Fenton-like Catalytic Performance Research Articles

Boosting Fenton-like catalytic performance and environmental stability of nano zero-valent copper (nCu(0)) catalyst by inhibiting the formation of oxide layer: Catalytic performance and mechanistic study

Nano zero-valent copper (nCu(0)) as Fenton-like catalyst has shown great potential in the treatment of organic wastewater. However, nCu(0) is prone to be agglomerated and oxidated, causing to the reduction in catalytic ability. Herein, biochar supported highly dispersed nCu(0) (Cu/C) was synthesized by the carbonization method. And acid-modified strategy was proposed to inhibit the oxidation of nCu(0). Physicochemical properties of Cu/C catalysts modified by different acid (HCl, H2SO4 and HNO3) were analyzed by various characterizations. The results showed that only the introduction of HCl could obviously inhibit the formation of oxide layer on Cu(0), while HNO3 and H2SO4 couldn’t. Furthermore, the content of oxide layers decreased with the increase in HCl addition. Correspondingly, the catalytic performance enhanced gradually. Cu(0) was proved to be the active centers. And the presence of oxide layers was adverse to the catalytic reaction. When the adding amount of HCl reached to 1 mL, the Cu/C-HCl-1.0 catalyst showed the optimal catalytic performance. 97.1 % of p-nitrophenol (PNP) was degraded within 60 min. The reaction rate was 7.6 times that of unmodified Cu/C catalyst. Furthermore, Cu/C-HCl-1.0 catalyst possessed excellent environmental stability. After being directly exposed to air for 4 months, catalytic performance had no obvious decrease. In addition, the catalyst showed efficient degradation ability to phenols, dyes and antibiotics. And it was not sensitive to the initial pH of the organic solution (3.7 ∼ 11.2). OH was confirmed to be the main reactive species for the degradation of organic pollutants, which was formed by the decomposition of PMS by obtaining electrons from Cu(0). This work proposed a novel and efficient method to enhance the catalytic ability and environmental stability of Cu(0) by inhibiting the formation of oxide layer.

Superoxide radicals dominated hydrogen peroxide activation using BiOI for boosting Fenton-like catalytic degradation of bisphenol A

Herein, flower-like BiOI micro-spherulites were successfully prepared via a solvothermal method, and it exhibited a remarkably Fenton-like catalytic efficacy in the degradation of BPA under dark condition without additional energy input. BiOI can function as an electron-poor center, facilitating the activation of H2O2 into •O2−, while simultaneously serving as an electron-rich center to reduce dissolved O2 to •O2−. This electron-rich and electron-poor centers of BiOI synergistically enhance the •O2− generation for highly Fenton-like catalytic performance. Moreover, the removal performance of BPA demonstrated a significant pH dependency, and the presence of low concentrations of halide ions and humic acid did not exhibit noticeable inhibitory effect on the degradation of BPA. Additionally, several intermediates have been identified to propose a comprehensive degradation mechanism for BPA. This study presents a novel BiOI Fenton-like catalytic system for the purification of recalcitrant organic pollutants in wastewater.

Pyrazine-based iron metal organic frameworks (Fe-MOFs) with modulated O-Fe-N coordination for enhanced hydroxyl radical generation in Fenton-like process

Rational design of coordination environment of Fe-based metal-organic frameworks (Fe-MOFs) is still a challenge in achieving enhanced catalytic activity for Fenten-like advanced oxidation process. Here in, novel porous Fe-MOFs with modulated O-Fe-N coordination was developed by configurating amino terephthalic acid (H2ATA) and pyrazine-dicarboxylic acid (PzDC) (Fe-ATA/PzDC-7:3). PzDC ligands introduce pyridine-N sites to form O-Fe-N coordination with lower binding energy, which affect the local electronic environment of Fe-clusters in Fe-ATA, thus decreased its interfacial H2O2 activation barrier. O-Fe-N coordination also accelerate Fe(II)/Fe(III) cycling of Fe-clusters by triggering the reactive oxidant species mediated Fe(III) reduction. As such, Fe-ATA/PzDC-7:3/H2O2 system exhibited excellent degradation performance for typical antibiotic sulfamethoxazole (SMX), in which the steady-state concentration of hydroxyl radical (OH) was 1.6 times higher than that of unregulated Fe-ATA. Overall, this study highlights the role of O-Fe-N coordination and the electronic environment of Fe-clusters on regulating Fenton-like catalytic performance, and provides a platform for precise engineering of Fe-MOFs.

