Prominence of Cu in a plasmonic Cu-Ag alloy decorated SiO2@S-doped C3N4 core-shell nanostructured photocatalyst towards enhanced visible light activity

Enhanced plasmonic photocatalytic performance of C3N4/Cu by the introduction of a reduced graphene oxide interlayer

Cu nanoparticles (NPs) are low-cost surface plasmonic resonance (SPR) metal nanostructures, and their SPR properties can be used to enhance the photocatalytic hydrogen evolution performance of carbon nitride (C₃N₄). But their actual performance is usually limited, and one key factor is their poor interfacial quality. In this work, a highly conductive reduced graphene oxide (RGO) interlayer is introduced between protonated C₃N₄ (PCN) nanosheets and Cu NPs, which can act as an efficient sink for photogenerated electrons from C₃N₄ and hot electrons from Cu NPs, and simultaneously serve as reaction sites for the hydrogen evolution reaction, and accelerate the charge transport by the formed C-O-C and C-O-Cu bonds. The optimal hydrogen evolution rate of the optimized PCN/RGO/Cu is 1.30 mmol g^-1 h^-1, which is 6.76, 2.47 and 2.41 times that of PCN, PCN/RGO and PCN/Cu, respectively, and it can further reach up to 13.22 mmol g^-1 h^-1 by loading moderate Pt NPs. Meanwhile, the introduced RGO can effectively anchor Cu NPs to enhance the stability of the photocatalyst. In addition, due to the broad SPR response of Cu NPs, a near-infrared photocatalytic performance is realized for PCN/RGO/Cu with an apparent quantum efficiency of 0.46% at 765 nm.

Synthesis of neodymium ferrite incorporated graphitic carbonitride (NdFe2O4@g-C3N4) and its application in the photodegradation of ciprofloxacin and ampicillin in a water system

Purification of antibiotic-contaminated drinking water sources is faced with limitations. Therefore, this study incorporated neodymium ferrite (NdFe2O4) in graphitic carbonitride (g-C3N4) to form NdFe2O4@g-C3N4 as a photocatalyst for removing ciprofloxacin (CIP) and ampicillin (AMP) from aqueous systems. X-ray diffraction (XRD) revealed a crystallite size of 25.15 nm for NdFe2O4 and 28.49 nm for NdFe2O4@g-C3N4. The bandgap is 2.10 and 1.98 eV for NdFe2O4 and NdFe2O4@g-C3N4, respectively. The transmission electron micrograph (TEM) images of NdFe2O4 and NdFe2O4@g-C3N4 gave an average particle size of 14.10 nm and 18.23 nm, respectively. Scanning electron micrograph (SEM) images showed heterogeneous surfaces with irregular-sized particles suggesting agglomeration at the surfaces. NdFe2O4@g-C3N4 (100.00 ± 0.00% for CIP and 96.80 ± 0.80% for AMP) exhibited better photodegradation efficiency towards CIP and AMP than NdFe2O4 (78.45 ± 0.80% for CIP and 68.25 ± 0.60% for AMP) in a process described by pseudo-first-order kinetics. NdFe2O4@g-C3N4 showed a stable regeneration capacity towards degradation of CIP and AMP with a capacity that is above 95% even at the 15th cycle of treatment. The use of NdFe2O4@g-C3N4 in this study revealed its potential as a promising photocatalyst for removing CIP and AMP in water systems.

Engineering Heterostructures of Layered Double Hydroxides and Metal Nanoparticles for Plasmon-Enhanced Catalysis

Artificially designed heterostructures formed by close conjunctions of plasmonic metal nanoparticles (PNPs) and non-plasmonic (2D) lamellar nanostructures are receiving extensive interest. The synergistic interactions of the nanounits induce the manifestation of localized surface plasmon resonance (LSPR) in plasmonic metals in the specific environment of the 2D-light absorbing matrix, impacting their potential in plasmon enhanced catalysis. Specifically, layered double hydroxides (LDH) with the advantages of their unique 2D-layered structure, tuned optical absorption, ease of preparation, composition diversity, and high surface area, have emerged as very promising candidates for obtaining versatile and robust catalysts. In this review, we cover the available PNPs/LDH heterostructures, from the most used noble-metals plasmonic of Au and Ag to the novel non-noble-metals plasmonic of Cu and Ni, mainly focusing on their synthesis strategies toward establishing a synergistic response in the coupled nanounits and relevant applications in plasmonic catalysis. First, the structure–properties relationship in LDH, establishing the desirable features of the 2D-layered matrix facilitating photocatalysis, is shortly described. Then, we address the recent research interests toward fabrication strategies for PNPs/support heterostructures as plasmonic catalysts. Next, we highlight the synthesis strategies for available PNPs/LDH heterostructures, how these are entangled with characteristics that enable the manifestation of the plasmon-induced charge separation effect (PICS), co-catalytic effect, or nanoantenna effect in plasmonic catalysis with applications in energy related and environmental photocatalysis. Finally, some perspectives on the challenges and future directions of PNPs/LDHs heterostructures to improve their performance as plasmonic catalysts are discussed.