Construction of a 0D/1D composite based on Au nanoparticles/CuBi₂O₄ microrods for efficient visible-light-driven photocatalytic activity

• Weilong Shi,
• Mingyang Li,
• Hongji Ren,
• Feng Guo,
• Xiliu Huang,
• Yu Shi and
• Yubin Tang

Beilstein J. Nanotechnol. 2019, 10, 1360–1367, doi:10.3762/bjnano.10.134

• photocatalyst consisting of Au nanoparticles (NPs) and CuBi2O4 microrods (Au/CBO) was designed and prepared by a simple thermal reduction–precipitation approach. It shows excellent photocatalytic performance in the degradation of tetracycline (TC). The maximum photocatalytic degradation rate constant for Au/CBO

• composites with 2.5 wt % Au NPs was 4.76 times as high as that of bare CBO microrods. Additionally, the 0D/1D Au/CBO composite also exhibited ideal stability. The significant improvement of the photocatalytic performance could be attributed to the improved light harvesting and increased specific surface area

• degradation of organic contaminants in water [13][14]. However, bare CuBi2O4 shows poor photocatalytic performance under visible-light irradiation because of the rapid recombination rate of photo-induced charge carriers and the low chemical affinity to substrate ions. This results in only a small portion of

A highly efficient porous rod-like Ce-doped ZnO photocatalyst for the degradation of dye contaminants in water

• Binjing Hu,
• Qiang Sun,
• Chengyi Zuo,
• Yunxin Pei,
• Siwei Yang,
• Hui Zheng and
• Fangming Liu

Beilstein J. Nanotechnol. 2019, 10, 1157–1165, doi:10.3762/bjnano.10.115

• –hole pairs are easy to recombine. The photocatalytic performance can be greatly affected by the particle size, morphology and concentration [8][9]. As such, it is possible to modify these ZnO properties to enhance its photocatalytic efficiency. Doping ZnO with rare-earth ions is an attractive strategy

• %, and 4%, respectively. The experimental results demonstrated that all CZO samples show significantly higher photocatalytic activity than ZnO. CZO-4 has the highest photocatalytic performance. It can be found that the degradation rate of RhB first increases and then decreases with the increase of Ce

• exhibits a superior catalytic performance to pristine ZnO. The change of morphology also contributes to the improvement of the photocatalytic performance of CZO, which will be further discussed in a later section. However, a further increase in the cerium concentration acts to lower the photocatalytic

Synthesis of novel C-doped g-C₃N₄ nanosheets coupled with CdIn₂S₄ for enhanced photocatalytic hydrogen evolution

• Jingshuai Chen,
• Chang-Jie Mao,
• Helin Niu and
• Ji-Ming Song

Beilstein J. Nanotechnol. 2019, 10, 912–921, doi:10.3762/bjnano.10.92

• devoted to improving the transport and separation of electron–hole pairs [10][11][12][13][14][15][16]. Among them, C atom doping for N atoms in g-C3N4 is highly promising due to its π-rich nature, which can evidently improve the photocatalytic performance of g-C3N4 [17][18][19][20][21]. For instance

• photocatalytic performance of CdIn2S4 alone is barely satisfactory, mainly due to the low separation and migration efficiency of photogenerated charge carriers. The construction of a heterojunction by combination with semiconductor materials is expected to be a strategy to improve the separation of

• charges apparently, leading to the enhancement of photocatalytic activity of the hybrid photocatalyst. Photocatalytic performance Time-dependent visible-light-induced photocatalytic H2 formation over different samples has been measured in the presence of methanol (sacrificial electron donor) without the

Deposition of metal particles onto semiconductor nanorods using an ionic liquid

• Michael D. Ballentine,
• Elizabeth G. Embry,
• Marco A. Garcia and
• Lawrence J. Hill

Beilstein J. Nanotechnol. 2019, 10, 718–724, doi:10.3762/bjnano.10.71

• similar morphologies as determined by analysis of TEM images. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis of the elemental ratios in the samples confirmed the similarity of these materials, and we compared photocatalytic performance of these two samples for degradation of

