Visible light-driven novel g-C₃N₄/NiFe-LDH composite photocatalyst with enhanced photocatalytic activity towards water oxidation and reduction reaction

Abstract

Exploiting the advantage of a layered architecture, layered graphitic carbon nitride (CN) and NiFe-layered double hydroxide (LDH) have been coupled in the present investigation to design a series of highly efficient novel CNLDH composites for visible light-induced photocatalytic H 2 and O 2 evolution. The syntheses of these composites were carried out using a facile weight impregnation method while varying the wt% of CN on LDH. The structural, optical, and morphological properties of these composites were characterized by various physicochemical techniques. The results indicate a tuned-in band gap energy within the range of pure LDH to pure CN. In addition, the remarkable quenching of the PL signal and prolonged photogenerated charge lifetime confirmed by TRPL spectra demonstrates the excellent photocatalytic activity of these composites. The activity could be ascribed to the dispersion of exfoliated CN over the brucite layer of LDH, in which strong energy transfer takes place in terms of charge carriers.The visible light-induced photocatalytic H 2 and O 2 evolution study resulted in an enhancement in the activity of the CNLDH10 composite with a H 2 evolution rate of 1488 mmol 2 h À1 and O 2 evolution rate of 886 mmol 2 h À1 . The high photocatalytic activities of these composites may be due to good dispersion of exfoliated CN over the brucite layer of edge-shared MO 6 octahedra, higher life time of charge carriers, low PL intensity, appropriate band gap energy and enhancement in photocurrent density. of electrons and holes. 5 The common layered structures of ZnCr-LDH and layered titanate enable an effective physical contact and a strong electronic coupling between them, which is effective in enhancing the photocatalytic activity of ZnCr-LDH. This motivated us to take the challenge of designing composite photocatalysts by coupling LDH with other layered semiconductor materials, like metal-free polymeric graphitic carbon nitride (g-C 3 N 4 ), which has an appropriate band gap of 2.7 eV and optical absorption in the visible region. 18 The g-C 3 N 4 material also possesses very high thermal, mechanical and chemical stability. Many studies have been focused on the applications of g-C 3 N 4 materials in photocatalytic water splitting together with degradation of organic pollutants. [19][20][21][22] However, recent studies have indicated that these materials exhibit photocatalytic activities for both H 2 and O 2 evolution under visible light irradiation in the presence of a sacricial donor and acceptor. 23 Several composite materials coupled with g-C 3 N 4 have also been reported, such as g-

Layered Double Hydroxides: Tailoring Interlamellar Nanospace for a Vast Field of Applications

“…Better absorption range and better charge transfer separation was obtained [64][65][66]. Feng et al [67] recently propose a simple synthesis of a CoFe layered double hydroxide, with high activity and stable oxygen evolution.…”

Photocatalysts with adsorption property for dye-contaminated water purification

“…79 Calcination of LDHs above 600°C is generally known to crystallise and yield AO and spinel-type oxides, AB2O4, which can resist water from LDHs structure reforming. 23,35 These derived MMO materials have been reported to display outstanding magnetic, catalytic and textual properties. [80][81][82] There are a large number of studies concerning the preparation of multi-cationic oxides or spinel-type oxides through thermal decomposition of LDHs, 23 The spinel structure MM2O4 such as ZnFe2O4, ZnAl2O4 derived from calcined LDH precursors have also been reported with good photocatalytic activity.…”

“…It is predictable that combining LDH with g-C3N4 results in inorganic/organic hybrid composites that would exhibit the following advantages: firstly, coupling two layered semiconductors to form a composite semiconductor system facilitates the separation of the photogenerated electron-hole pairs; secondly, the layered structure with considerable thermodynamic stability, including mixed valency metal ions (divalent, trivalent) and good exposure of catalytically active sites, can participate in the process due to the dispersion of g-C3N4 over the surface of LDH. 201 However, there is limited research on the composition between LDH and g-C3N4. 166,[201][202][203][204] There is even fewer research on the composition between LDH and g-C3N4 which is used in water purification.…”

“…201 However, there is limited research on the composition between LDH and g-C3N4. 166,[201][202][203][204] There is even fewer research on the composition between LDH and g-C3N4 which is used in water purification.…”

“…35 Gray and coworkers 36 fabricated Mg2Al-Cl-LDH with a fast co-precipitation process followed by controlled hydrothermal treatment and analysed in detail the influence of hydrothermal treatment temperature and duration time on the particle size. The suspension of freshly precipitated Mg2Al-Cl-LDH consisted of a bimodal particle size distribution with diameters of 320 and 2300 nm, respectively.…”