Electron Transfer Oxidation Research Articles

Class Ib Ribonucleotide Reductases: Activation of a Peroxido-MnIIMnIII to Generate a Reactive Oxo-MnIIIMnIV Oxidant.

In the postulated catalytic cycle of class Ib Mn2 ribonucleotide reductases (RNRs), a MnII2 core is suggested to react with superoxide (O2·-) to generate peroxido-MnIIMnIII and oxo-MnIIIMnIV entities prior to proton-coupled electron transfer (PCET) oxidation of tyrosine. There is limited experimental support for this mechanism. We demonstrate that [MnII2(BPMP)(OAc)2](ClO4) (1, HBPMP = 2,6-bis[(bis(2 pyridylmethyl)amino)methyl]-4-methylphenol) was converted to peroxido-MnIIMnIII (2) in the presence of superoxide anion that converted to (μ-O)(μ-OH)MnIIIMnIV (3) via the addition of an H+-donor (p-TsOH) or (μ-O)2MnIIIMnIV (4) upon warming to room temperature. The physical properties of 3 and 4 were probed using UV-vis, EPR, X-ray absorption, and IR spectroscopies and mass spectrometry. Compounds 3 and 4 were capable of phenol oxidation to yield a phenoxyl radical via a concerted PCET oxidation, supporting the proposed mechanism of tyrosyl radical cofactor generation in RNRs. The synthetic models demonstrate that the postulated O2/Mn2/tyrosine activation mechanism in class Ib Mn2 RNRs is plausible and provides spectral insights into intermediates currently elusive in the native enzyme.

Engineering the surface properties of CeVO4 catalysts to improve low temperature De-NOx performance through regulating pH value in synthesis process

The presence of quick electron transfer in metal oxides can well promote selective catalytic reduction (SCR) of NOx with NH3. Here, a series of CeVO4-X (X = 4, 6, 8, 10 and 12) catalysts with engineering the surface properties were successfully synthesized via controlling pH values in the hydrothermal process. The catalysts were evaluated in the NH3-SCR reaction in the temperature range of 90–420 °C. Among them, the CeVO4-8 catalyst with nanorods structure displayed the highest catalytic activity, achieving over 90 % NO conversion between 180 and 390 °C. It also showed high N2 selectivity and good tolerance to H2O and SO2. The effect of different pH values on the catalytic activity and microstructure of CeVO4 catalysts was comprehensively characterized using various techniques such as XRD, Raman, SEM, HR-TEM, N2 adsorption-desorption, H2-TPR, O2/NH3/NO-TPD, XPS, and in-situ DRIFTS. The characterization results revealed that the variation in catalytic activity among these catalysts is attributed to the difference in their surface properties, which were tuned by changing the pH values during synthesis process, despite having the same crystal phase of CeVO4. The superior catalytic performance of the CeVO4-8 catalyst, particularly at low temperature, can be attributed to its higher specific surface area, enhanced acidity, and the electron transfer between cerium and vanadium species (Ce4+ + V4+ ↔ Ce3+ + V5+), consequently resulting in increased redox capacity and facilitating the adsorption and activation of NH3 and NO molecules. This study broadens the applications of CeVO4 in the field of low temperature NOx removal.

In-situ construction of nitrogen-doped porous carbon nanosheets supported well-dispersed Fe3O4 nanoparticles for efficient purification of antibiotic wastewater via peroxydisulfate activation

