Higher Oxidation Efficiency Research Articles

Mechanistic insights into multimetal synergistic and electronic effects in a hexanuclear iron catalyst with a [Fe3(μ3-O)(μ2-OH)]2 core for enhanced water oxidation.

Multinuclear molecular catalysts mimicking natural photosynthesis have been shown to facilitate water oxidation; however, such catalysts typically operate in organic solutions, require high overpotentials and have unclear catalytic mechanisms. Herein, a bio-inspired hexanuclear iron(III) complex I, Fe6(μ3-O)2(μ2-OH)2(bipyalk)2(OAc)8 (H2bipyalk = 2,2'-([2,2'-bipyridine]-6,6'-diyl)bis(propan-2-ol); OAc = acetate) with desirable water solubility and stability was designed and used for water oxidation. Our results showed that I has high efficiency for water oxidation via the water nucleophilic attack (WNA) pathway with an overpotential of only ca. 290 mV in a phosphate buffer of pH 2. Importantly, key high-oxidation-state metal-oxo intermediates formed during water oxidation were identified by in situ spectroelectrochemistry and oxygen atom transfer reactions. Theoretical calculations further supported the above identification. Reversible proton transfer and charge redistribution during water oxidation enhanced the electron and proton transfer ability and improved the reactivity of I. Here, we have shown the multimetal synergistic and electronic effects of catalysts in water oxidation reactions, which may contribute to the understanding and design of more advanced molecular catalysts.

A novel approach of in-cylinder NOx control by inner selective non-catalytic reduction effect for high-pressure direct-injection ammonia engine

As an efficient hydrogen carrier and carbon-free fuel, ammonia shows great promise in realizing zero-carbon propulsions. However, challenges such as poor ignition stability, low combustion efficiency, and fuel-NOx emissions are yet to overcome. In this paper, the high-pressure direct-injection ammonia/diesel dual-fuel combustion mode (HPDF) with post injection strategy is proposed as a solution. The study reveals that HPDF combustion mode enables in-cylinder reduction of NOx, which is attributed to the selective non-catalytic reduction (SNCR) reaction. The results uncover that NH2, NH, and N radicals have a significant reducing effect on NO and NO2, while N2O serves as an important byproduct of the reduction reactions. Subsequently, the generated N2O can be further reduced to N2 through the involvement of O, H, and OH radicals. Building upon these findings, an innovative ammonia post injection method for reducing NOx emissions is explored. The post injection strategy effectively reduces the NOx emissions with only a minor decrease in indicated thermal efficiency, but an over-delayed post injection could also cause significant increase in N2O and unburned NH3 emissions. A post injection proportion of 20%-30% with appropriate post injection timing is found to achieve desired emission reduction. Overall, the HPDF combustion mode is a promising solution for ammonia engine, due to the high thermal efficiency and low nitrogen oxide emissions, as well as the ability to further reduce the NOx emissions through ammonia post injection strategy.

In situ treatment of contaminated soil using persulfate activated by sulfidated zero-valent iron

Soil contamination with hazardous substances like phenol poses significant environmental and health risks. In situ soil mixing can be a promising technological solution to this challenge. A persulfate and sulfidated zero-valent iron (S-ZVIbm) system for remediating contaminated soil was developed and tested to be suited to in situ soil mixing. S-ZVIbm was synthesized using a ball mill process, and the optimal sulfur to iron molar ratio for effectively removing phenol from soil removal without pyrophoric risks was 0.12. Soil slurry experiments were performed, and the best phenol oxidation results (high stoichiometric efficiency and sustained oxidation after mixing) were achieved at a persulfate to S-ZVIbm molar ratio of 2:1 and a persulfate to phenol molar ratio of 8:1. A high organic matter content of the silty clay fraction of the soil strongly suppressed persulfate activation, so suppressed phenol removal and increased persulfate consumption. Electron spin resonance and radical scavenging tests confirmed that hydroxyl and sulfate radicals were present during the degradation of phenol. While sulfate radicals predominantly facilitated degradation in the soil, both sulfate and hydroxyl radicals were crucial in the aqueous phase in the absence of soil organic matter. In situ soil mixing simulation tests indicated that the persulfate and S-ZVIbm doses and the mixing rate and duration strongly affected the efficacy of the system, and the optimal conditions for phenol removal were determined. The results indicated that the persulfate/S-ZVIbm system could be tuned to achieve sustained persulfate activation and to remediate contaminated soil employing in situ soil mixing technique.

