Search

Highly dispersed framework Cu+/Cu2+ containing LaAlO 3 /Al 2 O 3 (La-Cu-Al) was synthesized by a solid-liquid mixed sol-gel method. Excessive Al 2 O 3 was confirmed to be necessary for the formation of LaAlO 3. The NMR, EXAFS, FTIR and element mapping results revealed that Cu+/Cu2+ preferred to substitute octahedral Al sites and bonded by Cu-O-Al in the lattice of LaAlO 3. Compared to La 2 CuO 4 , CuAl 2 O 4 and other reported Fenton-like catalysts, La-Cu-Al was more efficient to mineralize refractory pollutants at a wide pH range of 4.0–10.0. More single electrons around Cu center and octahedral Cu+ were confirmed to be responsible for the effective reduction of H 2 O 2 into powerful •OH. Moreover, organic pollutants as electron donors could interact with surface Cu to accelerate Cu2+/Cu+ cycle and affect O-O bond of H 2 O 2 on La-Cu-Al surface, further promoting the reduction of H 2 O 2 into •OH. These processes resulted in the high H 2 O 2 utilization and the highly efficient removal of pollutants on La-Cu-Al. [Display omitted] • Cu-LaAlO3/Al2O3 (La-Cu-Al) was fabricated by a solid-liquid mixed sol-gel method. • Cu preferred to substitute lattice octahedral Al sites of LaAlO3 with Al–O–Cu bond. • La-Cu-Al shows superior activity and stability for the pollutants removal. • More single electrons and octahedral Cu+ were responsible for more •OH generation. [ABSTRACT FROM AUTHOR]

In common advanced oxidation processes, excess reagents and energy are often added to the reaction system to maintain the continuity of the reaction. These additions result in a large waste of resources and energy, which has become a bottleneck in the development of water treatment technology. In this study, we propose a new strategy to solve this problem based on a novel dual-reaction-center (DRC) Fe-ZnS quantum dots (Fe–ZnS QDs) catalyst that forms a non-equilibrium surface with an electron-polarized distribution. Through experimental and theoretical studies, it was verified that the activation of trace amounts of H 2 O 2 could break the energy barrier for pollutants to transfer electrons. The dissolved oxygen (DO) in the reaction system could be activated by gaining energy on the surface of the Fe–ZnS QDs catalyst, and was converted to 1O 2 to attack organic pollution. In addition, the pollutants themselves supplied electrons to H 2 O 2 through the surface of the Fe–ZnS QDs catalyst to generate more •OH radicals for pollutant degradation, thus providing two fast paths for pollutant degradation. The system could drive the reaction through a trace amount of H 2 O 2 , thereby activating DO to generate 1O 2 while effectively using the energy of pollutants. Therefore, the proposed system offers a new direction for the development of environmentally-friendly catalysts and greatly reduces the consumption of resources and energy. [Display omitted] • Fe–ZnS QDs is successfully developed as a Fenton catalyst for the first time. • The surface of ZnS QDs is regulated by trace Fe to form a non-equilibrium surface with an electron-polarized distribution. • The Fe–ZnS QDs/H 2 O 2 system exhibits excellent activity for pollutants degradation. • Inert oxygen species in reaction system are easily activated to 1O 2 to attack pollutants. [ABSTRACT FROM AUTHOR]

Few-layered Bi 4 O 5 I 2 nanosheets (FL-Bi 4 O 5 I 2) were synthesized by intergrowth with Bi 2 O 2 CO 3 under room temperature. The photoactivity of FL-Bi 4 O 5 I 2 was 2.5 and 9.5 times higher than that of Bi 4 O 5 I 2 nanoflakes (NF-Bi 4 O 5 I 2 , about 30 nm thickness) and standard visible-light-driven N-TiO 2 , respectively. Moreover, FL-Bi 4 O 5 I 2 exhibited a wide pH application range (3.0 – 10.0) and excellent photostability. The characterization results showed FL-Bi 4 O 5 I 2 was consisted of 5 – 8 layers with thickness of 4 – 7 nm and enclosed by {1 0 − 1} facets. The ultrathin characteristics could accelerate the charge transfer to the surface due to the shortened transport distance. Compared to NF-Bi 4 O 5 I 2 , surface oxygen vacancies and the more negative CB potential were formed on FL-Bi 4 O 5 I 2. The photogenerated electrons were confirmed to be captured by surface oxygen vacancies to effectively reduce surface adsorbed O 2 into HO 2 •/O 2 •–, leaving more h+ to oxidize organic pollutants. This process was further facilitated by the more negative CB potential of FL-Bi 4 O 5 I 2 , resulting in the highly efficient removal of pollutants. [Display omitted] • Few-layered Bi 4 O 5 I 2 were formed by intergrowth with Bi 2 O 2 CO 3 at room temperature. • FL-Bi 4 O 5 I 2 was enclosed by {1 0−1} facets with surface oxygen vacancies. • Surface oxygen vacancies as electron traps promoted the efficient reduction of O 2. • HO 2 •/O 2 •– and holes were involved in the photocatalytic degradation process. • Organic pollutants were efficiently degraded by the surface adsorption and oxidation process. [ABSTRACT FROM AUTHOR]