Fe-Co-Based Metal-Organic Frameworks as Peroxidase Mimics for Sensitive Colorimetric Detection and Efficient Degradation of Aflatoxin B1.

Building multifunctional platforms for integrating the detection and control of hazards has great significance in food safety and environment protection. Herein, bimetallic Fe-Co-based metal-organic frameworks (Fe-Co-MOFs) peroxidase mimics are prepared and applied to develop a bifunctional platform for the synergetic sensitive detection and controllable degradation of aflatoxin B1 (AFB1). On the one hand, Fe-Co-MOFs with excellent peroxidase-like activity are combined with target-induced catalyzed hairpin assembly (CHA) to construct a colorimetric aptasensor for the detection of AFB1. Specifically, the binding of aptamer with AFB1 releases the prelocked Trigger to initiate the CHA cycle between hairpin H2-modified Fe-Co-MOFs and hairpin H1-tethered magnetic nanoparticles to form complexes. After magnetic separation, the colorimetric signal of the supernatant in the presence of TMB and H2O2 is inversely proportional to the target contents. Under optimal conditions, this biosensor enables the analysis of AFB1 with a limit of detection of 6.44 pg/mL, and high selectivity and satisfactory recovery in real samples are obtained. On the other hand, Fe-Co-MOFs with remarkable Fenton-like catalytic degradation performance for organic contaminants are further used for the detoxification of AFB1 after colorimetric detection. The AFB1 is almost completely removed within 120 min. Overall, the introduction of CHA improves the sensing sensitivity; efficient postcolorimetric-detection degradation of AFB1 reduces the secondary contamination and risk to the experimental environment and operators. This strategy is expected to provide ideas for designing other multifunctional platforms to integrate the detection and degradation of various hazards.

High-density single-atomic Ni–N4 sites for efficient Fenton-like reactions

A cascade anchoring strategy was developed to construct Ni–NC single atom catalysts with high-density Ni–N4 sites, enabling an excellent Fenton-like catalytic performance.

Enhancing Fenton-like Degradation of Organic Pollutants at Neutral pH by Multivalent Cu NCs/HAp Nanocatalysts.

Heterogeneous Fenton-like catalysis is a widely used method for the degradation of organic pollutants. However, it still has some limitations such as low activity in the neutral condition, low conversion rates of metals with different valence states, and potential secondary metal pollution. In this study, a Fenton-like nanocatalyst was first created by generating ultrasmall copper nanoclusters (Cu NCs) on the surface of hydroxyapatite (HAp) through a process of doping followed by modification. This resulted in the formation of a composite nanocatalyst known as Cu NCs/HAp. With the help of hydrogen peroxide (H2O2), Cu NCs/HAp exhibits an outstanding Fenton-like catalytic performance by efficiently degrading organic dyes such as methylene blue under mild neutral conditions. The removal rate can reach over 83% within just 30 min, demonstrating ideal catalytic universality and stability. The improved Fenton-like catalytic performance of Cu NCs/HAp can be ascribed to the synergistic effect of the multivalent Cu species through two simultaneous reaction pathways. During route I, the embedded Cu NCs with a core-shell Cu0/Cu+ structure can undergo sequential oxidation to form Cu2+, which continuously activates H2O2 to generate hydroxyl radicals (•OH) and singlet oxygen (1O2). In route II, Cu2+ produced from route I and initially adsorbed on the surface of HAp can be reduced by H2O2, thus regenerating Cu+ species for route I and achieving a closed-loop reaction. This work has confirmed that Cu NCs loaded on HAp may be an alternative Fenton-like catalyst for degradation of organic pollutants and environmental remediation, opening up new avenues for potential applications of other Cu NCs in future water pollution control.

