Water‐Stable Fluorous Metal–Organic Frameworks with Open Metal Sites and Amine Groups for Efficient Urea Electrocatalytic Oxidation

Abstract

Urea oxidation reaction (UOR) is one of the promising alternative anodic reactions to water oxidation that has attracted extensive attention in green hydrogen production. The application of specifically designed electrocatalysts capable of declining energy consumption and environmental consequences is one of the major challenges in this field. Therefore, the goal is to achieve a resistant, low‐cost, and environmentally friendly electrocatalyst. Herein, a water‐stable fluorinated Cu(II) metalorganic framework (MOF) {[Cu2(L)(H2O)2]·(5DMF)(4H2O)}n (Cu‐FMOF‐NH2; H4L = 3,5‐bis(2,4‐dicarboxylic acid)‐4‐(trifluoromethyl)aniline) is developed utilizing an angular tetracarboxylic acid ligand that incorporates both trifluoromethyl (–CF3) and amine (–NH2) groups. The tailored structure of Cu‐FMOF‐NH2 where linkers are connected by fluoride bridges and surrounded by dicopper nodes reveals a 4,24T1 topology. When employed as electrocatalyst, Cu‐FMOF‐NH2 requires only 1.31 V versus reversible hydrogen electrode (RHE) to deliver 10 mA cm−2 current density in 1.0 m KOH with 0.33 m urea electrolyte and delivered an even higher current density (50 mA cm−2) at 1.47 V versus RHE. This performance is superior to several reported catalysts including commercial RuO2 catalyst with overpotential of 1.52 V versus RHE. This investigation opens new opportunities to develop and utilize pristine MOFs as a potential electrocatalyst for various catalytic reactions.

Fluorinated Metal–Organic Frameworks with Dual-Functionalized Linkers to Enhance Photocatalytic H2 Evolution and High Water Adsorption

“…The linker, H 4 L, was initially synthesized using 2,6-dibromo-4-(trifluoromethyl)­aniline and 3,5-bis­(ethoxycarbonyl)­phenylboronic acid cross-coupling Suzuki reaction, with subsequent hydrolysis and acidification (Scheme ). , The synthesis of fluorinated MOF­(Cu)-NH 2 was then conducted according to the literature with slight modifications. , Addition of the Cu­(NO 3 ) 2 ·3H 2 O (87 mg, 0.375 mmol) and H 4 L (45 mg, 0.11 mmol) to the N , N -dimethylformamide (5 mL), distilled water (2.5 mL), and concentrated HCl (four drops) mixture was carried out. A Teflon-lined stainless steel autoclave was used to heat the mixture by autogenous pressure to 70 °C in a 48 h period followed by cooling it to room temperature at a 10 °C/h rate.…”

Production of hydrogen via water oxidation using mesoporous‐assembled SiO2@TiN nanocomposite electrocatalyst

“…However, the obstacles like as high costs and a dearth of components make widespread application [16–18] problematic. Commonly used in alkaline environments, non‐precious metal oxides like nickel (Ni) and cobalt (Co) speed up the normally slow kinetics of the oxygen evolution process (OER), or Cu based electrocatalysts, can significantly increase water splitting performance [19] . Reasons for this favoritism include the materials’ high corrosion resistance, their ability to be modulated by oxidation states like Co 3+ and Co 4+ (produced uniquely during the OER process), and the flexibility with which their morphology may be manipulated by a variety of synthetic method [20] .…”

Compositional engineering of HKUST‐1/sulfidized NiMn‐LDH on functionalized MWCNTs as remarkable bifunctional electrocatalysts for water splitting

“…48,49 These constraints can potentially be overcome by assembling advanced composites that incorporate Cu MOFs. [50][51][52] On the other hand, the presence of other transition-metal electroactive centers along with additional porous carbon materials might be required to simultaneously increase the OER and HER activity. HKUST-1 is one of the Cu-MOFs with extensive application in diverse fields, enabling its use in actual applications.…”