Heterogeneous catalysts composed of transition metal oxides and carbon-based materials have displayed significant potential in persulfates activation for the elimination of diverse refractory organic pollutants. Herein, the nitrogen-doped porous carbon (N-pC) nanosheets supported well-dispersed Fe3O4 nanoparticles (Fe3O4/N-pC) were meticulously designed and fabricated. This fabrication process involved the creation of Fe3+/(CN@PDA) precursor through loading polydopamine-Fe3+ complex on graphitic carbon nitride (g-C3N4) and the following calcination process, resulting in in-situ formation of Fe3O4 nanoparticles on the N-pC nanosheets that were derived from polydopamine coated g-C3N4. The large specific surface area, coupled with accessible Fe2+/Fe3+ species, facilitated the synergy of adsorption and catalysis, enabling the rapid elimination of antibiotics via peroxydisulfate (PDS) activation. The optimal Fe3O4/N-pC catalyst demonstrated a remarkable efficacy in the degradation of tetracycline-hydrochloride (TC), reaching a quasi-first-order kinetic constant of 0.1479 min−1, which was 1.95 times that of the degradation reaction using g-C3N4 (0.0758 min−1). Mechanistic investigations revealed that both radicals (·O2-,·OH and SO4·-) and non-radical (1O2 and electron transfer) oxidation pathways were involved in TC degradation. The toxicities of degradation intermediates were assessed through a bean-sprout planting experiment and the quantitative structure-activity relationship (QSAR) analysis. This work offers some guidance on the preparation and application of heterogeneous catalysts for effectively removing organic contaminants from water.

Evaluation of the photosensitizer activity of hydrophobic phosphorus(V)porphyrins using the absorption spectral change of 1-benzyl-1,4-dihydronicotinamide

Under visible light irradiation, water-insoluble P(V)porphyrins oxidized 1-benzyl-1,4-dihydronicotinamide (BNADH), a model compound for nicotinamide adenine dinucleotide, and diminished the typical absorption of BNADH at around 340 nm. A singlet oxygen quencher, sodium azide, partially inhibited photosensitized BNADH oxidation. This BNADH oxidation photosensitized by P(V)porphyrins in the presence of sodium azide can be explained by electron transfer oxidation from BNADH to the photoexcited P(V)porphyrins. The quantum yields of BNADH oxidation via electron transfer by these P(V)porphyrins were larger than those of a singlet oxygen mechanism. Redox potential measurements supported the electron transfer mechanism from a thermodynamic point of view, and fluorescence lifetime measurement also suggests this mechanism. The process of this electron transfer oxidation involves the radical formation of BNADH and the further reaction of this radical to the oxidized form (cationic form of BNADH). Analysis of the quantum yields of BNADH photooxidation by P(V)porphyrins suggests that the photoinduced electron transfer from BNADH to photoexcited P(V)porphyrins triggers the radical chain reaction of BNADH oxidation. The electron transfer rate coefficient and this efficiency were increased with an increase in the Gibbs energy of electron transfer from tryptophan to photoexcited P(V)porphyrins (−ΔG). However, the BNADH oxidation quantum yield via electron transfer decreased with an increase in the -ΔG of electron transfer. These results suggest that reverse electron transfer inhibits the decomposition of BNAD radicals. This assay using BNADH can be used to evaluate the photosensitizer activity of water-insoluble compounds. These P(V)porphyrins may be used as photosensitizers for photodynamic therapy in a relatively hydrophobic environment in cancer tissues.

Interplay of two low-barrier hydrogen bonds in long-distance proton-coupled electron transfer for water oxidation.

D1-Tyr161 (TyrZ) forms a low-barrier H-bond with D1-His190 and functions as a redox-active group in photosystem II. When oxidized to the radical form (TyrZ-O•), it accepts an electron from the oxygen-evolving Mn4CaO5 cluster, facilitating an increase in the oxidation state (Sn; n = 0-3). In this study, we investigated the mechanism of how TyrZ-O• drives proton-coupled electron transfer during the S2 to S3 transition using a quantum mechanical/molecular mechanical approach. In response to TyrZ-O• formation and subsequent loss of the low-barrier H-bond, the ligand water molecule at the Ca2+ site (W4) reorients away from TyrZ and donates an H-bond to D1-Glu189 at Mn4 of Mn4CaO5 together with an adjacent water molecule. The H-bond donation to the Mn4CaO5 cluster triggers the release of the proton from the lowest pKa site (W1 at Mn4) along the W1…D1-Asp61 low-barrier H-bond, leading to protonation of D1-Asp61. The interplay of the two low-barrier H-bonds, involving the Ca2+ interface and forming the extended Grotthuss-like network [TyrZ…D1-His190]-[Mn4CaO5]-[W1…D1-Asp61], rather than the direct electrostatic interaction, is likely a basis of the apparent long-distance interaction (11.4 Å) between TyrZ-O• formation and D1-Asp61 protonation.