Hierarchical MnO2-ZnO functionalized SiO2 nanofibrous membranes with enhanced Fenton-like catalytic performance for dye removal

In this work, flexible and hierarchical structured MnO2-ZnO/SiO2 nanofibrous membranes (NFMs) as easily recyclable Fenton-like catalysts have been developed utilizing the combination of electrospinning and a hydrothermal growth method. By capitalizing the advantages of the high specific surface area and synergism effects of bimetallic oxides, the optimal membranes exhibited prominent catalytic activity in the degradation of malachite green oxalate (MGO). Specifically, within a mere 15 min at an initial pH, 98.1% of MGO was degraded, demonstrating a remarkable degradation rate of 0.2744 min−1. Free radical scavenging experiments and Electron Paramagnetic Resonance studies conclusively identified superoxide radical species (O2•–) as the main reactive species for the degradation of MGO. Furthermore, the resultant flexible membranes displayed excellent stability and could be effortlessly recycled after catalytic process, surpassing the performance of conventional powdery Fenton-like catalysts. Notably, the resultant membranes could be used for dynamic catalyst for MGO removal and could efficiently treat 418 mL MGO with a flux of 5650.5 L m−2 h−1. The successful fabrication of these MnO2-ZnO/SiO2 membranes paves the way for the development of more efficient and applicable Fenton-like catalytic materials for water treatments and offers more inspirations for innovative designs of fiber-based or membrane-based catalysts.

In-situ synthesis of well-dispersed Cu/Cu2O nanoparticles supported on petaloid SiO2 for efficient degradation of high concentration tetracycline hydrochloride

Low-valent transition metal catalysts have shown great application potential in boosting the Fenton-like catalytic performance. The dispersity and particle size are closely related to catalytic performance. However, it is still a challenge to develop a simple and effective strategy to synthesize well-dispersed low-valent transition metal catalysts with small particle size. Herein, Cu/Cu2O nanoparticles with the size of about 42 nm are successfully in-situ synthesized during the carbonization process of surfactants, and evenly dispersed on petaloid SiO2 (x-CS catalysts). The ratio of Cu/Cu2O can be easily adjusted by changing the adding amount of Cu(NO3)2. 6-CS catalyst exhibits the optimal catalytic performance for the degradation of high concentration tetracycline hydrochloride (TC, 100 mg/L). About 89.4 % of TC is degraded within 40 min of reaction. The excellent catalytic ability is mainly attributed to the plenty of exposed highly reactive metal sites, accelerating the activation of H2O2. The experimental results show that Cu species are the catalytic active centers, in which low-valent Cu(0)/Cu(Ⅰ) plays the critical role in boosting the catalytic performance. Interestingly, the leaching concentration of Cu ions in solution is reduced to some extent, which is attributed to the adsorption by functional groups on SiO2. ∙OH, 1O2 and ∙O2– are confirmed to contribute to the degradation of TC. In addition, a catalytic mechanism is proposed in the Cu/Cu2O/SiO2/H2O2 system.

Magnetic nanoreactor Fe3O4@HNTs as heterogeneous Fenton-like catalyst for acid fuchsin degradation: Efficiency, kinetics and mechanism

