Two pure MOF-photocatalysts readily prepared for the degradation of methylene blue dye under visible light

Abstract

Two 3D metal-organic frameworks (MOFs) with different structures, [Cu(4,4'-bipy)Cl] (1) and [Co(4,4'-bipy)·(HCOO)] (2), were synthesized by means of a hydrothermal method using a typical ligand (4,4'-bipyridine), and characterized by elemental analyses, thermal analyses and single crystal X-ray diffraction. As MOF materials, the two complexes showed active performance for the photodegradation of methylene blue (MB) dye under visible light. MB degradation over the two MOF-based photocatalysts follows first-order kinetics. The addition of an HO electron acceptor can markedly enhance the photocatalytic MB degradation performance via a ligand-to-metal charge transfer mechanism, especially in complex 1. Complex 1 is better than complex 2 in MB photodegradation performance under the same conditions. Moreover, complex 1 showed a stable activity for MB degradation after four consecutive usages. Owing to the advantages of the visible light response, stable structure, low cost and high yield, these MOF-based photocatalysts will facilitate new efforts in environmental purification.

A Co-MOF with a (4,4)-connected binodal two-dimensional topology: synthesis, structure and photocatalytic properties

“…6). The E g value of 1.66 eV for (I) is lower than the value of 2.14 eV for related Co-MOF [Co(4,4 0 -bipy)(HCOO) 2 ] n (Zhang et al, 2018) Hosny, 2009] and 3.32-3.70 eV for four Co-MOFs (Cui et al, 2019). Photocatalysts with lower E g values usually exhibit high photocatalytic efficiency Cui et al, 2019).…”

“…7). The value of the conduction band (E c ) is À0.18 eV according to the equation (Zhang et al, 2018;Chouhan et al, 2018). The thermal stability of (I) was measured.…”

A Polypyridyl‐Based Layered Complex as Dual‐Functional Co‐catalyst for Photo‐Driven Organic Dyes Degradation and Water Splitting

“…Compared with the previously reported Cu II ‐based photocatalysts with high‐performance degradation ability towards RhB and MO, such as {[Cu II (SalImCy)](Cu I I) 2 · DMF} n [SalImCy = N , N ′‐bis[(imidazol‐4‐yl)methylene]cyclohexane‐1,2‐diamine], {[Cu 3 (μ 3 ‐OH)(μ‐Pyz) 3 (PDC)(H 2 O) 2 (CH 3 OH)] n (HPyz = 1H‐pyrazole and H 2 PDC = 3,4‐pyridinedicarboxylic acid), [(CH 3 ) 2 NH 2 ][Cu(BPT)] · DMF · 2H 2 O (H 3 BPT = biphenyl‐3,4′,5‐tricarboxylic acid), {[Cu 5 (μ 8 ‐L1) 2 (μ 3 ‐OH) 2 (H 2 O) 5 ] · 4.5DMF · 18H 2 O} n (L1 = 3‐(3′,5′‐dicarboxylphenoxy) phthalic acid), {[Cu 9 (OH) 6 Cl 2 (itp) 6 (1,4‐bdc) 3 ](NO 3 ) 2 (OH) 2 · 20H 2 O} n [itp = 1‐imidazol‐1‐yl‐3‐(1,2,4‐triazol‐4‐yl)propane and 1,4‐bdc = 1,4‐benzenedicarboxylate], [Cu 3 (L 2 )(NO 3 ) 4 (H 2 O) 4 ] n (HL 2 = pyridine‐2,6‐dicarbohydrazide based imine‐linked ligands), {[Cu 4 (OH) 2 (bix) 2 (1,2,4‐btc) 2 (H 2 O) 2 ] · 3H 2 O} n [bix = 1,4‐bis(2‐methyl‐imidazol‐1‐ylmethyl)benzene and 1,2,4‐btc = 1,2,4‐benzenetricarboxylate], and [Cu(4,4′‐bipy)Cl] n (4,4′‐bipy = 4,4′‐bipyridine), the unsaturated central Cu II atom with the coordination numbers ranged from 3 to 5 and the lower band‐gap (1.07 eV) dominated by the bulky conjugated‐backbone of the organic ligand play important roles for the enhancement of the photocatalytic activity of 1 …”

“…Constructed from diversely π‐delocalized organic ligands and inorganic central metal atoms or metal clusters, coordination polymers (CPs) with semi‐conductive properties have been becoming one of the effective photocatalysts towards the degradation of organic pollutants and water splitting under irradiation of UV and/or visible light . Up to date, lots of Zn II ‐, Cd II ‐, Co II ‐, Ni II ‐, Cu I/II ‐, and Pb II ‐based CPs with bulky π‐conjugated ligands, such as porphyrin‐like subunits, 4,4′‐bis(2‐methylbenzimidazol‐1‐ylmethyl)biphenyl, tetra(3‐imidazoylphenyl)ethylene, 3,5‐diphenyltriazolate, carboxyl derivatives of 1,10‐phenanthrolines, tetrakis(4‐pyridyl)cyclobutane, naphthalenedicarboxylate, bis‐pyridyl‐bis‐amide, and viologen derivatives have been subsequently synthesized and used to degrade Rhodamine B (RhB), methyl orange (MO), methyl blue (MB), methylene blue (MLB), congo red, as well as crystal violet. Remarkably, a microporous 3,5‐diphenyltriazolate (3,5‐Ph 2 ‐tz)‐based cationic framework with a formula of {Cu 8 (3,5‐Ph 2 ‐tz) 6 (HSO 4 ) 2 · (H 2 O) 5.5 } can completely decompose the MLB, MO, RhB, and MB within half an hour resulting from the high efficiency in generating the most active species of • OH .…”

Synthesis of MnO2 Hollow Nanospheres through Selective Etching Method as an Effective Absorbent to Remove Methyl Orange from Aqueous Solution

“…Therefore, there is an urgent need to design an efficient method for removing dye molecules from wastewater. Various technologies such as photoelectrocatalysis, mem-brane filtration, chemical oxidation, and adsorption have been proposed to solve this problem [13][14][15][16][17][18]. Nevertheless, these methods are often expensive, technically demanding, or only effective at a certain concentration.…”