PSXIV-26 Live Animal Longissimus Thoracis Mitochondrial Capacities at 10, 13, and 18 Months of Age Are Related to Meat Quality in Angus and Brahman Steers

Abstract Mitochondrial abundance and efficiency correlate with meat color, but relationships between live animal mitochondria and other markers of beef quality remain largely unknown. To test the hypothesis that live animal skeletal muscle mitochondrial markers would be correlated with post-harvest hot carcass weight, ribeye area, calculated yield grade, backfat thickness, and marbling, samples were collected from the longissimus thoracis of Brahman and Angus steers at 10 mo (25 Angus, 23 Brahman), 13 mo (35 Angus, 33 Brahman), and 18 mo (35 Angus, 33 Brahman) of age. Mitochondrial volume density and function were quantified by citrate synthase (CS) and cytochrome c oxidase activities, respectively. Mitochondrial oxidative phosphorylation (OxP) and electron transfer (E) capacities were determined via high-resolution respirometry. Relationships between mitochondrial variables and carcass quality were determined using PROC CORR in SAS (v9.4). Within Angus at 10 mo, integrative (per mg tissue) complex I-supported OxP (PCI), maximal OxP (PCI+II), maximal E (ECI+II), and E supported by complex II (ECII) were positively correlated with hot carcass weight (P ≤ 0.05). Also, within 10 mo Angus, integrative OxPCI and flux control ratio (FCR) for OxPCI were positively correlated with backfat thickness (P ≤ 0.03). Within 10 mo Brahman, integrative PCI was positively correlated with ribeye area (P = 0.04). Within 13 mo Brahman, integrative mitochondrial proton LEAK was positively correlated with hot carcass weight (P = 0.02) and intrinsic (relative to CS activity) LEAK, PCI, and ECI+II were positively correlated with marbling (P ≤ 0.05). Conversely, CS activity was negatively correlated with marbling in 13 mo Brahman (P = 0.05). Integrative, FCR, and intrinsic LEAK were negatively correlated with ribeye area (P ≤ 0.05) but positively correlated with calculated yield grade in 13 mo Angus (P ≤ 0.03). However, at 18 mo, integrative, FCR, and intrinsic LEAK were positively correlated with ribeye area (P ≤ 0.008) but negatively correlated with calculated yield grade (P ≤ 0.01) in Angus steers. Furthermore, integrative and intrinsic OxPCI+II, ECI+II, and ECII were positively correlated with marbling in 18 mo Angus (P ≤ 0.04). Within 18 mo Brahman, CS activity was positively correlated with ribeye area (P = 0.006). Cytochrome c oxidase activity was not correlated with any markers of meat quality. These results suggest that mitochondrial capacity for energy production in Angus and Brahman steers at different life and production stages may dictate potential for skeletal muscle growth and lipid metabolism leading to differences in beef quality at slaughter. This project was supported by USDA NIFA Award #2021-67015-33392.

Spatial confinement-regulated peroxymonosulfate activation to boost the generation of high-valent cobalt and radical species for achieving rapid removal of organic pollutants

