Potassium Molten Salt-Mediated In Situ Structural Reconstruction of a Carbon Nitride Photocatalyst

Abstract

Metal-free polymeric carbon nitride (PCN) materials are at the forefront of photocatalytic applications. Nevertheless, the overall functionality and performance of bulk PCN are limited by rapid charge recombination, high chemical inertness, and inadequate surface-active sites. To address these, here, we employed potassium molten salts (K + X − , where X − is Cl − , Br − , and I − ) as a template for the in situ generation of surface reactive sites in thermal pyrolyzed PCN. Theoretical calculations imply that addition of KX salts to PCN-forming monomers causes halogen ions to be doped into C or N sites of PCN with a relative trend of halogen ion doping being Cl < Br < I. The experimental results show that reconstructing C and N sites in PCN develops newer reactive sites that are beneficial for surface catalysis. Interestingly, the photocatalytic H 2 O 2 generation rate of KBr-modified PCN was 199.0 μmol h −1 , about three times that of bulk PCN. Owing to the simple and straightforward approach, we expect molten salt-assisted synthesis to have wide exploration in modifying PCN photocatalytic activity.

Recent progress in graphitic carbon nitride-based materials for antibacterial applications: synthesis, mechanistic insights, and utilization

“…This cost-effective and easily operable method has been highlighted [37,43] . Taking cyanuramide as an illustrative case [44] , the transformation cascade begins at 150 °C, progressing from cyanuramide to dicyandiamide and further evolving into melamine at 240 °C. As the temperature climbs to 390 °C, the initial formation of C 6 N 7 units takes place, culminating at around 520 °C with the formation of g-C 3 N 4 through additional deamination-condensation reactions.…”

Counterion chemistry of 5-halo (X: Cl, Br, I)-uracil derived carbon nitride: unlocking enhanced photocatalytic performance

“…Incorporating non-metals such as F, Cl, Br, or I through elemental doping is another effective way to influence the electronic band structure of the PCN framework by reconstructing the corresponding highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). 15 For example, Wang et al created an extended aromatic heterocycle via iodine doping, which generated impurity energy levels near the valence band (VB) edge, resulting in an enhanced optical response and hydrogen evolution activity. 16 Similarly, PCN doped with F, Cl, and Br has demonstrated a significant surge in photocatalytic hydrogen production, and photooxidation behaviour.…”

Machine-Learning-Driven High-Throughput Screening of Transition-Metal Atom Intercalated g-C3N4/MX2 (M = Mo, W; X = S, Se, Te) Heterostructures for the Hydrogen Evolution Reaction

“…In this regard, hydrogen is emerging as a promising replacement for existing energy resources, , and efforts are underway to enhance its commercial viability through the development of robust catalytic materials. The process of electrochemical water splitting, with particular focus on the hydrogen evolution reaction (HER), has demonstrated remarkable efficiency as a method for hydrogen production. , Owing to their cost-effectiveness, large surface areas, earth abundance, good stability, and adjustable catalytic behavior, two-dimensional (2D) materials like graphitic carbon nitride (g-C 3 N 4 ) , and transition-metal dichalcogenides (TMDs) , possess significant potential to enhance the HER activity. Specifically, the band gap of g-C 3 N 4 (2.70 eV) is suitable for photocatalysts, effectively covering both water reduction and oxidation, yet its photocatalytic efficiency is compromised by rapid recombination of electron–hole pairs .…”