Core/Shell Structure of Mesoporous Carbon Spheres and g-C3N4 for Acid Red 18 Decolorization

Abstract

Spherical photocatalyst based on ordered mesoporous carbon and graphitic carbon nitride with core/shell structure (CS/GCN) was successfully synthesized via facile electrostatic self-assembly strategy. The photocatalytic properties of the hybrid were evaluated by the decomposition of Acid Red 18 under simulated solar light irradiation in comparison to the bulk graphitic carbon nitride (GCN). The results clearly revealed that coupling of carbon nitride with mesoporous carbon allows the catalyst to form with superior photocatalytic performance. The photoactivity of CS/GCN was over nine times higher than that of pristine GCN. Introducing mesoporous carbon into GCN induced higher surface area of the heterojunction and also facilitated the contact surface between the two phases. The synergistic effect between those two components enhanced the visible light-harvesting efficiency and improved photoinduced charge carrier generation, and consequently their proper separation. The electrochemical behavior of the obtained composite was also evaluated by electrochemical impedance, transient photocurrent response and linear sweep potentiometry measurements. The results confirmed that transport and separation of charge carriers in the hybrid was enhanced in comparison to the reference bulk graphitic carbon nitride. Detailed electrochemical, photoluminescence and radical scavenger tests enabled determination of the possible mechanism of photocatalytic process. This work presents new insights to design a core/shell hybrid through the simple preparation process, which can be successfully used as an efficient photocatalyst for the treatment of wastewater containing dyes under solar light irradiation.Catalysts 2019, 9, 1007 2 of 17 increase the surface area, the porosity in the structure of GCN can be additionally induced. Mesoporous photocatalysts received considerable research interest because they contain a special pore network, which facilitates the diffusion of the reactants and products. Moreover, the large surface area offers more active sites. Therefore, for an economical utilization of GCN, the researchers should strive to find the way for enhancing its photocatalytic properties [10,11].Up to now, different strategies, including introducing foreign elements, designing nanoporous structures, texturization, supramolecular assembly and creating effective heterojunctions, have been developed to enhance the photoactivity of GCN [12]. A large number of studies have confirmed that building a heterojunction system is an effective method to improve the separation efficiency of the photogenerated electrons and holes which dramatically improves the photocatalytic performance [13].To form an efficient heterojunction, GCN has been coupled with other semiconductors such as TiO , etc. [12,[14][15][16][17][18][19][20][21]. Unfortunately, the particles (often in the agglomerated form) were usually loaded randomly on the GCN sheets in composites causing low conjunction of GCN with a semiconductor which consequently limited charge transfer and...

Influence of Hydrogenation on Morphology, Chemical Structure and Photocatalytic Efficiency of Graphitic Carbon Nitride

“…Additionally, the VB potential of 500-4 is not more positive than that of E 0 (•OH/OH − = 1.99 eV vs. NHE); thus the holes (h + ) could not oxidize OH − /H 2 O to generate hydroxyl radicals (•OH) directly in 500-4 photocatalytic process [ 25 ]. However, •OH can be produced from the reaction between •O 2 − and H 2 O 2 , accelerating the photocatalytic activity [ 26 ]. Moreover, the ability of the organic dye itself decomposition should be considered [ 26 ].…”

“…However, •OH can be produced from the reaction between •O 2 − and H 2 O 2 , accelerating the photocatalytic activity [ 26 ]. Moreover, the ability of the organic dye itself decomposition should be considered [ 26 ]. In this case, the dye molecule can provide the electron to 500-4 through the irradiation process.…”

Bifunctional Polymeric Carbon Nitride via Tuning Fabrication Conditions for Photocatalysis

“…The presented band diagrams of all materials indicate the possibility to create hydroxyl radicals because of more positive potentials of valence bands in comparison with that of OH − /•OH potential (+1.99 eV vs. NHE). Simultaneously, only PCN prepared at 600 • C (600-4) is able to form superoxide radical, since its CB is more negative than O 2 /•O 2 − potential (−0.33 eV vs. NHE) [47]. However, this photocatalyst exhibits broad band gap (3.03 eV), indicating lower abilities for solar light harvesting.…”

Carbon Monoxide Desorption and Reduction Studies of Graphitic Carbon Nitride Supported Nickel Catalysts for CO Methanation

“…Typically, bulk g‐C 3 N 4 formed from thermal condensation is unfavorable for catalytic applications, due to low surface area (10–20 m 2 g −1 ) and less pores [13] . To overcome this problem, bulk g‐C 3 N 4 can be exfoliated to nanosheets using many exfoliation techniques such a thermal, [14] chemical, [15] and mechanical [16] to obtain higher surface area as well as porous structure to offer more active sites [17] …”

“…[13] To overcome this problem, bulk g-C 3 N 4 can be exfoliated to nanosheets using many exfoliation techniques such a thermal, [14] chemical, [15] and mechanical [16] to obtain higher surface area as well as porous structure to offer more active sites. [17] Methanation (also known as Sabatier reaction) has been extensively studied in recent years due to the great interest in the production of synthetic natural gas (SNG). Carbon monoxide (CO) methanation is the hydrogenation reaction of CO to CH 4 (Eq.…”