Enhanced performance of photocatalytic oxidation of indoor toluene over Pd/TiO2 catalyst by tuning surface defect concentrations

An effective approach for the elimination of indoor gaseous toluene through photocatalytic oxidation involves the engineering of surface defects on catalysts. In this study, the concentrations of surface oxygen defects in PdTi-xN (x = 10, 30) catalysts were controlled using the sodium borohydride solid-phase reduction method, and their performances in the photocatalytic oxidation of indoor gaseous toluene were evaluated. PdTi–10 N demonstrated high photocatalytic efficiency for toluene oxidation, achieving 84% toluene conversion and approximately 75% CO2 mineralization. Characterization results indicated that surface oxygen defects can enhance the separation of photo-generated electrons and holes, facilitating their interaction with Pd0 species to form Ti3+ species. More reactive oxygen species (·OH-and ·O2−) were generated on PdTi–10 N due to the synergistic effect of surface oxygen defect and Ti3+ species, which played a significant role as the toluene oxidation. This work provides a new insight for the design and development of high-performance Pd/TiO2 catalysts in the field of indoor VOCs treatment.

Research Progress on Catalytic Ceramic Membrane Degradation of Phenol Containing Wastewater

In recent years, ceramic membrane supported catalysts for catalytic ozonation have made certain progress in the treatment of organic wastewater. This process has the advantages of simple operation, high oxidation efficiency, high catalyst utilization, ceramic membrane resistance to pollution, and no secondary pollution. However, the large-scale promotion and use of this process still rely on the development of highly active and stable heterogeneous catalysts. Therefore, it is crucial to summarize the development status of ceramic membrane supported ozone catalysts at home and abroad in recent years. This article first summarizes the recent research on catalytic membranes; Secondly, the production method of catalytic ceramic membrane is elaborated; Finally, the research significance of catalytic ceramic membranes is discussed.

Iron porphyrin as a cytochrome P450 model for the oxidation of xanthene

Cytochrome P450 enzyme is a superfamily of heme-containing enzyme, which play an important part in the metabolism of xenobiotics and biosynthesis of natural products. Cytochrome P450 enzyme is able to catalyze a series of challenging oxidation reactions, thus, it has attracted increased attention as a promising biocatalyst for synthetic chemistry. Transition-metal complexes of porphyrins have been successfully synthesized as models for the cytochrome P450 enzyme, and used to the oxidation of organic compounds such as hydrocarbons. In the current study, an iron porphyrin, 5,10,15,20-tetra (4-methoxyphenyl) porphine ferric chloride (III) (Fe(III)TCPP-OMe) is used as the catalyst for the oxidation of xanthene with peroxide oxidants (cumyl hydroperoxide (CmOOH) and tert‑butyl hydroperoxide (t-BuOOH)). Fe(III)TCPP-OMe shows high catalytic oxidation efficiency of xanthene and high selectivity for the formation of 9-H-xanthene-9-ol. This work provides a feasible method for the oxidation of hydrocarbons.

