查看更多>>摘要：The research of highly efficient and large-capacity energy storage systems is the focus of the research community and the market. Lithium-oxygen (Li-O2) batteries have shown great potential as next generation secondary batteries since their energy density is comparable to that of gasoline. Herein, we report a three dimensional (3D) self-supporting Co-CoSe@NSeC/bioC cathode fabricated through growing cobalt based metal organic framework (ZIF-67) on biomass and subsequent high-temperature selenization. The as synthesized Co-CoSe@NSeC/bioC cathode, benefiting from the 3D porous structure, the active defects derived from the doping of N, Se heteroatoms in carbon skeleton, and the highly-active of Co/CoSe heterojunction, shows excellent oxygen reduction reaction/oxygen evolution reaction (ORR/OER) electrocatalytic activity. It delivers a high specific capacity of 9.1 mAh · cm~(-2) at a current density of 0.05 mA · cm~(-2) and maintains 78 stable cycles. The good performance of Co-CoSe@NSeC/bioC proves its potential as cathode for Li-O2 batteries.
查看更多>>摘要：In this work, an atomic-layer Fe2O3-moclified two -dimensional (2D) porphyrinic metal-organic framework (MOF) was prepared (2D MOF-Fe2O3), which exhibits unique interfacial electron-withdrawing effect via charge transfer pathways from Zn2O3 and C-O bonds to Fe-O bonds. Concretely, the atomic-layer Fe2O3 is deposited on 2D porphyrinic MOF (ZnTCPP) by atomic layer deposition technique to enhance the photocatalytic performance and the subsequent bacteria-killing efficacy. After 20 min light irradiation, the photocatalytic antibacterial efficacy of 2D MOF-Fe2O3 can reach up to 99.9%. The underlying mechanism of enhanced photocatalytic activity is that the heterointerface between 2D MOF and Fe2O3 can facilitate the transfer of lots of photogenerated electrons from 2D MOF to Fe2O3, where 2D MOF and Fe2O3 act as electronic donator and receptor, respectively. This work provides an insight into developing highly effective photocatalysts by using electron-withdrawing modulator to optimize charge transfer pathway.
查看更多>>摘要：Ultrafine cuprous oxide U-Cu2O (< 3 nm) was obtained via in situ reduction of Cu-based layered trimetal hydroxide on the polymeric carbon nitride (PCN). This facilely synthetic strategy with confinement effect results in a series of Z-scheme heterostructures U-Cu2O-LTH@PCN-X (X = 1, 2, 3,4, 6 and 15) via loading different amounts of PCN, which can promote CO2 photoreduction in water vapor with excellent stability. The CH3OH yield can reach to 440.78 μmol g~(-1), much superior to that of most Cu2O-based photocatalysts. Systematic investigations demonstrate that ultrafine nanoclusters and Z-scheme heterojunction can accelerate photogenerated carrier separation and extract holes to mitigate the degradation of U-Cu2O in U-Cu2O-LTH@PCN. The resulting U-Cu2O-LTH@PCN only presents < 4% loss of the activity after 5 recycle experiments, whereas bare Cu2O degrades completely within three cycles. This work supplies a new insight to improve the stability of U-Cu2O via extracting holes to achieve high-performance CO2 photoreduction.
查看更多>>摘要：Complex tunable visible-light-driven Aurivillius-phase-based micro- and nanostructured photocatalysts were fabricated following a novel, scalable, easily implemented sequential process based on electrochemical deposition and thermal treatment. Regarding its novelty, electrochemistry was the primary tool for synthesis, one that constitutes a viable alternative to other complex chemical and physical processes. The parameters of electrodeposition and thermal conditions promoted different nanostructured Bi2MoO6 and Bi2MoO6@Bi2MoO_(6-x) films. The nano structured homojunction Bi2MoO6@Bi2MoO_(6-x) films obtained after 3 h of calcination showing micro- and nanowire morphology emerged as the most effective photocatalyst for degrading and mineralizing the mono- and multiantibiotic solutions (i.e., tetracycline, ciprofloxacin, and/or levofloxacin), which achieved near-total degradation and exceptionally high mineralization values (>95%) after 180 min of radiation. The materials' proven reusability, low photo corrosion activity, and excellent photocatalytic performance in mineralizing antibiotics can support the implementation of Bi2MoO6@Bi2MoO_(6-x) homojunctions as efficient visible -light photocatalysts under solar radiation.