Herein, a novel BiOBr photocatalyst with partial surface modification by graphitized C (BiOBr-C g) was synthesized through a hydrothermal method with hydrothermal carbonation carbon (HTCC) as a slow-releasing carbon source and characterized by experimental and theoretical methods. BiOBr-C g exhibited excellent visible-light photocatalytic performance toward various refractory pollutants, such as bisphenol A, ibuprofen, ciprofloxacin, 2,4-dichlorophenoxyacetic acid, and diphenhydramine. The characterization results demonstrate that a strong molecular orbital interaction occurs between graphitized C and BiOBr, resulting in the formation of a new surface valence band on graphitized C. This not only promotes the oxidation of pollutants by surface holes but also reduces the recombination of carriers during the bulk phase transfer process, thereby increasing the number of photogenerated carriers. Intriguingly, the analytical results for degradation intermediates and other characterization techniques demonstrate that the pollutants adsorbed on the graphitized C of BiOBr-C g can be directly excited through light irradiation and react along the organic radical degradation pathway in addition to pollutant degradation by holes and HO 2 •/O 2 •-. [Display omitted] • A novel BiOBr photocatalyst (BiOBr-C g) partly coated by graphitized C with HTCC as a slow-releasing carbon source. • The surface valence band derived from graphitized C reduces the recombination of e-/h+ during bulk phase transfer process. • The pollutant adsorbed on BiOBr-C g promotes direct transfer of excited electrons along organic radical degradation pathway. • Pollutant adsorption plays a role of molecular modification to facilitate the generation of more HO 2 •/O 2 •-. [ABSTRACT FROM AUTHOR]

A novel metal-free catalyst consisting of typical flower-like graphitized polyimide (g-PI) is first synthesized via an enhanced hydrothermal polymerization process, and it exhibits excellent performance for pollutant removal through peroxymonosulfate (PMS) activation over a wide pH range (3−11). The catalyst is especially effective for attacking the endocrine disruptor bisphenol A (BPA), which can be completely degraded in a short time. Based on the results of characterization, g-PI is consisted of abundant aromatic frameworks with π conjugates based on C-O-C linkages and N-hybrid rings, which play essential roles in the subsequent degradation of pollutants. In the g-PI/PMS/BPA system, BPA (rich in π bonds) is preferentially adsorbed to the catalyst surface through π-π interactions, accompanied by a decrease in its activation energy to produce surface-adsorbed BPA*. This species can be directly attacked and degraded by PMS without the need for the radical processes, which saves the energy required for the intermediate activation process of PMS. On the other hand, the electrons obtained from pollutants are rapidly transferred to the O center, driving PMS activation to generate free radicals. The synergetic interface process offers excellent potential for practical wastewater purification. [Display omitted] • g-PI is synthesized by graphitization of metal-free polyimide (PI). • g-PI/PMS system shows excellent activity in degrading organic pollutants. • Pollutants are preferentially adsorbed on the surface of g-PI through π-π interactions. • Surface-adsorbed species can be directly oxidized by PMS without the need for radical processes. [ABSTRACT FROM AUTHOR]