High performance of PrMnO3 perovskite catalysts for low-temperature soot oxidation

In the field of heterogeneous catalysis for diesel vehicle exhaust, designing low-cost catalysts with high efficiency and low-temperature catalytic oxidation to reduce the ignition temperature of soot remains a significant challenge. In this study, a series of praseodymium manganese perovskites (PrMnO3) were synthesized using a solution combustion method that regulated the molar ratio of glycine to nitrate (φ). Notably, when φ = 1, the prepared catalyst (PMO-1) exhibited a multistage pore structure and large specific surface area, demonstrating excellent catalytic oxidation performance for soot (T10 = 280 °C, T50 = 377 °C, TOF=16.2 × 10-4 s−1, SCO₂ > 99 %) and NO (maximum NO conversion rate of 80 %). During soot combustion in a NO+O2 reaction atmosphere, the strong NO oxidation capacity of the catalyst provides sufficient NO2 as an oxidant for soot combustion, thereby further enhancing its oxidation performance (T50 = 360 °C). This study concludes that the excellent low-temperature catalytic oxidation performance of the PrMnO3 catalyst is attributed to the large specific surface area provided by its multistage pore structure and the extensive dispersion of active sites, which enhance the contact efficiency between soot particles and active sites. Additionally, based on multiple characterization results such as XPS, TOF calculations, and Soot-TPR, the PMO-1 catalyst exhibits a high content of lattice oxygen and efficient lattice oxygen migration. These properties further supply active oxygen for the NOx-assisted soot oxidation mechanism. This study offers a valuable, simple, and cost-effective strategy for designing perovskite catalysts and efficiently removing PM particles.

Oxygen vacancy-mediated Mn2O3 catalyst with high efficiency and stability for toluene oxidation

Oxygen vacancy engineering in transition metal oxides is an effective strategy for improving catalytic performance. Herein, defect-enriched Mn2O3 catalysts were constructed by controlling the calcination temperature. The high content of oxygen vacancies and accompanying Mn4+ ions were generated in Mn2O3 catalysts calcined at low temperature, which could greatly improve the low-temperature reducibility and migration of surface oxygen species. DFT theoretical calculations further confirmed that molecular oxygen and toluene were easily adsorbed over defective α-Mn2O3 (222) facets with an energy of −0.29 and −0.48 eV, respectively, and corresponding OO bond length is stretched to 1.43 Å, resulting in the highly reactive oxygen species. Mn2O3-300 catalyst with abundant oxygen vacancies exhibited the highest specific reaction rate and lowest activation energy. Furthermore, the optimized catalyst possessed the outstanding stability, water tolerance and CO2 yield. In comparison with the fresh Mn2O3-300 catalyst, the physical structure and surface property of the used catalyst remained almost unchanged regardless of whether undergoing the stability test at consecutive catalytic runs as well as high temperature, and water resistance test. In situ DRIFTS spectra further elucidated that introducing the water vapor had little effect on the reaction intermediates, indicating the excellent durability of the defect-enriched catalyst.

Insights into the catalytic mechanism of V-Mo@CN for the oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

The efficient synthesis of 2, 5-diformylfuran (DFF) over non-noble metal catalysts has been a significant challenge in biomass conversion strategies. Herein, a bimetallic V-Mo oxide supported by nitrogen-doped carbon (V-Mo@CN) was fabricated for the efficient oxygenation of 5-hydroxymethylfurfural (HMF) towards DFF. Remarkably, under the optimal conditions, a full conversion of HMF was achieved with an impressive DFF yield of 97.1 %. This oxidation reaction was determined to be a first-order reaction with a relatively lower apparent activation energy of 46.76 kJ/mol and proceeded by the synergistic redoxes of V5+/V3+ and Mo6+/Mo4+ with the assistance of the highly mobile lattice oxygen. The synergism of the V-species, Mo-species and @CN support contributed to the high-efficiency oxidation of HMF to generate DFF. The synergistic action of the V-species and O-species was responsible for the competitive adsorption advantage of the C-OH in HMF with a vertical configuration, ensuring the highly selective and efficiency in oxidizing HMF toward DFF.