Impact of the anodization time on the photocatalytic activity of TiO₂ nanotubes

• Jesús A. Díaz-Real,
• Geyla C. Dubed-Bandomo,
• Juan Galindo-de-la-Rosa,
• Luis G. Arriaga,
• Janet Ledesma-García and
• Nicolas Alonso-Vante

Beilstein J. Nanotechnol. 2018, 9, 2628–2643, doi:10.3762/bjnano.9.244

• along the [004] direction [44], accompanied by a higher photocatalytic performance in the degradation of an organic pollutant [45]. Lee et al. also reported an enhanced photoelectrochemical behavior in photovoltaic devices ascribed to the preferred crystalline orientation due to faster electron

Hierarchical heterostructures of Bi₂MoO₆ microflowers decorated with Ag₂CO₃ nanoparticles for efficient visible-light-driven photocatalytic removal of toxic pollutants

• Shijie Li,
• Wei Jiang,
• Shiwei Hu,
• Yu Liu,
• Yanping Liu,
• Kaibing Xu and
• Jianshe Liu

Beilstein J. Nanotechnol. 2018, 9, 2297–2305, doi:10.3762/bjnano.9.214

• regarded as a promising visible-light-driven (VLD) photocatalyst because of its good activity, chemical stability and nontoxicity [15][16][17]. However, the low carrier-separation rate and narrow photo-response range of Bi2MoO6 substantially lower its photocatalytic performance [18][19]. To overcome this

• /Ag2CO3/Bi2MoO6 [32] and Ag2MoO4/Bi2MoO6 [22]. This result shows that the charge separation efficiency is enhanced in ACO/BMO-30. Photocatalytic performance The efficiency of Ag2CO3/Bi2MoO6 heterostructures in the photocatalytic degradation of industrial dyes (RhB, MO and MB), and the antibiotic TC of the

• % Bi2MoO6 exhibited a much lower activity than ACO/BMO-30, verifying that the close contact between the components also has a significant influence on the photocatalytic performance of the heterostructures. The pseudo-first-order kinetic plots and rate constants of RhB degradation for various catalysts are

Controllable one-pot synthesis of uniform colloidal TiO₂ particles in a mixed solvent solution for photocatalysis

• Jong Tae Moon,
• Seung Ki Lee and
• Ji Bong Joo

Beilstein J. Nanotechnol. 2018, 9, 1715–1727, doi:10.3762/bjnano.9.163

• indicated that our TiO2 particles photo-chemically degraded the RhB molecule completely under UV–vis light irradiation conditions. The photocatalytic performance of the TiO2 sample towards RhB degradation, determined by monitoring the peak intensity change at 553 nm vs time, was summarized in Figure 6b

• , 12, 20 and 0.7 m2/g, respectively. Supporting Information File 1, Figure S7 compares the photocatalytic performance of TiO2 samples prepared using different concentrations of HPC followed by calcination at a fixed temperature of 500 °C. The samples TiO2(HPC-1666.67)-500 and TiO2(HPC-416.67)-500

• crystalline phase transformed to its rutile counterpart, the surface area correspondingly decreased. This study determined the optimum crystallinity and surface area that yields the highest photocatalytic performance towards RhB degradation under UV–vis irradiation. Our systematic investigation may provide a

Sheet-on-belt branched TiO₂(B)/rGO powders with enhanced photocatalytic activity

• Huan Xing,
• Wei Wen and
• Jin-Ming Wu

Beilstein J. Nanotechnol. 2018, 9, 1550–1557, doi:10.3762/bjnano.9.146

• all three photocatalysts. The TGN-branch 4 h sample demonstrated enhanced photocatalytic performance as compared to TiO2 nanobelts and the TGN sample. Figure S3 in Supporting Information File 1 shows the photodegradation curves in the presence of TGN and TGN-branches with different deposition times

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

• Rashmi Acharya,
• Brundabana Naik and
• Kulamani Parida

Beilstein J. Nanotechnol. 2018, 9, 1448–1470, doi:10.3762/bjnano.9.137

• electrons from TiO2 are efficiently transported to graphene, leading to enhanced photocatalytic activity (Figure 7). Liu et al. reported that TiO2–RGO composites exhibited enhanced photocatalytic performance for the reduction of Cr(VI) by UV light illumination as compared to pure TiO2 and commercial P25

