Polydopamine – its Prolific Use as Catalyst and Support Material

Abstract

Polydopamine is a mussel-inspired functional material with a unique ability to form surface coatings. It is a green, environmentally benign product available very easily for a multitude of varied applications. This review attempts to collect useful information with respect to polydopamine-based catalytic studies with the use of polydopamine and modified polydopamine preparations loaded with varied catalytically active species including metal ions and metal particles. Major sections are about the use of polydopamine as catalyst material, utilization of immobilized enzymes, removal of toxic materials, results in organic synthesis, and fuel cell applications. A few examples of chiral catalysis and results of recycling studies are also treated. Data collected and analyzed indicate the importance and high potential of polydopamine-based catalysts in sustainable chemistry. of subunits attacked by an immobilized cyclohexeneamine (5) was suggested to be the transition state of CÀ C bond formation.Edouard et al. prepared catalyst 0.29 % PDA/PU by depositing PDA onto polyurethane foam (PU, 180 � 20 mg, 8 cm 3 ) and used it for the reduction of methylene blue (MB) with NaBH 4 . [48] Activities decreased gradually with repeated uses from 100 % to 35 % in run 11 but partial reactivation was achieved upon keeping the sample at 67°C for 8 h (55 % dropping below 10 % in run 13). Exposure to air at room temperature for six days proved to be somewhat more beneficial (90 % conversion in run 14 decreasing to 48 % in run 18). In a recent study they fabricated two oxidized PDA/PU samples and then loaded them with NaBH 4 . [49] One made by the usual method (dopamine/Tris, rt, 12 h, in air; sample PDA O2 PU), whereas the other was made by treating PU in a mixture of dopamine, NaOAc, and NaIO 4 (pH 5, rt, 24 h). The sample was dried (67°C) and washed thoroughly with water (PDA NaIO4 PU). Both products were dipped into an aqueous solution of NaBH 4 (0.1 M, 10 min) to afford boron contents of 2.37 and 2.11 wt%. The catalysts tested in the degradation of MB showed high activities with efficiencies of 97 % and 98 %, respectively (NaBH 4 /MB molar ratio 40, 177 mg and 209 mg catalysts, 25 min). During five reuses, the pH of the reaction medium increased because of boron loss (0.78 wt% and 0.81 wt%). The activity of PDA NaIO4 PU decreased to 89 % in run five. However, dipping the used sample into a 0.1 M NaBH 4 solution restored the original efficiency of 98 %. This, however, was only a temporary remedy, since a low efficiency of 60 % was measured in run 10. PDA was suggested by the authors to act as a redox mediator to prevent the hydrolysis/oxidation of immobilized borohydride.This formula (5) should be moved up and placed before the paragraph starting with "Edouard et al…"The Zuo group used PDA particles (avg. diameter 240 nm) to induce the reduction of MB and rhodamine B (RhB) with NaBH 4 . [50] Quinone moieties of PDA were assumed to channel electrons from NaBH 4 to the dyes. Indeed, PDA oxidized with NaIO 4 exhibited increased degradatio...

Two‐Dimensional Polydopamine Positive Electrodes for High‐Capacity Alkali Metal‐Ion Storage

“…The C1s spectra were fitted by five characteristic peaks; 284.6±0.1 eV for C=C/C−C, 285.5±0.1 eV for C−N, 286.4±0.2 eV for C−O, 287.8±0.2 eV for C=O, and 290.0±0.2 eV for COOH [21] . Compared to rGO (Figure S5b), TDPD displayed a higher content of carbonyl groups, which indicates the presence of quinone derivatives within polydopamine, such as 5,6‐indolequinone [22] . The high content of carbonyl groups in the structure is important for high‐capacity Li storage due to their reversible redox reactions with Li‐ions [12] .…”

“…[21] Compared to rGO ( Figure S5b), TDPD displayed a higher content of carbonyl groups, which indicates the presence of quinone derivatives within polydopamine, such as 5,6indolequinone. [22] The high content of carbonyl groups in the structure is important for high-capacity Li storage due to their reversible redox reactions with Li-ions. [12] The N1s spectrum of TDPD was fitted by primary amine (À NH2) at 401.7 � 0.1 eV, secondary amine (À NHÀ ) at 399.9 � 0.1 eV, and tertiary/aromatic amine (À N=) at 398.5 � 0.1 eV (Figure 2c).…”

Polydopamine-based nanoreactors: synthesis and applications in bioscience and energy materials

“…As discussed in section 3.1.3, PDA shows great potential as novel supporting materials for metal nanocrystals due to its reducing abilities to numerous types of metal ions. 100,101 Generally, PDA prevents the catalysts from aggregation and gathers reagent efficiently due to its high physical adsorption ability. In addition, the effect of PDA surface chemistry on inorganic nanocrystals has been investigated for advanced catalytic systems based on its tunable charge and conjugated structure.…”

Synthetic Application of Cyclodextrins in Combination with Metal Ions, Complexes, and Metal Particles

“…[59] Polydopamine is a catalyst material employed prolifically in varied transformations. [60] The catalyst brought about the reduction with a rate of 0.255 min À 1 affording a TOF of 1077.3 h À 1 . When used in the presence of βCD, the activation energy decreased from 33.88 kJ mol À 1 to 28.59 kJ mol À 1 .…”