Against catalyst deactivation during toluene oxidation on CuCeOx in flue gas: High oxidation efficiency and rapid oxidation pathway

The removal of volatile organic compounds (VOCs) from flue gas by a tightly coupled catalytic oxidation process in the NH3-SCR unit is a cost-effective approach. A CuCeOx bimetallic mixed oxide catalyst prepared by the co-precipitation method has demonstrated the ability to completely convert toluene at 350 ℃ under simulated flue gas conditions. Cu oxide is considered as the main active site for toluene oxidation, and the introduction of Ce induced a synergistic effect which enhanced the surface adsorbed oxygen and oxidation performance. The CuCeOx catalyst was found to outperform commercial VOC catalysts (Pt/Al2O3) and SCR catalysts (V2O5-WO3/TiO2) under the influence of different flue gas components. The negative effect of the flue gas on CuCeOx almost diminished at 350 ℃. The mechanism study showed that toluene on CuCeOx underwent a rapid oxidation pathway, thereby avoiding the potential interaction between intermediates and flue gas components. The superior catalytic performance of CuCeOx in the simulated flue gas conditions were attributed to the higher toluene adsorption efficiency and weaker adsorption towards the flue gas components.

Tuning Surface Electronics State of P-Doped In2.77S4/In(OH)3 toward Efficient Photoelectrochemical Water Oxidation.

Indium sulfide with a two-dimensional layered structure offers a platform for catalyzing water oxidation by a photoelectrochemical process. However, the limited hole holders hinder the weak intrinsic catalytic activity. Here, the nonmetallic phosphorus atom is coordinated to In2.77S4/In(OH)3 through a bridge-bonded sulfur atom. By substituting the S position by the P dopant, the work function (surface potential) is regulated from 445 to 210 mV, and the lower surface potential is shown to be beneficial for holding the photogenerated holes. In2.77S4/In(OH)3/P introduces a built-in electric field under the difference of Fermi energy, and the direction is from the bulk to the surface. This band structure results in upward band bending at the interface of In2.77S4/In(OH)3 and P-doped sites, which is identified by density functional theory calculations (∼0.8 eV work function difference). In2.77S4/In(OH)3/P stands out with the highest oxidation efficiency (ηoxi = 70%) and charge separation efficiency (ηsep = 69%). Importantly, it delivers a remarkable water oxidation photocurrent density of 2.51 mA cm-2 under one sun of illumination.

Mechanical agitation and ultrasound constructed in situ Fenton system: The role of atomic hydrogen for Fe(III) reduction

It has been reported that the ultrasonic agitation coupled system (US/A) has higher oxidation efficiency than the pure ultrasonic system (US), and the atomic hydrogen (H) and hydroxyl radicals (OH) produced by H2O cracking and in situ hydrogen peroxide (H2O2) can be significantly detected. In order to utilize the residual H2O2 and explore the role and fate of H, US/A/Fe(III) as an in situ Fenton oxidation system, was constructed in this study. The experimental results proved that the system can generate H2O2in situ, and adding Fe(III) could significantly promote the oxidation of refractory organic pollutants. Quenching tests, probes experiments and EPR test were performed to successfully monitor the existence of OH. The contribution of H to Fe(III) reduction was speculated and confirmed. In addition, the kinetic model showed the decomposition rate of water molecule and the reduction rate of Fe(III) by H under different ultrasonic power. The effects of the factors (pH, coexisting substance, and actual water environment) on degrading organic pollutants were evaluated. Therefore, this work provides new strategy and mechanistic insight into in situ Fenton technique by coupling ultrasonic agitation and Fe(III) without external oxidants.

Microbubble-assisted liquid oxidation for efficient one-step phase decomposition and recovery of V and Cr from vanadium slag

Oxidation roasting is an effective way to recover vanadium (V) and chromium (Cr) from vanadium slag but is severely limited by carbon reduction and energy conservation. Herein, a novel method is proposed employing a microbubble-assisted liquid phase oxidation technique , the recovery efficiencies of V and Cr reached 94.11 % and 80.27 %, respectively. The decomposition and oxidization mechanisms of low-valent V and Cr spinels were investigated. Leaching kinetics analyzes demonstrated that microbubbles effectively enrich hydroxide ions on the solid surface and disrupt diffusion resistance, promoting adequate exposure of spinel. The UV and XPS results revealed that the Cr(VI) proportion increased to 12.30 % and 97.2 %, respectively, in tailings and leachate. More importantly, hydroxyl radicals (·OH) were detected during the leaching process, confirming the performance of the self-catalytic oxidation reaction. These discoveries offer a novel pathway with high oxidation efficiency, low energy consumption, and more environmental friendliness for recycling valuable metals from amphoteric mineral resources.

