen species generation as shown by photoluminescence, photocurrent response and electrochemical impedance spectroscopy Nyquist plots. The degradation mechanism was determined based on radical scavenger experiments and the dominant reactive species observed were superoxide radicals (O2•−), hydroxyl radicals (•OH), and photogenerated holes (h+). The solution pH was found to significantly influence the initial adsorption of methyl orange onto the catalyst surface, thereby affecting the overall degradation process. Among the tested strategies, incipient wetness and impregnation routes emerged as promising, facile approaches for the preparation of efficient photocatalysts. This work highlights how synthesis methodology critically governs the physicochemical properties and photocatalytic performance of Au/g-C3N4, offering valuable insights for the design of photocatalysts as sustainable materials for water purification.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Chemistry Research Institutes & Centres > Cardiff Catalysis Institute (CCI)
Publisher:	Elsevier BV
ISSN:	2589-2347
Date of First Compliant Deposit:	23 March 2026
Date of Acceptance:	15 March 2026
Last Modified:	23 Mar 2026 16:15
URI:	https://orca.cardiff.ac.uk/id/eprint/185971

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