Compared with traditional heterogeneous Fenton catalysis, iron-based catalysts with nano-confinement effect could significantly improve the effectiveness for organic pollutants degradation, due to the shorter migration distance and longer half-life of reactive oxygen species (ROS). Here, we encapsulated the Fe3O4 nanoparticles in the lumen of halloysite nanotubes (HNTs) by means of the electrostatic interactions to fabricate the Fe3O4@HNTs nanoreactor with an outstanding Fenton-like catalytic performance. The instrumental characterizations indicated that the Fe3O4 NPs successfully loaded on the inner wall of HNTs. An active dye acid fuchsin (AF) was chosen as the target pollution to evaluate the Fenton-like catalytic performance of Fe3O4@HNTs nanoreactor. The experimental results showed that the degradation efficiency of 50 mg L−1 AF could approach 100% in 120 min reaction time under almost neutral pHs. To have an insight into the Fenton-like mechanism of Fe3O4@HNTs nanoreactor, the comparisons of AF degradation in different systems, dominant free radicals, iron leaching concentration, H2O2 decomposition efficiency, and ·OH production efficiency were investigated in details. In addition, the degradation pathways of AF were also predicted based on the density functional theory, frontier orbit theory, and high performance liquid chromatography-quadrupole-time of flight mass spectrum (HPLC-QTOF-MS) technique.

Nitrogen coordination modulation of single-atom CoN4 enables dual-active-sites catalyst featuring synergistic organics adsorption and peroxymonosulfate activation

Minimizing the migration distance of short-lived radicals to targets is highly desirable for maximizing the heterogeneous Fenton-like catalytic performance. Herein, we design and fabricate a difunctional CoN4 single-atom catalyst, CoN4(29% pyrrolic N), composed of 29% pyrrole-type Co–N4 and 71% pyridine-type Co–N4 centers via atomic-level nitrogen coordination modulation, which enables dual-active-sites featuring synergistic peroxymonosulfate (PMS) activation and organic pollutant adsorption. Theoretical prediction and experiments demonstrate that the isolated Co site in pyridine-type Co–N4 has a relatively strong interaction with PMS than that in pyrrole-type Co–N4 because that the pyridinic N is more able to alter and optimize the electron distribution of the Co 3d orbital, namely an increased d-band center closer to the Fermi level and induced low spin-state Co formation, and thus facilitate electron transfer, enhance PMS adsorption, and reduce energy barriers of PMS activation. Meanwhile, the targets, including bisphenol A and other emerging pollutants, can be effectively adsorbed onto the pyrrolic N site in pyrrole-type Co–N4 via a “hard-soft interaction” principle and “donor–acceptor complex” process. This strategy minimizes essentially the mass transport limitation of the reaction by greatly reducing the transport distance of radicals towards pollutants. That is, the CoN4(29% pyrrolic N) can effectively induce the spatial confinement to restrict the space where the Fenton-like catalytic oxidaiton occurs in the vicinity of pollutants adsorbed, achieving rapid and effcient degradation and removal of emergying pollutants from water and wastewater.

Tuning Band Gap in Fe-Doped g-C3N4 by Zn for Enhanced Fenton-Like Catalytic Performance.

Multiple oxidation states of first-row transition-metal cations were always doped in g-C3N4 to enhance the catalytic activity by the synergistic action between the cations in the Fenton-like reaction. It remains a challenge for the synergistic mechanism when the stable electronic centrifugation (3d10) of Zn2+ was used. In this work, Zn2+ was facilely introduced in Fe-doped g-C3N4 (named xFe/yZn-CN). Compared with Fe-CN, the rate constant of the tetracycline hydrochloride (TC) degradation increased from 0.0505 to 0.0662 min-1 for 4Fe/1Zn-CN. The catalytic performance was more outstanding than those of similar catalysts reported. The catalytic mechanism was proposed. With the introduction of Zn2+ in 4Fe/1Zn-CN, the atomic percent of Fe (Fe2+ and Fe3+) and the molar ratio of Fe2+ to Fe3+ at the catalyst's surface increased, where Fe2+ and Fe3+ were the active sites for adsorption and degradation. In addition, the band gap of 4Fe/1Zn-CN decreased, leading to enhanced electron transfer and conversion from Fe3+ to Fe2+. These changes resulted in the excellent catalytic performance of 4Fe/1Zn-CN. Radicals •OH, •O2-, and 1O2 formed in the reaction and took different actions under various pH values. 4Fe/1Zn-CN exhibited excellent stability after five cycles under the same conditions. These results may give a strategy for synthesizing Fenton-like catalysts.