Preparation of catalyst of cobalt‐ and/or iron‐doped strontium zirconate and its performance in removal of m‐cresol using ozone as oxidant

AbstractBACKGROUNDWastewater containing m‐cresol has become a global water environmental problem because its degradation is difficult, and it is highly toxic to plants, animals, and humans. The heterogeneous catalytic ozonation process has been widely used in the treatment of environmental pollution, so it is very important to study efficient catalysts. Perovskite catalysts have been widely investigated and applied in catalytic ozonation processes. Among them, strontium zirconate is a promising perovskite catalyst owing to its high oxidation efficiency and environmental friendliness.RESULTSStrontium zirconate was successfully synthesized via the co‐precipitation method. To improve strontium zirconate catalytic performance, some methods such as changing the doping ratio of cobalt and iron, changing the amount of polyethylene glycol added, changing the calcination temperature, and changing the aging time were carried out during the synthesis process. Finally, the optimal conditions were determined. 0.4 g L−1 Sr2Co0.4Fe0.6ZrO6 prepared under the optimal conditions was used for catalytic ozonation of 100 ppm m‐cresol, which achieved the optimum degradation (0.136 min−1), m‐cresol conversion rate (92.2%) and total organic carbon removal rate (12.1%) within 20 min.CONCLUSIONThis work provides the best preparation conditions. The Sr2Co0.4Fe0.6ZrO6 catalyst, as prepared, is the optimal catalyst for catalytic ozonation of m‐cresol among the investigated Sr2CoxFe1−xZrO6 catalysts. © 2024 Society of Chemical Industry (SCI).

Experimental and numerical investigation of methane combustion in a HCCI engine under enriched oxygen conditions

The challenge in the energy transition lies in the intermittent nature of renewable energy, requiring the development of effective storage methods. E-fuels are considered a promising solution, with potential applications to Homogeneous Charge Compression Ignition (HCCI) engines known for their high thermal efficiency and low nitrogen oxide emissions. However, HCCI engines face limitations such as low power density and a narrow operating range. To overcome these issues, oxygen-enriched combustion is proposed, aiming at enhancing the mixture reactivity and expanding the operating range by decreasing the intake temperature. As the potential of the expansion of the operating range has never been investigated, we performed an experimental campaign using a methane-fuelled HCCI engine at variable oxygen fractions in the oxidizer. To further elucidate the effects of oxy-fuel combustion, we also performed a kinetic analysis of the reactions driving the combustion behaviour. It has been experimentally found that increasing the oxygen content in the mixture, up to 90%, has a significant potential to decrease the needed intake temperature (up to 70 °C) of the charge to keep the Maximum Pressure Rise Rate (MPRR) below the safety threshold of 8 bar/CAD. Despite the notable IMEP increase achieved, operating the engine at high oxygen content presents significant technical challenges. Therefore, to make HCCI engines competitive with other combustion modes, it is essential to combine oxygen enrichment with additional power density enhancement techniques. The kinetic analysis has highlighted that the mixture is less sensitive to intake temperature changes at higher oxygen percentages (above 50%) and that the rates of the main reactions involved in methane and OH consumption are highly enhanced by oxygen addition.

Integration of surface polymerization and self-assembly strategies for heterogenization of copper-based catalysts for water oxidation

Integration of surface polymerization and self-assembly strategies for heterogenization of copper-based catalyst leads to sustainable high efficiency for water oxidation.