• increases with increasing RGO content and reaches a maximum value of 91% for a sample containing 0.8 wt % of RGO. However, upon further increase of the RGO content, the photocatalytic performance deteriorated [125]. This may be due to formation of recombination centers by excess RGO, which facilitates

• [150]. Hence, ZnO is considered as a suitable semiconductor to be coupled with TiO2 [151][152][153]. Joubani and coworkers reported that a ZnO/TiO2 composite photocatalysts exhibited superior photocatalytic performance by reducing a maximum of 99.99% of Cr(VI) as compared to TiO2 and ZnO, which reduced

Ag₂WO₄ nanorods decorated with AgI nanoparticles: Novel and efficient visible-light-driven photocatalysts for the degradation of water pollutants

• Shijie Li,
• Shiwei Hu,
• Wei Jiang,
• Yanping Liu,
• Yu Liu,
• Yingtang Zhou,
• Liuye Mo and
• Jianshe Liu

Beilstein J. Nanotechnol. 2018, 9, 1308–1316, doi:10.3762/bjnano.9.123

• photocatalytic performance. Keywords: AgI/Ag2WO4; nanocomposites; photocatalysis; visible light; Introduction The development of high-performance novel photocatalysts for the degradation of pollutants has received great interest due to the worsening of environmental pollution [1][2][3][4][5][6][7][8][9][10][11

• photocatalytic performance for dye degradation under light irradiation [30][31][36][37]. Unfortunately, due to its wide bandgap of about 3.1 eV, Ag2WO4 has limited photocatalytic activity under sunlight, which severely limits its application and illustrates the urgency for optimization of Ag2WO4 to overcome

• , to enhance the photocatalytic performance of Ag2WO4, AgI (possessing matched energy band levels) was chosen as a suitable component to combine with Ag2WO4, AgI/Ag2WO4 heterojunctions at different mole ratios. These heterojunctions were prepared via an in situ ion-exchange approach, utilizing Ag2WO4

Noble metal-modified titania with visible-light activity for the decomposition of microorganisms

• Maya Endo,
• Zhishun Wei,
• Kunlei Wang,
• Baris Karabiyik,
• Kenta Yoshiiri,
• Paulina Rokicka,
• Bunsho Ohtani,
• Agata Markowska-Szczupak and
• Ewa Kowalska

Beilstein J. Nanotechnol. 2018, 9, 829–841, doi:10.3762/bjnano.9.77

• wide band gap of titania of 3.0–3.2 eV and the recombination of charge carriers). There are various ways to improve photocatalytic performance of titania photocatalysts: (1) to inhibit the recombination of charge carriers, and (2) to extend its working abilities to the visible-light region, for example

Facile synthesis of a ZnO–BiOI p–n nano-heterojunction with excellent visible-light photocatalytic activity

• Mengyuan Zhang,
• Jiaqian Qin,
• Pengfei Yu,
• Bing Zhang,
• Mingzhen Ma,
• Xinyu Zhang and
• Riping Liu

Beilstein J. Nanotechnol. 2018, 9, 789–800, doi:10.3762/bjnano.9.72

• Bi/Zn molar ratio of 1:3 is the most optimal sample for photocatalytic performance. Other very critical criteria of the photocatalyst for practical application are stability and reusability. Figure 6e presents the recycling test results of the B-4 sample. After being circularly used for five times

Surface-plasmon-enhanced ultraviolet emission of Au-decorated ZnO structures for gas sensing and photocatalytic devices

• T. Anh Thu Do,
• Truong Giang Ho,
• Thu Hoai Bui,
• Quang Ngan Pham,
• Hong Thai Giang,
• Thi Thu Do,
• Duc Van Nguyen and
• Dai Lam Tran

Beilstein J. Nanotechnol. 2018, 9, 771–779, doi:10.3762/bjnano.9.70

• target gases [14][15][16]. In another research strategy to obtain high photocatalytic performance materials, ZnO, a wide-band gap semiconductor (Eg > 3 eV), can also be used as a suitable material for photocatalysts based on the particular plasmonic characteristics of the nanostructures. Herein, it was

• of ZnO was assumed to play an important role in improving their photocatalytic performance. In detail, high-energy electrons in Au NPs were injected into the conduction band of the ZnO matrix upon illumination. These electrons then drifted to the conduction band of ZnO, producing active oxygen