Bisthiourea immobilized UiO-66-NH2 supported Fe2O3 nanoparticles to accelerate dual centers Fenton-like reaction

In this paper, an efficient catalyst UiO-66-BTU/Fe2O3 was synthesized by using bisthiourea modified zirconium-based metal organic framework (Zr-MOF). The UiO-66-BTU/Fe2O3 system features outstanding Fenton-like activity that is 22.84 times and 12.91 times larger than Fe2O3 and conventional UiO-66-NH2/Fe2O3 system. It also exhibits good stability, broad pH range and recycle ability. Through comprehensive mechanistic investigations, we have ascribed the excellent catalytic performance of the UiO-66-BTU/Fe2O3 system to 1O2 and HO as the reactive intermediates, cause Zr centers can make complexation with Fe to form dual centers. Meanwhile, the CS on the bisthiourea can form Fe-S-C bonds with Fe2O3, reducing the redox potential of Fe(III)/Fe(II) and influencing the decomposing of H2O2, which indirectly regulate the interaction between Fe and Zr to accelerate electron transfer during the reaction. This work exhibits the design and understanding of the iron oxides incorporated in modified MOFs with excellent Fenton-like catalytic performance to remove phenoxy acid herbicides.

Synergy between graphitized biochar and goethite driving efficient H2O2 activation: Enhanced performance and mechanism analysis

Due to the contradiction between attractive properties and undesirable Fenton-like catalytic performance of iron minerals, how to enhance their Fenton-like catalytic activity is a critical but challenging issue. Here, we took an eco-friendly approach to improve the Fenton-like catalytic capacity of goethite (α-FeOOH) by loading it on graphitized biochar (GBC), and the results indicated that the existence of GBC could successfully facilitate the oxytetracycline (OTC) removal. The degradation rate constant of α-FeOOH/GBC-10 composite was approximately 2.1 times higher than that of α-FeOOH. GBCs with different graphitization degrees were obtained by adjusting the pyrolysis temperature. Interestingly, the improvement of catalytic activity of α-FeOOH/GBC was well correlated with the graphitization degree of GBC, and the graphitized structures (sp2-C) and functional group (CO) in GBC could expedite the blocked Fe(III)/Fe(II) cycling by speeding up the electrons transfer from H2O2 to α-FeOOH and donating electrons to Fe(III). In addition, the electron spin resonance and quenching experiments demonstrated that OTC removal was attributed to the joint action of •OH, O2−, and 1O2. This study sheds light on the possible role of GBC in Fenton-like reactions based on iron minerals and thus, lays the groundwork for the rational construction of more efficient Fenton-like catalytic systems.

Performance and working mechanism of a coal fly ash-based particle electrode in the catalytic oxidation of ofloxacin in a three-dimensional electro-Fenton reactor

Coal fly ash (CFA), corn straw, and pharmaceutical wastewater are typical solid and liquid wastes. In this study, activated carbon (CSAC) was first produced by carbonising corn straw, and then a particle electrode with Fenton-like catalytic performance (Fe/CFA-CSAC) was prepared and used in a three-dimensional electro-Fenton process (Fe/CFA-CSAC EF process) to treat ofloxacin-simulated wastewater (OSW). Fe/CFA-CSAC was first characterised using SEM+EDX, XRF, BET test, and XRD, and then the critical treatment parameters of OSW were optimised (T = 30 °C, aeration rate = 3 L/min, current density = 12 mA/cm2). The catalytic oxidation process was critical in the degradation of ofloxacin, while the adsorption process played an auxiliary role. The water quality had a significant improvement, 63.6 % of COD and 51.4 % of TOC were eliminated, BOD5/COD was increased from 0.12 to 0.44, and the toxic inhibition rate was reduced by 40.8 %. Fe/CFA-CSAC EF process can effectively work in a wide pH range (2.0–9.0) and can be used at least 25 cycles. The material costs required for the preparation of Fe/CFA-CSAC was $219.9/ton and the treatment cost of OSW was $1.71/ton. Finally, the working mechanism of Fe/CFA-CSAC was proposed.

