Ultrafast O2 activation by copper oxide for 2,4-dichlorophenol degradation: The size-dependent surface reactivity

Highly Efficient Oxygen-Activated Self-Cleaning Membranes Prepared by Grafting a Metal–Organic Framework-Derived Catalyst

“…The results presented above indicated that copper nanoparticles could have destroyed O 2 molecules to yield ·O 2 – , 1 O 2 , and ·OH. Lower-reducing Cu(0) could not directly reduce O 2 to ROS, as previously reported, but could reduce O 2 to H 2 O 2 , while Cu(0) was simultaneously oxidized to monovalent or divalent copper (eqs and ); , Cu­(I) could have initiated the decomposition of H 2 O 2 to produce ·OH and convert O 2 to ·O 2 – , and Cu­(II) could also have been reduced to Cu­(I) by reaction with H 2 O 2 or ·O 2 – (eqs , , and ). , Both oxidation of ·O 2 – by ·OH and dimerization of ·O 2 – could have formed 1 O 2 , between which dimerization was determined to be the main pathway based on the results of free-radical quenching experiments (eqs and ). ,, The doping of Ni atoms to facilitate electron transfer further enhanced the catalytic activity, and for confirmation of this speculation, the electrochemical impedance spectral Nyquist plots of different membranes grafted with and without Ni-doped catalysts were obtained, and the results are shown in Figure S10, where it could be seen that the Ni-doped catalyst-grafted membranes exhibited smaller semicircles, indicating that the Ni-doped catalyst-grafted membranes possessed much lower resistance and faster electron transport could be achieved. − …”

“…To increase the fouling migration efficiency, numerous catalytic membranes have been successfully designed to activate powerful oxidants, such as ozone, hydrogen peroxide, chlorine/chlorine dioxide, and persulfate, and the generated ROS can degrade water pollutants and remove membrane foulants. ,,, Compared to the abovementioned strong oxidants, O 2 is a greener and more economical oxidant that could also theoretically be catalytically activated to produce ROS. To the best of our knowledge, few studies have combined membrane separation processes with catalytic oxidation using O 2 as the oxidant primarily because O 2 activation is a relatively difficult process; however, advances in the metal nanotechnology have facilitated the development of various metals/metal oxides (e.g., Cu(0), CuO, Fe(0), and Au) that can catalyze oxygen activation without the intervention of powerful oxidants and energy due to a high surface area-to-volume ratio, an abundance of surface active sites, and a unique electronic structure, − enabling membrane separation processes to be coupled with catalytic oxidation using O 2 as the oxidant.…”

Catalytic Oxygen Activation over the Defective CuO Nanoparticles for Ultrafast Dehalogenation

“…Thus, dehalogenation based on the nucleophilic O 2 •– provides an alternative route to degrade HOCs in the environment. Interfacial defect engineering, particularly for surface oxygen vacancies (OVs), can greatly promote surface electron transfer reactions and have recently triggered an explosion of studies. − These high-energy defects show an enhanced reactivity for spontaneous O 2 reduction without the consumption of external energies (e.g., light and electricity) to overcome the high energy barrier in O 2 activation . However, undesirable oxidative species (e.g., •OH and 1 O 2 ) are generated in such reaction systems along with O 2 •– , leading to inferior electron efficiency and potential disinfection byproduct formation. , Thus, although the efficient and selective conversion of O 2 to O 2 •– shows an application potential for HOC detoxification, the development of such dehalogenation systems remains a great challenge.…”

In Situ-Formed Phenoxyl Radical on the CuO Surface Triggers Efficient Persulfate Activation for Phenol Degradation

“…Persulfate-based advanced oxidation processes (PDS-AOPs) have been generally acknowledged as an effective method for pollutant degradation in water purification. , Among the numerous approaches for PDS activation to produce highly oxidative species (e.g., radicals, high-valent metal ions, and singlet oxygen), transition-metal-based activation was the most viable one owing to its low energy requirement, operational convenience, and high effectiveness. − Heterogeneous transition-metal oxides (M x O y ) have the advantages of low metal ion leaching and easy postreaction recovery as compared to the homogeneous metal ions (e.g., Fe 2+ and Cu 2+ ions), which showed potential applications for contaminant degradation in real water. − However, lower PDS-activation efficiency of M x O y compared to the homogeneous analogues remains challenging, and the limited understanding of the PDS activation mechanism at the molecular level poses a huge obstacle to the rational design of highly efficient M x O y catalysts.…”