Biomimetic Catalysts Based on Au@ZnO–Graphene Composites for the Generation of Hydrogen by Water Splitting

Machín, Abniel; Arango, Juan C.; Fontánez, Kenneth; Cotto, María; Duconge, José; Soto-Vázquez, Loraine; Resto, Edgar; Petrescu, Florian Ion Tiberiu; Morant, Carmen; Márquez, Francisco

doi:10.3390/biomimetics5030039

Cited by 18 publications

(32 citation statements)

References 51 publications

(97 reference statements)

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“…< 10 nm ( Figure 2 ). This is a normal characteristic when using sodium borohydride (NaBH 4 ) as a reducing agent, and it has been documented in previous works [ 25 , 26 , 27 ]. The 10%Ag@TiO 2 -P25 ( Figure 2 A) and 10%ZnO commercial ( Figure 2 C) composites consisted of supports of different shapes and sizes, of micrometers in length, and both the 10%Ag@TiO 2 NWs ( Figure 2 B) and 10%ZnO NWs ( Figure 2 D) showed significant changes in their morphology compared to the bare catalysts shown in Figure 1 .…”

Section: Resultsmentioning

confidence: 74%

Photocatalytic Activity of Silver-Based Biomimetics Composites

et al. 2021

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Different Ag@TiO2 and Ag@ZnO catalysts, with nanowire (NW) structure, were synthesized containing different amounts of silver loading (1, 3, 5, and 10 wt.%) and characterized by FE-SEM, HRTEM, BET, XRD, Raman, XPS, and UV–vis. The photocatalytic activity of the composites was studied by the production of hydrogen via water splitting under UV–vis light and the degradation of the antibiotic ciprofloxacin. The maximum hydrogen production of all the silver-based catalysts was obtained with a silver loading of 10 wt.% under irradiation at 500 nm. Moreover, 10%Ag@TiO2 NWs was the catalyst with the highest activity in the hydrogen production reaction (1119 µmol/hg), being 18 times greater than the amount obtained with the pristine TiO2 NW catalyst. The most dramatic difference in hydrogen production was obtained with 10%Ag@TiO2-P25, 635 µmol/hg, being 36 times greater than the amount reported for the unmodified TiO2-P25 (18 µmol/hg). The enhancement of the catalytic activity is attributed to a synergism between the silver nanoparticles incorporated and the high surface area of the composites. In the case of the degradation of ciprofloxacin, all the silver-based catalysts degraded more than 70% of the antibiotic in 60 min. The catalyst that exhibited the best result was 3%Ag@ZnO commercial, with 99.72% of degradation. The control experiments and stability tests showed that photocatalysis was the route of degradation and the selected silver-based catalysts were stable after seven cycles, with less than 1% loss of efficiency per cycle. These results suggest that the catalysts could be employed in additional cycles without the need to be resynthesized, thus reducing remediation costs.

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Section: Resultsmentioning

confidence: 74%

Photocatalytic Activity of Silver-Based Biomimetics Composites

et al. 2021

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“…530.2 eV, which was assigned to O 2-species in the ZnO network, and a shoulder at ca. 532.1 eV, assigned to O 2-in oxygen-deficient regions, respectively [49]. The Au4f peak (Figure 6c) was fitted to two peaks at 83.3 and 86.9 eV, attributed to Au4f7/2 and Au4f5/2 double peaks, respectively, in metallic gold (Au 0 ) [50].…”

Section: Methodsmentioning

confidence: 99%

“…The deposition of Au NPs has been described elsewhere [49]. In a typical synthesis, 1g of ZnONPs was dispersed in 100 mL of H2O and the mixture was sonicated for 30 min.…”

Section: Synthesis Of Nanomaterialsmentioning

confidence: 99%

Photocatalytic Degradation of Fluoroquinolone Antibiotics in Solution

Machín¹,

Márquez²,

Fontánez³

et al. 2022

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The photocatalytic degradation of two quinolone-type antibiotics (ciprofloxacin and levofloxacin) in aqueous solution was studied, using catalysts based on ZnO nanoparticles, which were synthesized by a thermal procedure. The efficiency of ZnO was subsequently optimized by incorporating different co-catalysts of gC3N4, reduced graphene oxide and nanoparticles of gold. The catalysts were fully characterized by electron microscopy (TEM and SEM), XPS, XRD, Raman, and BET surface area. The most efficient catalyst was 10%Au@ZnONPs-3%rGO-3%gC3N4, allowing to obtain degradations of both pollutants above 96%. This catalyst has the largest specific area, and its activity has been related to a synergistic effect, involving factors as relevant as the surface of the material and the ability to absorb radiation in the visible region, mainly produced by the incorporation of rGO and gC3N4 to the semiconductor. The use of different scavengers during the catalytic process, was used to establish the possible photodegradation mechanism of both antibiotics.

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“…The coupling of plasmonic NPs (especially Au) with a semiconductor surface is a good approach to enhance photoelectric conversion for many reasons as follows [55][56][57][58][59]. The formation of semiconductor-metal junction helps in minimizes electron-hole recombination.…”

Section: Introductionmentioning

confidence: 99%

Effect of Morphology and Plasmonic on Au/ZnO Films for Efficient Photoelectrochemical Water Splitting

et al. 2021

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To improve photoelectrochemical (PEC) water splitting, various ZnO nanostructures (nanorods (NRs), nanodiscs (NDs), NRs/NDs, and ZnO NRs decorated with gold nanoparticles) have been manufactured. The pure ZnO nanostructures have been synthesized using the successive ionic-layer adsorption and reaction (SILAR) combined with the chemical bath deposition (CBD) process at various deposition times. The structural, chemical composition, nanomorphological, and optical characteristics have been examined by various techniques. The SEM analysis shows that by varying the deposition time of CBD from 2 to 12 h, the morphology of ZnO nanostructures changed from NRs to NDs. All samples exhibit hexagonal phase wurtzite ZnO with polycrystalline nature and preferred orientation alongside (002). The crystallite size along (002) decreased from approximately 79 to 77 nm as deposition time increased from 2 to 12 h. The bandgap of ZnO NRs was tuned from 3.19 to 2.07 eV after optimizing the DC sputtering time of gold to 4 min. Via regulated time-dependent ZnO growth and Au sputtering time, the PEC performance of the nanostructures was optimized. Among the studied ZnO nanostructures, the highest photocurrent density (Jph) was obtained for the 2 h ZnO NRs. As compared with ZnO NRs, the Jph (7.7 mA/cm2) of 4 min Au/ZnO NRs is around 50 times greater. The maximum values of both IPCE and ABPE are 14.2% and 2.05% at 490 nm, which is closed to surface plasmon absorption for Au NPs. There are several essential approaches to improve PEC efficiency by including Au NPs into ZnO NRs, including increasing visible light absorption and minority carrier absorption, boosting photochemical stability, and accelerating electron transport from ZnO NRs to electrolyte carriers.

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Biomimetic Catalysts Based on Au@ZnO–Graphene Composites for the Generation of Hydrogen by Water Splitting

Cited by 18 publications

References 51 publications

Photocatalytic Activity of Silver-Based Biomimetics Composites

Photocatalytic Activity of Silver-Based Biomimetics Composites

Photocatalytic Degradation of Fluoroquinolone Antibiotics in Solution

Effect of Morphology and Plasmonic on Au/ZnO Films for Efficient Photoelectrochemical Water Splitting

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