It is of great significance to establish simple and effective methods to tackle water pollution problems. Herein, Co-loaded hollow carbon sphere (namely Co-HCS-1) served as PMS activation mediator was synthesized. The construction of hollow structure can improve specific surface areas and offer more active sites, thereby reducing electron transfer resistance and increasing contact among PMS, pollutant and catalyst. Hence, the Co-HCS-1-mediated direct electron-transfer oxidation between PMS and pollutant was enhanced. After embedding Co-based catalyst in the shell of hollow carbon sphere, hollow carbon shell will provide spatial confinement for Co-based catalyst, which shortened mass transfer process. Thus, spatial confinement effect originating from carbon sphere can accelerate the charge transfer between PMS and active sites of Co-HCS-1, thereby promoting O-O bond cleavage of PMS. As a result, the generations of radicals and high-valent metal complexes (namely Co-HCS-1≡Co4+) were boosted. Under the combined effects of electron-transfer oxidation, reactive oxygen species and Co-HCS-1≡Co4+, more than 90 % of typical organic pollutants can be removed from simulated wastewater within 5 min by Co-HCS-1/PMS system, and a high removal efficiency of total organic carbon can also be realized. To sum up, current work provided a valuable reference for the preparation and application of catalyst with high activity in PMS activation.

Impact of Varying the Photoanode/Catalyst Interfacial Composition on Solar Water Oxidation: The Case of BiVO4(010)/FeOOH Photoanodes.

Photoanodes used in a water-splitting photoelectrochemical cell are almost always paired with an oxygen evolution catalyst (OEC) to efficiently utilize photon-generated holes for water oxidation because the surfaces of photoanodes are typically not catalytic for the water oxidation reaction. Suppressing electron-hole recombination at the photoanode/OEC interface is critical for the OEC to maximally utilize the holes reaching the interface for water oxidation. In order to explicitly demonstrate and investigate how the detailed features of the photoanode/OEC interface affect interfacial charge transfer and photocurrent generation for water oxidation, we prepared two BiVO4(010)/FeOOH photoanodes with different Bi:V ratios at the outermost layer of the BiVO4 interface (close to stoichiometric vs Bi-rich) while keeping all other factors in the bulk BiVO4 and FeOOH layers identical. The resulting two photoanodes show striking differences in the photocurrent onset potential and photocurrent density for water oxidation. The ambient pressure X-ray photoelectron spectroscopy results show that these two BiVO4(010)/FeOOH photoanodes show drastically different Fe2+:Fe3+ ratios in FeOOH both in the dark and under illumination with water, demonstrating the immense impact of the interfacial composition and structure on interfacial charge transfer. Using computational studies, we reveal the effect of the surface Bi:V ratio on the hydration of the BiVO4 surface and bonding with the FeOOH layer, which in turn affect the band alignments between BiVO4 and FeOOH. These results explain the atomic origin of the experimentally observed differences in electron and hole transfer and solar water oxidation performance of the two photoanodes having different interfacial compositions.

Applicability of Transition State Theory to the (Proton-Coupled) Electron Transfer in Photosynthetic Water Oxidation with Emphasis on the Entropy of Activation

Applicability of Transition State Theory to the (Proton-Coupled) Electron Transfer in Photosynthetic Water Oxidation with Emphasis on the Entropy of Activation

Stereoselective Photoredox Catalyzed (3+3) Dipolar Cycloaddition of Nitrone with Aryl Cyclopropane

AbstractBy resorting to the principle of remote activation, we herein demonstrate the first photoredox catalyzed (3+3) dipolar cycloaddition of nitrones with aryl cyclopropanes. Key to the fidelity of the reaction resides in a facile manner of substrate activation by single‐electron transfer (SET) oxidation with photoredox catalysis, and the reaction takes place through a stepwise cascade encompassing a three‐electron‐type nucleophilic substitution triggered cyclopropane ring‐opening and a diastereoselective 6‐endo‐trig radical cyclization manifold. The reaction proceeds under mild conditions with excellent regio‐ and stereoselectivity, nicely complementing the well‐developed Lewis acid catalyzed cycloaddition of donor‐acceptor cyclopropanes. Other merits of the protocol include wide scope of aryl cyclopropanes with diversified substitution patterns and good functional‐group compatibility. A mechanism involving an aryl radical cation promoted remote activation mode was also proposed and supported by mechanistic experiments.

Stereoselective Photoredox Catalyzed (3+3) Dipolar Cycloaddition of Nitrone with Aryl Cyclopropane.