Mo-Based Heterogeneous Interface and Sulfur Vacancy Synergistic Effect Enhances the Fenton-like Catalytic Performance for Organic Pollutant Degradation.

Heterogeneous Fenton-like reactions (HFLRs) based on the in situ electrochemical generation of hydrogen peroxide (H2O2) are one of the green methods to remediate organic pollutants in wastewater. However, the design of Fenton-like catalysts with specific active sites and high pollutant degradation rate is still challenging. Here, MoS2-MoC and MoS2-Mo2N catalytic cathodes with heterojunctions were successfully prepared, and the mechanism by which hydroxyl radicals and singlet oxygen (1O2) were generated cleanly without adding chemical additives other than oxygen was clarified. The composite catalysts contained more sulfur vacancies, and the catalytic cathode achieved a high paracetamol pollutant degradation efficiency with 0.17 kWh g-1 TOC specific energy consumption. And almost 5 times higher activity was achieved compared to a pure MoS2 catalytic cathode. Experimental studies confirmed that the production of 1O2 was based on the transformation of superoxide radicals by Mo6+, and 1O2 accounted for approximately 66% of the total degradation and enhanced the nonradical behavior in the reaction. This work provides a sustainable strategy for pollutant utilization, which is valuable for solving the difficult problems of HFLRs and developing new environmental remediation technologies.

Reduced Graphene Oxide-Coated CuFeO2 with Fenton-like Catalytic Degradation Performance for Terramycin.

A novel Fenton-like catalyst made of reduced graphene oxide-coated CuFeO2 (rGO-coated CuFeO2) was synthesized by the hydrothermal reaction method to remove terramycin from aqueous solutions. The catalytic degradation performance of rGO-coated CuFeO2 for terramycin was verified with H2O2 activation. The characterization reveals that rGO-coated CuFeO2 has a micro- and mesoporous structure, with groups such as C=C/C-C, CH2-CO, and HO-C=O found on the surface. The Fenton-like catalytic degradation of terramycin by rGO-coated CuFeO2 was in line with the pseudo-second-order kinetic model, and the elevated temperature accelerated the reaction. Terramycin was catalytically degraded by rGO-coated CuFeO2 in two steps: terramycin was first adsorbed by rGO, and then Fenton-like degradation took place on its surface. This research presents new insight into the design and fabrication of Fenton-like catalysts with enhanced performance.

Photosynergetic bimetallic Fe-Cu codoped melem polymer for boosting Fenton-like catalytic performance: Insights into the enhancement mechanism

Fenton oxidation is a promising technology for wastewater treatment. However, the slow redox cycle rate of transition-metal ions limits the improvement of catalytic performance. Therefore, accelerating the redox cycle rate to boost catalytic performance is very important for practical wastewater treatment. Herein, a simple one-step thermal polycondensation method is utilized to synthesize a bimetallic Fe-Cu codoped melem polymer (CFMP). The doped Cu and Fe species are uniformly dispersed in the melem polymer to maximize the exposure of metal active sites. Compared to the monometallic doped melem polymer, the CFMP exhibits better catalytic performance for p-nitrophenol with the degradation efficiency of 91.43 % within 90 min. The excellent catalytic performance of CFMP can be attributed to the dual-synergy of bimetallic codoping and photocatalysis. In addition, the CFMP catalyst exhibits excellent catalytic performance for the degradation of multiple organic pollutants with the degradation efficiency of above 85 %. The CFMP catalyst also shows good catalytic performance over a broad pH range (2.0–11.0) with low a leaching concentration of metal ions. The catalytic performance is enhanced in natural water matrices, implying the catalyst has strong anti-interference ability. Therefore, the CFMP catalyst synthesized in this study has excellent application prospects for practical wastewater treatment.