Oxygen vacancies tuning over Co3O4 nanosheet preferentially growing (2 2 0) facet for efficient Hg0 removal from flue gas

Oxygen vacancy is very important for the Hg0 oxidation process due to it can capture and activate gaseous oxygen forming surface chemisorbed oxygen to oxidize Hg0 to HgO. Precise control of oxygen vacancies amount is a big challenge in this field. For Co3O4, oxygen vacancy can be generated by Co3+ reduction to Co2+ and Co3+ mainly exist in (220) facet. Thus, in the present work, Co3O4 nanosheets preferentially growing (220) facet with more Co3+ were synthesized and CO was used as reduction agent to reduce Co3O4 at different reduction condition. After that, Co3O4 nanosheets with different amount of oxygen vacancies were obtained. XPS, Raman and PL results show that, the amount of oxygen vacancies increase firstly and then decrease with the increase of reduction temperature and time. CO can reduce Co3+ to Co2+ forming oxygen vacancies. However, when the reduction temperature and time are at a high level, Co3O4 will be over reduced to CoO leading to a decrease of oxygen vacancies. DFT confirm that, when Co3O4 is over reduced, O2 will hard to adsorb on Co3O4 surface and lattice oxygen will be formed even after O2 adsorption. Co3O4-Te300Ti2 has an optimal reduction degree leading to higher oxygen vacancy concentration and better O2 adsorption and activation ability. Therefore, Co3O4-Te300Ti2 has a high Hg0 oxidation efficiency which is over 96 % in a wide temperature range of 150–300 °C at a high GHSV of 180,000 h−1.

Highly Dispersed Pt on Ceria with N-Doped Carbon As High Durable Catalyst for ORR and High Tolerant to H2s and CO for HOR in PEMFCs

Proton Exchange Membrane Fuel Cells (PEMFCs) are one of the most promising clean and efficient energy conversion devices. However, carbon supported Pt-based electrocatalysts, widely used in PEMFCs, show poor stability due to the carbon oxidation and unstable Pt in practical application. Hydrogen starvation at anode and unprotected startup/shutdown of PEMFCs can arouse high potential over 1.3V resulting in severe carbon corrosion and irreversible performance loss. With increased electron conductivity, the doped metal oxides Ti3O5Mo0.2Si0.4 (TOMS) [1], Nb-TiO2 [ 2], Ta0.3Ti0.7O2 [ 3], Sb-SnO2 [ 4], W-SnOx and TiOx [ 5] show great potential as durable catalyst supports that can stand over 1.0V for PEMFCs. Furthermore, strong metal support interactions (SMSI) of Pt and the support also enhance the stability of Pt.CeO2 which exhibits good dynamic oxygen storage and release capacity, strong redox capacity, was deposited on N-doped carbon (NC) as support. Pt was highly dispersed on the CeO2/NC to form Pt/CeO2/NC catalyst. Accelerated degradation test (ADT) was carried out by sweeping voltage from 1.0V to 1.2V on a GC disk with a Pt loading of 20 μgPt·cm-2 in the oxygen saturated 0.1M HClO4 electrolyte with a scan rate of 10mV·s-1, while the Pt ring was held at 1.2V vs. RHE. Fig 1 shows the morphology of as-prepared CeO2/NC and Pt/CeO2/NC, the LSV and CV of Pt/CeO2/NC after different cycles of ADT. The specific mass activity at 0.9ViR free (im@0.9V) for oxygen reduction reaction (ORR) of Pt/CeO2/NC was 105mA×mg-1 and slightly increased about 8% after 10000 cycles.On the other hand, precious metal on CeO2 is high efficient CO oxidation catalyst [6-7] and widely applied for H2 purification from reformate gases. CeO2 was applied as H2S oxidant [8] too. This broadens the Pt/CeO2/NC as a high H2S and CO tolerant catalyst for hydrogen oxidation reaction (HOR). The high dispersion of Pt nano particle, the interaction between the poison gases and Pt and/or CeO2 was believed to contribute. The theoretical and experimental details will be presented at the symposium.Reference A. M. Esfahani, E. B. Easton. Applied Catalysis B: Environmental, 2020, 268, 118743.H. Cheng, Sankarasubramanian, I. Matanovic, P. Atanassov, V. Ramani. ChemSusChem, 2019, 12, 3468. Kumar, V. Ramani. ACS Catal. 2014, 4, 1516.Ozouf, G. Cognard,F. Maillard, M. Chatenet, L. Gu´etaz,M. Heitzmann, P. A. Jacques, C. Beauger. J. Electrochem. Soc., 2019, 165(6), F3036.T. Arai, O. Takashi, K. Amemiya, T. Takahashi. SAE Int. J. Alt. Power. 2017, 6 (1), 145.Y. Kardash1, E. A. Derevyannikova, E. M. Slavinskaya, A. I. Stadnichenko, V. A. Maltsev, A. V. Zaikovskii, S. A. Novopashin, A. I. Boronin1, K. M. Neyman. Frontiers in Chemistry, 2019, 7, 114. Maurer, J. Jelic, J. Wang, A. Gänzler, P. Dolcet, C. Wöll, Y. Wang, F. Studt, M. Casapu, J. Grunwaldt. Nature Catalysis, 2020, 3, 824.X. Zheng, Y. Li, L. Zhang, L. Shen, Y. Xiao, Y. Zhang,C. Au, L. Jiang. Applied Catalysis B: Environmental, 2019, 252, 98. Figure 1