By resorting to the principle of remote activation, we herein demonstrate the first photoredox catalyzed (3+3) dipolar cycloaddition of nitrones with aryl cyclopropanes. Key to the fidelity of the reaction resides in a facile manner of substrate activation by single-electron transfer (SET) oxidation with photoredox catalysis, and the reaction takes place through a stepwise cascade encompassing a three-electron-type nucleophilic substitution triggered cyclopropane ring-opening and a diastereoselective 6-endo-trig radical cyclization manifold. The reaction proceeds under mild conditions with excellent regio- and stereoselectivity, nicely complementing the well-developed Lewis acid catalyzed cycloaddition of donor-acceptor cyclopropanes. Other merits of the protocol include wide scope of aryl cyclopropanes with diversified substitution patterns and good functional-group compatibility. A mechanism involving an aryl radical cation promoted remote activation mode was also proposed and supported by mechanistic experiments.

Shifting CO2 hydrogenation from producing CO to CH3OH by engineering defect structures of Cu/ZrO2 and Cu/ZnO catalysts

The catalytic performance of supported Cu catalysts in CO2 hydrogenation is structurally dependent; hence, regulating the metal-support interactions, often driven by the redox feature of the metal oxide supports, can potentially improve catalytic performance. In this work, we demonstrate an enhanced strong metal-support interaction (SMSI) and electronic metal-support interaction (EMSI) in Cu/ZrO2 and Cu/ZnO after introducing oxygen vacancies into the catalyst supports, evidenced by more Cu encapsulation by oxide overlayers and electron transfer from the defective supports to Cu after introducing the oxygen vacancies. As a result, the defective Cu/ZrO2 and Cu/ZnO catalysts showed markedly improved MeOH production rather than CO production in the CO2 hydrogenation reaction. The in situ FTIR studies showed that the CO2 molecules preferentially adsorbed and activated into bicarbonate rather than carbonate, followed by a rapid conversion into formate on the defective catalyst. These findings highlight the special effects of defective supports in CO2 activation and conversion and catalyst design and synthesis.

Electrochemical activation of peroxydisulfate using an IrO2 electrode for the efficient degradation of acid orange 74: Mechanisms of different activation methods

Electrochemical activation of persulfate is an efficient and green technology. In this study, the differences in the pollutant degradation efficiency and peroxydisulfate (PDS) activation mechanism were compared via electrochemical activation of PDS using only an IrO2 anode, an IrO2 cathode, and both an IrO2 anode and stainless steel (SS) cathode. In these methods, the degradation of acid orange (AO) 74 conformed to the pseudo-first-order kinetic degradation model. The electrochemical activation of PDS using an IrO2 anode resulted in the highest AO 74 degradation efficiency of 81.7 % with a degradation rate constant of 0.58 h−1. The results of radical quenching and cyclic voltammetry indicated that during the electrochemical activation of PDS using an IrO2 anode, direct electron transfer and nonradical oxidation contributed to AO 74 degradation. Using an IrO2 cathode, the contribution to AO 74 degradation was mainly OH, while using an IrO2 anode and SS cathode, the contribution was the joint action of the nonradical and radical oxidation. Furthermore, during the electrochemical activation of PDS using an IrO2 anode, the degradation rate exhibited a good linear relationship with the current density and PDS concentration. The addition of Cl− considerably enhanced AO 74 degradation.

Efficient sulfamethoxazole degradation via boosting nonradical-based peroxymonosulfate activation by biochar supported Co-Ni bimetal oxide

Nonradical-based peroxymonosulfate (PMS) activation has recently caught increasing attention due to its less susceptible to environmental interference in the complex water matrix, but the performance of activators still requires further development for efficient pollutants degradation in wastewater treatment. Herein, a novel Co-Ni bimetal oxide loaded biochar was fabricated to boost nonradical PMS activation for enhancing sulfamethoxazole (SMX) degradation. According to the results, the as-obtained catalyst exhibited excellent SMX degradation efficiency of 96.2% within 30 min through complete nonradical oxidation pathway (including both 1O2 and mediated electron transfer). Co was confirmed to be the active sites to generate 1O2 dominated nonradical pathway. The biochar acted as the porous material to achieve the electron transfer oxidation process, as well as Ni ensured sufficient electron transfer rate and bound Co active sites to prevent the leaching of metal ions. Meanwhile, the prepared Co-Ni bimetal oxide loaded biochar possessed a remarkable catalytic degradation durability in the complex water environment conditions and showed universality for various organic contaminants. This study offers a valuable clue on the rational design of novel catalyst to induce the nonradical pathway-based persulfate activation.