• cycles of photocatalytic testing, no significant difference in the photocatalytic degradation process was found, indicating excellent reversibility and stable photocatalytic performance, as shown in Figure 5b. Cascade processes have been previously reported involving the morphology, specific surface and

Perovskite-structured CaTiO₃ coupled with g-C₃N₄ as a heterojunction photocatalyst for organic pollutant degradation

• Ashish Kumar,
• Christian Schuerings,
• Suneel Kumar,
• Ajay Kumar and
• Venkata Krishnan

Beilstein J. Nanotechnol. 2018, 9, 671–685, doi:10.3762/bjnano.9.62

• a colorless, non-photosensitizing pollutant, bisphenol A (BPA). The superior photocatalytic performance of the CTCN heterojunction could be attributed to the appropriate band positions, close interfacial contact between the constituents and extended light absorption (both UV and visible region), all

• is desirable. The physical and chemical properties of a photocatalyst are related to its photocatalytic performance as three crucial factors of photocatalysis (i.e., photon absorption, charge carrier transfer and catalytic surface reactions) are dependent on them [8][9]. Two-dimensional (2D) layered

• organic semiconductor with tri-s-triazine units, has drawn huge attention from researchers due to its excellent photocatalytic performance and unique properties such as appropriate band structure, visible light absorption and high chemical and thermal stability [2][4]. In addition, g-C3N4 consists of

Mechanistic insights into plasmonic photocatalysts in utilizing visible light

• Kah Hon Leong,
• Azrina Abd Aziz,
• Lan Ching Sim,
• Pichiah Saravanan,
• Min Jang and
• Detlef Bahnemann

Beilstein J. Nanotechnol. 2018, 9, 628–648, doi:10.3762/bjnano.9.59

• . This formation is a result of notable contact between noble metal nanoparticles with a semiconductor. Plasmonic effects have been verified to increase the photocatalytic performance due to the intrinsic influences on the semiconductor photocatalyst. Plasmonic effects work to improve harvesting of

• visible and UV range [93][94][95][96]. Additionally, other noble metals such as Pt and Pd also exhibited a similar photocatalytic performance [97][98]. Ag, Au, Pt and Pd nanoparticles Ag and Au are the most preferred noble metals for interaction with various types of semiconductors due to the strong LSPR

• mechanism. Reprinted with permission from [35], copyright 2014 Royal Society of Chemistry. Synthesis of Pd/TiO2 photocatalyst via sunlight-assisted photodeposition [50]. Schematic of Au/AgBr-Ag heterostructure mechanism for improved photocatalytic performance. (a) Semiconductor-excited (AgBr) electron

Influence of the preparation method on the photocatalytic activity of Nd-modified TiO₂

• Patrycja Parnicka,
• Paweł Mazierski,
• Tomasz Grzyb,
• Wojciech Lisowski,
• Ewa Kowalska,
• Bunsho Ohtani,
• Adriana Zaleska-Medynska and
• Joanna Nadolna

Beilstein J. Nanotechnol. 2018, 9, 447–459, doi:10.3762/bjnano.9.43

• by the HT method exhibited the lowest photoluminescence intensity, which suggests that the prepared material significantly inhibited the recombination of photogenerated charge carriers, which can improve the photocatalytic performance. A possible reason is the occurrence of numerous Ti–O–Nd bonds

Sugarcane juice derived carbon dot–graphitic carbon nitride composites for bisphenol A degradation under sunlight irradiation

• Lan Ching Sim,
• Jing Lin Wong,
• Chen Hong Hak,
• Jun Yan Tai,
• Kah Hon Leong and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2018, 9, 353–363, doi:10.3762/bjnano.9.35

• [26][27], and degradation of pollutants [28][29][30]. However, the photocatalytic performance of bulk g-C3N4 remains unsatisfactory because of the fast recombination rate of electron pairs and narrower light absorption range over the entire solar spectrum. Turning g-C3N4 into a mesoporous nanorod