Paint sludge derived activated carbon encapsulating with cobalt nanoparticles for non-radical activation of peroxymonosulfate

Industrial solid waste management and recycling are important to environmental sustainability. In this study, cobalt (Co) nanoparticles encapsulated in paint sludge-derived activated carbon (AC) were fabricated. The Co-AC possessed high conductivity, magnetic properties and abundant metal oxide impurities (TiAlSiOx), which was applied as multifunctional catalyst for peroxymonosulfate (PMS) activation. Compared to pure AC, the Co-AC exhibited significant enhanced performance for degradation of tetracycline hydrochloride (TCH) via PMS activation. Mechanism studies by in situ Raman spectroscopy, Fourier infrared spectroscopy, electrochemical analysis and electron paramagnetic resonance suggested that surface-bonded PMS (PMS*) and singlet oxygen (1O2) are the dominant reactive species for TCH oxidation. The non-radical species can efficiently oxidize electron-rich pollutants with high efficiency, which minimized the consumption of PMS and the catalyst. The removal percentages of TCH reached 97 % within 5 min and ∼ 99 % within 15 min in the Co-AC/PMS system. The Co active sites facilitated PMS adsorption to form the PMS* and the TiAlSiOx impurities provided abundant oxygen vacancy for generation of the 1O2. In addition, the Co-AC/PMS system achieved high efficiency and stability for oxidation of the target pollutants over a long-term continuous operation. This work not only offers a cost-effective approach for recycling industrial waste but also provides new insights into the application of waste-derived catalyst for environmental remediation.

Microenvironment tailoring mediated oxygen-vacancy defect engineering strategy facilitating O2 and alcohol activation on HEOs with superior catalytic efficiency

Achieving selective oxidation of biomass-derived benzyl alcohol under a mild environment to prepare high-value-added oxygenates is an attractive goal but remains a significant challenge in the absence of qualifying catalysts. Herein, we propose a microenvironment modulation mediated oxygen-vacancy defect engineering for piloting the benzyl alcohol oxidation on catalyst MW-HEO. Collective characterizations indicate that the contemporary tactic can modulate the catalyst's pore structure and surface electronic states and form massive oxygen vacancies. Both density functional theory (DFT) simulations and experimental results conclusively reveal that the oxygen vacancies contribute to the O2 activation and forming active radicals, thus facilitating the deeper reactant activation and enabling the subsequent oxidation reactions to proceed feasibly. This work lays a solid foundation for microenvironment regulation-mediated oxygen vacancy defect engineering for the high-efficiency oxidation catalysis of benzyl alcohol and a series of alcohol derivatives.