Tunable peroxymonosulfate activation by ( −1 1 1) crystal plane exposed δ-MnO2: Oxidant concentration induced intrinsic mechanisms transformation

The dual role of manganese oxides in peroxymonosulfate (PMS) activation for the degradation of organic contaminants makes the mechanism investigation complicated. Herein, a (−111) crystal plane exposed δ-MnO2 (SN-KMO) was synthesized to decipher the debate between direct oxidation process (DOP) and electron transfer process (ETP) mechanisms. Generally, 5 mg/L bisphenol A (BPA) could be efficiently removed in 15 min regardless of in the presence of high (0.5 mM) or low (0.05 mM) PMS concentration. Mechanisms analysis showed that nonradical pathways of DOP and ETP simultaneously contributed to the BPA degradation without the participation of radicals oxidation. Yet, contributions of DOP and ETP at certain PMS dosages differed significantly. Specifically, at high PMS concentration of 0.5 mM, DOP played the dominant role, and the overly protonated manganese active sites could bond with O-O bridged species derived from two PMS molecules to form outer-sphere complexes. Comparatively, at low PMS concentration of 0.05 mM, BPA oxidization was primarily dominated by ETP. The specific ETP was highly dependent on solution pH, and it only existed in the presence of high PMS concentration. The significance of this work lies in synthesizing a (−111) crystal plane exposed δ-MnO2 for efficient BPA degradation with low PMS dosage (0.05 mM) and discovering the unreported outer-sphere complexes for understanding the PMS activation mechanisms by manganese oxides.

Bypassing mitochondrial defects rescues Huntington's phenotypes in Drosophila

Huntington's disease (HD) is a fatal neurodegenerative disease with limited treatment options. Human and animal studies have suggested that metabolic and mitochondrial dysfunctions contribute to HD pathogenesis. Here, we use high-resolution respirometry to uncover defective mitochondrial oxidative phosphorylation and electron transfer capacity when a mutant huntingtin fragment is targeted to neurons or muscles in Drosophila and find that enhancing mitochondrial function can ameliorate these defects. In particular, we find that co-expression of parkin, an E3 ubiquitin ligase critical for mitochondrial dynamics and homeostasis, produces significant enhancement of mitochondrial respiration when expressed either in neurons or muscles, resulting in significant rescue of neurodegeneration, viability and longevity in HD model flies. Targeting mutant HTT to muscles results in larger mitochondria and higher mitochondrial mass, while co-expression of parkin increases mitochondrial fission and decreases mass. Furthermore, directly addressing HD-mediated defects in the fly's mitochondrial electron transport system, by rerouting electrons to either bypass mitochondrial complex I or complexes III-IV, significantly increases mitochondrial respiration and results in a striking rescue of all phenotypes arising from neuronal mutant huntingtin expression. These observations suggest that bypassing impaired mitochondrial respiratory complexes in HD may have therapeutic potential for the treatment of this devastating disorder.

Hydrocarbon Oxidation by a Porphyrin-π-Cation Radical Complex.