d-g-C 3 N 4 -Fe composites was prepared via a self-assembly and calcination process. According to measurements and density functional theory (DFT) computations, the complexation of iron and pyridinic N of g-C 3 N 4 (Fe‒N) occurred with Fe(III)-π interaction, causing more oxygen vacancies (OVs) with more electrons in iron oxides. In the catalyst air-saturated suspension, the adsorbed pollutants complexed surface Fe(III) through their hydroxyl group donated electrons to around OVs, reducing the surface Fe(III) to Fe(II) and were destructed by Fe(III)-π interaction of the complexation. The addition of H 2 O 2 mainly acted as acceptor being reduced •OH at the OV centers, causing higher degradation rate of pollutants due to both •OH and the surface reaction. However, for the adsorbed hydrophobic pollutants onto the sites of peripheral structure in g-C 3 N 4 , H 2 O 2 was mainly decomposed into O 2 by the synergistic effect of iron species and OVs. Therefore, the catalyst exhibited high Fenton-like efficiency for the degradation of hydroxyl-containing pollutants and hydrophobic pollutants mixing with the former. Our results demonstrate that the Fe(III)-π interaction could carry out the oxidation of pollutants on the catalyst surface, decreasing the consumption of H 2 O 2 , and the role of OVs depends on pollutant adsorption patterns. ga1 • Fe‒N complexation formed between g-C 3 N 4 and iron oxide in d-g-C 3 N 4 -Fe. • More oxygen vacancies produced in iron oxide of d-g-C 3 N 4 -Fe. • Degradation of organics was performed from the surface oxidation rather than •OH. • d-g-C 3 N 4 -Fe shows excellent activity for hydroxyl-containing pollutants degradation. • Efficiency of H 2 O 2 depended on the synergistic effect of OVs and pollutant adsorption. [ABSTRACT FROM AUTHOR]

• C and O dual-doped g-C 3 N 4 was generally synthesized via copolymerization. • C and O dual doping induces electronic structure reconfiguration in CN-AA 0.3. • CN-AA 0.3 exhibits good reactivity and stability in non-photochemical PMS activation. • Electron-poor C and electron-rich O atoms serve as active sites for PMS activation. • PMS activation over CN-AA 0.3 involves simultaneous PMS oxidation and reduction. Earth-abundant, environmental-benign and durable catalysts are of paramount importance for remediation of organic pollutants, and graphitic carbon nitride (g-C 3 N 4) is a promising nonmetallic material for this application. However, the catalytic oxidation on g-C 3 N 4 suffers from low efficiency because of its chemical inertness if not irradiated with light. Herein, we develop a facile copolymerization strategy for the synthesis of carbon and oxygen dual-doped g-C 3 N 4 using urea as g-C 3 N 4 precursor and ascorbic acid (AA) as carbon and oxygen sources, which induces electronic structure reconfiguration. By replacing AA with other organic precursors, a series of C and O dual-doped g-C 3 N 4 are successfully prepared, demonstrating the generality of the developed methodology. As a demonstration, the C and O dual-doped g-C 3 N 4 using AA as the organic precursor (CN-AA 0.3) exhibits pronouncedly enhanced catalytic activity in peroxymonosulfate (PMS) activation for organic pollutant degradation without light irradiation compared with pristine g-C 3 N 4 and single oxygen-doped g-C 3 N 4. Experimental and theoretical results revealed the electron-poor C atoms and electron-rich O atoms as active sites for PMS activation in terms of simultaneous PMS oxidation and reduction. This work offers a universal approach to synthesize nonmetal dual-doped g-C 3 N 4 with reconfigured electronic structure, stimulating the development of g-C 3 N 4 -based materials for diverse environmental applications. [ABSTRACT FROM AUTHOR]

• nZVCu-Cu(II)-rGO is developed via an annealing reduction process for first time. • Nanoscale Cu(0) and Cu(II) are generated on rGO along with C-O-Cu formation. • Dual reaction centers form around Cu(II) and aromatic rings of rGO due to π→Cu. • Nanoscale Cu(0) accelerate the electron transfer of the dual reaction center system. • Pollutants are efficiently degraded by two ways: as electron donors and attacked by radicals. Nanoscale zero-valent copper combined with Cu(II)-doped reduced graphene oxide hybrid (nZVC-Cu(II)-rGO) is synthesized through an annealing reduction process, and it shows very high activity and efficiency for removing refractory organic compounds with H 2 O 2. The conversion rate for the organic pollutant in this system is ∼77 and ∼13 times higher than that in the graphene oxide (GO) and reduced graphene oxide (rGO) systems, respectively. The characterization shows that nanoscale Cu(0) and Cu(II) are generated on the rGO surface during the annealing process and they are accompanied by the C O Cu bonding formation between the rGO substrate and the Cu(II) species in nZVC-Cu(II)-rGO, which induces cation–π interactions on the surface, resulting in the reinforced electron-rich micro-centers formation around the nZVC-enhanced Cu(II) species and electron-poor micro-centers on rGO-aromatic rings. The generation of nanoscale Cu(0) consolidates the polarization of the dual reaction micro-centers and greatly accelerates the electron transfer of the system, thus promoting H 2 O 2 reduction to OH in the electron-rich micro-centers. Pollutants can obviously replace H 2 O 2 as the electron donors of the system and are efficiently oxidized and degraded in the electron-poor micro-centers, with their own electron energy being fully utilized in the nZVC-Cu(II)-rGO Fenton-like system. [ABSTRACT FROM AUTHOR]