• amount of Ag (3.0 wt %) and CDs (1.0 wt %) resulted in a 10-fold higher degradation rate of naproxen [40]. Much of the work on g-C3N4 has been reported for environmental and energy remediation [41][42]. The above-mentioned research works suggested that the enhancement of the photocatalytic performance

• absorption spectra after titanium dioxide (TiO2) loading [28] and acid treatment [29], the incorporation of CDs into g-C3N4 consistently red-shifted the absorption spectra towards the visible and NIR region. However, the photocatalytic performance of the composites is possibly limited under NIR light

Facile synthesis of silver/silver thiocyanate (Ag@AgSCN) plasmonic nanostructures with enhanced photocatalytic performance

• Xinfu Zhao,
• Dairong Chen,
• Abdul Qayum,
• Bo Chen and
• Xiuling Jiao

Beilstein J. Nanotechnol. 2017, 8, 2781–2789, doi:10.3762/bjnano.8.277

• , followed by a UV-light-induced reduction, in which the ratio of Ag to AgSCN can be controlled by simply adjusting the photo-induced reduction time. The degradation of a representative contaminate, oxytetracycline, which often exists in contaminated water, was used to test the photocatalytic performance of

• ). Photocatalytic performance test The photocatalytic performance of the Ag@AgSCN nanostructures was evaluated by degradation of oxytetracycline (20 mg/L aqueous solution) at ambient temperature and pressure. To establish the adsorption–desorption equilibrium, the dispersion was stirred for 30 min under dark prior

Hydrothermal synthesis of ZnO quantum dot/KNb₃O₈ nanosheet photocatalysts for reducing carbon dioxide to methanol

• Xiao Shao,
• Weiyue Xin and
• Xiaohong Yin

Beilstein J. Nanotechnol. 2017, 8, 2264–2270, doi:10.3762/bjnano.8.226

• ] synthesized rod-like KNb3O8 by using KCl, K2CO3, and Nb2O5 by calcination at 800 °C for 3 h. Zhan et al. [20] prepared the single-crystalline KNb3O8 nanobelts via a molten salt method and investigated its photocatalytic performance in degradation of methyl orange under UV irradiation. To the best of our

• -synthesized samples. As is known, the higher the emission peak intensity, the more efficient the recombination of photogenerated carriers, which may limit the photocatalytic performance [26]. In Figure 10, KNb3O8 nanosheets excited high emission peaks. However, after 2 wt % ZnO quantum dots were loaded onto

• carriers is prolonged and the photocatalytic performance could be enhanced. The photocatalytic reaction mechanism is as follows. Photoexcitation of catalyst: The conduction band: The valence band [31]: Conclusion In this experiment, ZnO quantum dots were loaded onto KNb3O8 nanosheets via a two-step

Two-dimensional carbon-based nanocomposites for photocatalytic energy generation and environmental remediation applications

• Suneel Kumar,
• Ashish Kumar,
• Ashish Bahuguna,
• Vipul Sharma and
• Venkata Krishnan

Beilstein J. Nanotechnol. 2017, 8, 1571–1600, doi:10.3762/bjnano.8.159

• , thermal, optical and mechanical properties, graphene helps to enhance the photocatalytic performance by acting as excellent electron acceptor and transporter in nanocomposites. Moreover, enhanced pollutant adsorption on the surface of graphene is an additional advantage, which accelerates the

• morphology of catalytic material. Therefore the fabrication of g-C3N4 with different microstructures is expected to show different surface properties and ability to enhance the photocatalytic performance. As per one of the reports by Zhu et al., g-C3N4 synthesized by using melamine, thiourea, or urea as

• -C3N4–Ag3VO4, g-C3N4–ZnWO4, g-C3N4–SrTiO3, g-C3N4–BiWO4, and g-C3N4–Bi2WO6. Such kinds of nanocomposites have been widely explored with remarkably enhanced photocatalytic performance as compared to their respective bare counterparts. Recently, Woo et al. [84] reported their investigation on a sulfur

ZnO nanoparticles sensitized by CuInZn_xS_2+x quantum dots as highly efficient solar light driven photocatalysts

• Florian Donat,
• Serge Corbel,
• Halima Alem,
• Steve Pontvianne,
• Lavinia Balan,
• Ghouti Medjahdi and
• Raphaël Schneider