Heme and chlorin π-cation radical oxidants are widely implicated in biological and synthetic oxidation catalysis. Little insight into the role of π-cation radicals in proton coupled electron transfer (PCET) oxidation is available. We prepared a NiII-porphyrin-π-cation complex ([NiII(P•+)]) and found it to be capable of the oxidation of a variety of simple hydrocarbon substrates. Interestingly, some of the products were hydroxylated, with ([NiII(P•+)]) working in concert with atmospheric O2 to yield hydroxylated hydrocarbons. Kinetic data suggested that the porphyrin-π-cation radical species oxidised substrates via a concerted PCET mechanism, where the nickel porphyrin-π-cation radical accepted the electron, and the proton was transferred to a free anion. Our findings highlight the potential role of π-cation radicals as hydrocarbon activators, demonstrating that porphyrin ligand non-innocence could be a readily manipulated resource for oxidation catalyst development.

Hydrocarbon Oxidation by a Porphyrin‐π‐Cation Radical Complex

AbstractHeme and chlorin π‐cation radical oxidants are widely implicated in biological and synthetic oxidation catalysis. Little insight into the role of π‐cation radicals in proton coupled electron transfer (PCET) oxidation is available. We prepared a NiII‐porphyrin‐π‐cation complex ([NiII(P⋅+)]) and found it to be capable of the oxidation of a variety of simple hydrocarbon substrates. Interestingly, some of the products were hydroxylated, with ([NiII(P⋅+)]) working in concert with atmospheric O2 to yield hydroxylated hydrocarbons. Kinetic data suggested that the porphyrin‐π‐cation radical species oxidised substrates through a concerted PCET mechanism, where the porphyrin‐π‐cation radical accepted the electron, and the proton was transferred to a free anion. Our findings highlight the potential role of π‐cation radicals as hydrocarbon activators, demonstrating that porphyrin ligand non‐innocence could be a readily manipulated resource for oxidation catalyst development.

Redox potentials of pollutants determining the dominate oxidation pathways in manganese single-atom catalyst (Mn-SAC)/peroxymonosulfate system: Selective catalytic mechanisms for versatile pollutants

Versatile persulfate-based catalytic mechanisms induced by highly-effective single atom catalysts (SACs) have been intensively reported, which was mainly ascribed to the versatile coordinated-structures of SACs. However, the origin of these different mechanisms from the specific properties of pollutants has been ignored. In this work, eight kinds of pollutants were selected and the half-wave potential (φ1/2) values representing their redox potentials were determined. A good correlation between the redox potential characteristics of pollutants and their oxidation performances/pathways in manganese single-atom catalyst (Mn-SAC)/PMS system can be confirmed. The φ1/2 values of different pollutants showed a good correlation with the energy gaps between the pollutants and Mn-SAC/PMS complexes as well as their electrophilicity indexes, which confirmed the redox potential of pollutants was essential to the electron-transfer oxidation in Mn-SAC/PMS system. Based on the new insights in this work, we will be able to unveil the sources of Fenton-like systems with tunable oxidation processes.

Highly efficient electrocatalytic oxidation of sterol by synergistic effect of aminoxyl radicals and SeNi5P4

AbstractThe exploration of efficient and environmentally friendly oxidation method is highly desirable to overcome the critical problems of poor selectivity and heavy metal contamination for the fine chemicals industry. Herein, a self‐supported three‐dimensional (3D) SeNi5P4 nanosheet electrocatalyst was rationally designed and fabricated. Benefiting from the synergistic effect of aminoxyl radical and mesoporous SeNi5P4/graphite felt (GF), an excellent performance of ≥98% selectivity and 33.12 kg (m−3 h−1) space–time yield was obtained for sterol intermediate oxidation with the enhanced mass transfer effect of the continuous flow system. The doping of anionic selenium and phosphorus modulated the electronic structure of SeNi5P4, and the oxyhydroxides generated by surface reconstruction accelerated the turnover of 2,2,6,6‐tetramethyl‐1‐piperidine N‐oxyl (TEMPO), thereby enhancing the intrinsic electrocatalytic activity. A scale‐up experiment was conducted with stacked‐flow electrolyzer demonstrated the application potential. This work provided an efficient synergistic electrocatalytic strategy to facilitate rapid electron and mass transfer for electrochemical alcohol oxidation and highlighted the potential for practical electrosynthesis applications.