One-Step Carbonization Synthesis of Magnetic Biochar with 3D Network Structure and Its Application in Organic Pollutant Control.

In this study, a magnetic biochar with a unique 3D network structure was synthesized by using a simple and controllable method. In brief, the microbial filamentous fungus Trichoderma reesei was used as a template, and Fe3+ was added to the culture process, which resulted in uniform recombination through the bio-assembly property of fungal hyphae. Finally, magnetic biochar (BMFH/Fe3O4) was synthesized by controlling different heating conditions in a high temperature process. The adsorption and Fenton-like catalytic performance of BMFH/Fe3O4 were investigated by using the synthetic dye malachite green (MG) and the antibiotic tetracycline hydrochloride (TH) as organic pollutant models. The results showed that the adsorption capacity of BMFH/Fe3O4 for MG and TH was 158.2 and 171.26 mg/g, respectively, which was higher than that of most biochar adsorbents, and the Fenton-like catalytic degradation effect of organic pollutants was also better than that of most catalysts. This study provides a magnetic biochar with excellent performance, but more importantly, the method used can be effective in further improving the performance of biochar for better control of organic pollutants.

Removal of water-soluble lignin model pollutants with graphene oxide loaded ironic sulfide as an efficient adsorbent and heterogeneous Fenton catalyst

Advanced oxidation processes (AOPs) have gained extensive attentions in organic decontamination in past decades. Iron-contained compound is an interesting material due to its adsorptive and catalytic performance, which has been applied widely in AOPs. Thus, graphene oxide (GO)-Fe3S4 composite was synthesized by a solvothermal process and assessed as an effective adsorptive and catalytic dual functional material in this work. The composite displayed prominent adsorptive and heterogeneous Fenton-like catalytic performance, which was affected by preparation condition and the reactive parameters in catalytic system. Under optimized reactive conditions, the GO-Fe3S4 composite yielded rapid degradation of vanillic acid, which the corresponding apparent rate constant was 1.81 × 10−1 min−1. Catalytic mechanism analysis revealed that the main oxygen species was hydroxyl radicals bounded on the surface of the composite. And the generation of •O2– was contributed to the conversion of H2O2 to •OH. The analysis of degradation intermediates of vanillic acid and p-hydroxybenzoic showed that these compounds could be mineralized to small molecules. The prominent enhanced heterogeneous Fenton-like catalytic performance of GO-Fe3S4 was due to a larger specific surface area, plenty of reductive active sites in the composite and a high mass transfer efficiency of oxidizing radicals in the reactive system.

Vital Role of Synthesis Temperature in Co–Cu Layered Hydroxides and Their Fenton-like Activity for RhB Degradation

Cu and Co have shown superior catalytic performance to other transitional elements, and layered double hydroxides (LDHs) have presented advantages over other heterogeneous Fenton catalysts. However, there have been few studies about Co–Cu LDHs as catalysts for organic degradation via the Fenton reaction. Here, we prepared a series of Co–Cu LDH catalysts by a co-precipitation method under different synthesis temperatures and set Rhodamine B (RhB) as the target compound. The structure-performance relationship and the influence of reaction parameters were explored. A study of the Fenton-like reaction was conducted over Co–Cu layered hydroxide catalysts, and the variation of synthesis temperature greatly influenced their Fenton-like catalytic performance. The Co–Cut=65°C catalyst with the strongest LDH structure showed the highest RhB removal efficiency (99.3% within 30 min). The change of synthesis temperature induced bulk-phase transformation, structural distortion, and metal–oxygen (M–O) modification. An appropriate temperature improved LDH formation with defect sites and lengthened M–O bonds. Co–Cu LDH catalysts with a higher concentration of defect sites promoted surface hydroxide formation for H2O2 adsorption. These oxygen vacancies (Ovs) promoted electron transfer and H2O2 dissociation. Thus, the Co–Cu LDH catalyst is an attractive alternative organic pollutants treatment.