Beilstein J. Nanotechnol. 2017, 8, 1080–1093, doi:10.3762/bjnano.8.110

• heterojunction between ZnO nanoparticles and ZCIS QDs. Photocatalytic performance test A 100 mL Pyrex glass flask was used as a batch reactor. All experiments were performed at ambient temperature (20 ± 2 °C). In a typical photocatalytic experiment, 30 mg of the ZnO/ZCIS catalyst were added to 50 mL of an

• visible region, centered at ≈675 nm and dependent on the loading in ZCIS QDs is observed (Supporting Information File 1, Figure S4). An increased photo-response of ZnO/ZCIS composites in the visible region compared to ZnO can thus be expected. With the aim of investigating the photocatalytic performance

High photocatalytic activity of Fe₂O₃/TiO₂ nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid

• Shu Chin Lee,
• Hendrik O. Lintang and
• Leny Yuliati

Beilstein J. Nanotechnol. 2017, 8, 915–926, doi:10.3762/bjnano.8.93

• , titanium dioxide (TiO2) has been the foremost established material for degradation of organic pollutants [1][2]. In addition to its nontoxicity, abundance and relatively low cost, TiO2 also shows excellent photocatalytic activity in many degradation reactions. Unfortunately, the photocatalytic performance

• of the best modifiers, the use of a co-catalyst has been recognized to improve the photocatalytic performance of semiconductor photocatalysts as it promotes charge separation and suppresses photocorrosion of the semiconductor photocatalyst [3][4]. One of the potential co-catalyst modifiers is iron

• of the TiO2. With increased loading of Fe2O3, the photocatalytic performance of TiO2 in fact decreased. As another control experiment, α-Fe2O3 synthesized at 500 °C for 4 h was also tested for the removal of 2,4-D. The removal of 2,4-D using α-Fe2O3 was only 2% after 1 h of UV illumination, which

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

• higher than the efficiency of TiO2 nanospheres (65%) [97]. The graphene-based nanoarchitecture of TiO2 nanospindles [98], TiO2 nanorods [92] and TiO2 mesoporous [99] shows improved photocatalytic performance via structural optimisation of the architecture. Although most of the applications of graphene

Photocatalysis applications of some hybrid polymeric composites incorporating TiO₂ nanoparticles and their combinations with SiO₂/Fe₂O₃

• Andreea Laura Chibac,
• Tinca Buruiana,
• Violeta Melinte and
• Emil C. Buruiana

Beilstein J. Nanotechnol. 2017, 8, 272–286, doi:10.3762/bjnano.8.30

• through UV irradiation and can be conducted in very short time (seconds/minutes) at room temperature with no degradation of sensitive molecules [45][46]. The impact of the addition of different inorganic parts to the TiO2 NPs on the nanocomposite properties, including their photocatalytic performance in

• UV radiation. The combination of titania with maghemite nanoparticles induced an increase of the absorption for S3 and S4 composites above 300 nm, a convenient characteristic for photocatalytic applications. Evaluation of photocatalytic activity of the hybrid composites The photocatalytic performance

• concentration as a function of irradiation time we used the Lambert–Beer law (A = ε·l·c), and the resulting plots are given in Figure 6c. It was found that the phenol degradation efficiency depends on the hybrid film employed as catalyst, and the photocatalytic performance is improved by the addition of other

Laser irradiation in water for the novel, scalable synthesis of black TiO_x photocatalyst for environmental remediation

• Massimo Zimbone,
• Giuseppe Cacciato,
• Mohamed Boutinguiza,
• Vittorio Privitera and
• Maria Grazia Grimaldi

Beilstein J. Nanotechnol. 2017, 8, 196–202, doi:10.3762/bjnano.8.21

• readily employed for water decontamination. In order to enhance the photocatalytic performance of TiO2 under visible (solar) irradiation, many efforts have been made in the last years, ranging from doping with N, C and transition metals [7][8][9], to coupling with narrow band gap semiconductor quantum

• absorption in UV–vis and IR ranges. Indeed, the presence of hydrogen (either interstitial, in TiH or in OH complexes) can effectively enhance the photocatalytic performance of the film [2][6][20][21][22][24][25]. Furthermore, H-rich zones on the surface can enhance electron scavenging, preventing