Enhanced visible light photocatalytic activity of novel polymeric g-C3N4 loaded with Ag nanoparticles (original) (raw)
Related papers
Renewable and Sustainable Energy Reviews, 2018
To address the increasing challenges of clean energy and environmental issues, the development of green technology is now of prime importance. Among all, photo catalytic processes represent attractive strategy to convert directly solar energy to chemical energy. Nanostructured heterogeneous photo catalysts in this field are important due to their unique structures and tunable electronic properties. In the field of photocatalysis, g-C 3 N 4 is regarded as a potential candidate owing to its basic surface functionalities, electron-rich properties and H bonding motifs present in the network. Taking the advantages of g-C 3 N 4 as a sustainable material, it has attracted dramatically increasing interest in the area of visible-light-induced photocatalytic degradation of organic pollutants and hydrogen generation. Still as a critical factor the high rate of electron-hole recombination limits its potential applications. To optimise g-C 3 N 4 , various strategies were already established. In this contribution, we have tried to address these issues by demonstrating Ag modified plasmonic photocatalyst with tailored plasmonic-metal nanostructures. This review highlights the recent significant advances in designing Ag modified g-C 3 N 4-based nanocomposites to promote its photocatalytic activity. The rational strategies like nano-structure designing, heterojunction construction, band gap tuning of Ag modified g-C 3 N 4 based nanocomposites are summarized. Moreover, this study reveals that the improved photocatalytic activity is due to SPR effect of Ag nanoparticles which shifts the Fermi level, shows superior light harvesting capacity through sensitization and efficient electron-hole separation at the interface by creating a schottky barrior. We expect that this review will inspire the readers to extend the applications of g-C 3 N 4 in the field of photocatalysis in a green manner.
Diamond and Related Materials, 2021
In this work, we focus on synthesizing g-C 3 N 4 nanosheets with a large surface area for enhanced solar light photocatalytic performance via a simple thermal polymerization of a low-cost urea precursor in enclosed conditions. The effects of annealing duration on the phase formation, structure, and optical and photocatalytic properties of the g-C 3 N 4 nanosheets were investigated. The characterization analysis revealed that g-C 3 N 4 nanosheets with different textures, including stacked-layer, porous and ultrathin morphologies, were obtained by controlling the annealing time. The prepared g-C 3 N 4 samples offer a large specific surface area, narrow band gap and efficient separation of photogenerated electron-hole pairs with increasing annealing duration. The photocatalytic properties of the as-synthesized g-C 3 N 4 samples were examined by measuring the degradation of rhodamine B (RhB) under simulated solar irradiation. With a 100% RhB solution (10 ppm) decomposed by exposure to solar irradiation for 60 min, ultrathin g-C 3 N 4 shows considerable potential in practical applications concerning environmental remediation, especially in large-scale applications in industry.
The well-dispersed nanoparticles of Au-Ag alloys on graphitic carbon nitride (g-C 3 N 4), with varying ratios of Au, were synthesized by a facile route. The diffuse reflectance spectroscopy (DRS) verified the upsurge in the intensity of characteristic surface plasmonic resonance (SPR) absorption bands with the increasing Au contents. The photoluminescence (PL) spectroscopy estimated the role of surface dispersed Au-Ag alloy NPs on the luminescence properties of g-C 3 N 4 and the suppression the probable recombination of photo-generated excitons. The structural characterization by XRD and morphological assessment by SEM revealed the uniform dispersion of Au-Ag alloy nanoparticles on the surface of g-C 3 N 4 whereas XPS analysis endorsed the presence of Au and Ag in metallic form. The HRTEM analysis confirmed the homogeneous distribution of Au and Ag contents in the alloys. The photocatalytic activity of the Au-Ag/g-C 3 N 4 was evaluated in the exposure of natural sunlight and artificial visible light for the degradation of dye substrate and compared with that of g-C 3 N 4 , Ag/g-C 3 N 4 and Au/g-C 3 N 4. The Au-Ag alloy modified g-C 3 N 4 photocatalysts exhibited significantly higher activity for the decolorization of Rhodamine B in the visible light as compared to pure, Ag and Au loaded g-C 3 N 4 that signified the contributing role of SPR in the degradation process. The individual role of SPR in the photocatalytic process was also verified by using monochromatic (532 nm) visible laser light. The mineralization ability of the synthesized alloy catalysts was estimated by TOC removal efficiency. The kinetics of the degradation/mineralization processes under various experimental conditions was also evaluated.
