Enhancing dechlorination and inhibiting H2 evolution: Surface N-hydroxymethylation of Pd-loaded carbon nitride for photocatalytic elimination of polychlorinated aromatics

• Published in: Journal of catalysis Vol. 438; p. 115732
• Main Authors: Sun, Zhaoli, Fan, Yafei, Yao, Jianfei, Kong, Dezhi, Chu, Menghui, Zhang, Guanyun, Wang, Yifeng
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-10-2024
• Subjects: Carbon nitride; N-hydroxymethylation; PCB 77; Photocatalytic dechlorination; Polychlorinated aromatics; N-hydroxymethylation; PCB 77; Photocatalytic dechlorination; Polychlorinated aromatics; Carbon nitride
• ISSN: 0021-9517
• DOI: 10.1016/j.jcat.2024.115732

N-hydroxymethylation greatly improves the transfer of photo-generated electrons from PCN to Pd NPs, accelerates electron reduction of C-Cl bonds at Pd NPs’ surfaces, and inhibits H2 evolution, rendering Pd/FA-PCN highly active and selective in the hydrodechlorination of polychlorinated aromatics under visible-light irradiation.
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Polychlorinated aromatic compounds (PCAs) are a class of persistent organic pollutants (POPs) characterized by their sp2 C-Cl bonds and the aromatic rings. They are commonly found in flue gases from incinerators and other industrial processes, and are very harmful to human and wildlife health. Sunlight-driven photocatalytic reduction is a straightforward approach to eliminating PCAs. Although many photocatalysts have been developed, their activity remains unsatisfactory under visible-light irradiation, and selectivity is also impeded by the side reactions especially H2 evolution. Here, we report a Pd nanoparticles (NPs)-loaded, surface N-hydroxymethylated Polymeric carbon nitride (PCN) photocatalyst, which achieves rapid and complete hydrodechlorination of PCAs under visible-light irradiation in water. Mechanism studies reveal that contacting Pd NPs with N-hydroxymethylated PCN surfaces boosts the transfer of photo-generated electrons from PCN to Pd NPs and the reduction of C-Cl bonds at the Pd NPs’ surfaces. In contrast, the amino groups of pristine PCN render the catalyst less efficient in interfacial electron transfer, while more active in H2 evolution. Our findings highlight the potential of surface engineering to improve the performance of existing photocatalysts towards selective reduction of halogenated pollutants.