Nanocomposites for Visible Light-induced Photocatalysis
The carbonaceous p-conjugated/polymeric materials have been emerging as suitable materials to synthesize nanocomposites because of their attractive nanoporous structure, controllable surface chemistry, mechanical strength and favourable interactions with the semiconducting materials. The photocatalytic performances of the traditional polymeric materials are generally poor. Their performances can be greatly improved by coupling with a host semiconducting material. This is mainly due to their unique crystal structure, stability, high conductivities, nature of formation, efficient catalytic activity, promising electrochemical and optical properties. These polymeric nanocomposites act as photo sensitizers and good visible light absorbers due to p-p* electronic transitions. In this chapter the preparation methods, microstructure analysis and photocatalytic mechanism of graphitic carbon nitride (g-C 3 N 4) and various carbonaceous p-conjugated/polymeric material composite catalysts are focused. In particular, modification of g-C 3 N 4 by various carbonaceous p-conjugated/polymeric materials result in hybridization owing to strong p-p stacking interaction, which stabilizes the hybrid nanostructure and efficiently utilize the solar spectra by extending the photocatalytic applications in NO removal, CO 2 reduction and oxygen reduction reactions, water splitting to liberate H 2 fuel and degradation of pollutants. The challenges of various p-conjugated/polymeric material modified nanocomposites of g-C 3 N 4 in the field of photocatalysis are also highlighted in this chapter to extend their applications in sustainable energy development.
Journal of Metals, Materials and Minerals, 2022
In this study, the g-C3N4/Ag-TiO2 composite photocatalysts were prepared to enhance the efficient utilization of solar energy. The g-C3N4 was synthesized by facile heat treatment of urea at 600℃ for 4 h, and 0.05 wt% to 3 wt% Ag-TiO2 were obtained through the chemical reduction method. The composite photocatalysts were prepared by mixing the g-C3N4 and Ag-TiO2 with a weight ratio of 50:50 at room temperature. The photocatalytic efficiency was carried out by using 0.05 g of photocatalysts with 10 mg•L-1 of rhodamine B 120 mL under 60 min of visible light irradiation. The experimental results indicated that a sample with 0.1 wt% Ag-TiO2 could degrade rhodamine B up to 21.21%. The g-C3N4/(0.1 wt% Ag-TiO2) and g-C3N4 showed rhodamine B degradation efficiency up to 100%, which was 10.4 times and 4.7 times of pure TiO2 and 0.1 wt% Ag-TiO2, respectively. It can be suggested that the Ag deposited on TiO2 played an important role in the absorption capability under the visible light through the surface plasmon resonance effect. In addition, heterojunction between g-C3N4 and TiO2 could reduce the recombination of electron-hole pairs.
Materials
In this study, heterostructured g-C3N4/Ag–TiO2 nanocomposites were successfully fabricated using an easily accessible hydrothermal route. Various analytical tools were employed to investigate the surface morphology, crystal structure, specific surface area, and optical properties of as-synthesized samples. XRD and TEM characterization results provided evidence of the successful fabrication of the ternary g-C3N4/Ag–TiO2 heterostructured nanocomposite. The heterostructured g-C3N4/Ag–TiO2 nanocomposite exhibited the best degradation efficiency of 98.04% against rhodamine B (RhB) within 180 min under visible LED light irradiation. The g-C3N4/Ag–TiO2 nanocomposite exhibited an apparent reaction rate constant 13.16, 4.7, and 1.33 times higher than that of TiO2, Ag–TiO2, and g-C3N4, respectively. The g-C3N4/Ag–TiO2 ternary composite demonstrated higher photocatalytic activity than pristine TiO2 and binary Ag–TiO2 photocatalysts for the degradation of RhB under visible LED light irradiation...