查看更多>>摘要：This work investigated the triggering mechanism of peroxymonosulfate (PMS) activated by an oxygen vacancy (Ov)-rich cobalt (Co)-based hydrotalcite-like compound (CA-LDH). CA-LDH was synthesized by a urea-hydrothermal process with ammonium citrate (CA) as the reducing agent. The PMS activation mechanism was investigated by combining batch experiments, characterization techniques, and DFT calculations. Over 98 % of CIP (20 mg/L) was degraded by the CA-LDH/PMS system within 60 min, which remained efficient in the presence of common interfering substances or over a wide pH range. DFT showed that CA was beneficial for introducing the electron transfer intermediate, namely, Ov, on CA-LDH, thereby allowing for the unique electron transfer performance of CA-LDH. Specifically, electron transfer from Co-Ov to PMS triggered the radical pathway, while electron transfer from PMS to Co-Ov triggered the nonradical pathway. Overall, this study provides a reference for the rational catalyst synthesis and the investigation of the triggering mechanism of PMS activation.
Stefano CiminoElisabetta Maria CepollaroLuciana Lisi
9页
查看更多>>摘要：The combined CO2 capture and methanation with Dual Function Materials (DFM) is emerging as a vibrant field of research for its potential to increase the efficiency and reduce the cost of current multistage CCU processes. In this work, we set out to investigate for the first time the impact of sulfur poisoning over a Na-Ru/Al2O3 DFM operated in a fixed bed reactor with alternate feeds under realistic conditions including the presence of SO2, H2O and O2 in the process gas stream. The results of the extensive characterization of the fresh and sulfated (reaction-aged) DFM evidenced a remarkable intrinsic tolerance of the combined CO2 capture and methanation process to high concentrations of SO2 in the feed due to a self-regeneration mechanism of the Ru catalytic sites.
查看更多>>摘要：The metal-ligand (M-L) covalent coupling is of very significance for tailoring the activity and selectivity of metal-organic-framework (MOF) functional nanomaterials, yet it still remains elusive. Herein, based on the π-conjugated coordination chemistry, we have developed several conductive MOFs as active oxygen reduction (ORR) electro catalysts with tunable H2O2 selectivity. Through tailoring the central metal and the first coordination sphere, weakly-electrophilic Cu sites coupled with strongly-oxidized aromatic 2, 3, 6, 7,10,11-hexahydroxytriphenylene (HHTP) linkers are of high favor in a two-electron ORR pathway, resulting in an impressive H2O2 selectivity of 95 % and a superior H2O2 yield rate of 792.7 mmol · g_(cat)~(-1) · h~(-1) during ORR for conductive Cu-HHTP MOF catalysts. By correlative in situ synchrotron radiation XAFS and FTIR spectroscopies, the potential-dependent dynamic-coupling hydroxyl over Cu sites is found to effectively trigger the self-polarization of n-conjugated metal-ligand Cu-O-C centers of Cu-HHTP MOF via shrinking the first Cu-O coordination sphere, realizing fast 2e~- ORR kinetics.
查看更多>>摘要：Photochemical dehydrogenation of N-heterocyclic amines to corresponding N-heteroaromatics paired with hydrogen (H2) production represents a promising route for the green and sustainable organic synthesis and clean fuel generation. Herein, metal-organic frameworks (MOFs)-supported CdS nanoparticles are gingerly fabricated for the visible light-initiated acceptorless dehydrogenation of diverse N-heterocycles at ambient conditions. With further nickel cocatalysts modification via a simple photodeposition method, the optimized MIL-101 @CdS-Ni composite exhibits remarkably enhanced activities, which are 8 folds higher than that of binary MIL-101 @CdS and 2.8 times higher than that of MOF-removed CdS-Ni counterparts, along with high selectivity and good stability. Mechanism studies reveal that active nickel species plays a key role in accelerating the separation of photogenerated charge carries and the cleavage of C-H and N-H bonds in the scaffold of N-heterocycles on the catalyst surface. This work is expected to guide the rational catalysts design of MOF-based multifunctional materials for photochemical coupling of concurrent organic synthesis with H2 production.
查看更多>>摘要：Ribavirin (RBV) is an antiviral drug used for treating COVID-19 infection. Its release into natural waters would threaten the health of aquatic ecosystem. This study reports an effective approach to degrade RBV by the trace N-oxyl compounds (2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and N-Hydroxyphthalimide (NHPI)) enhanced UV activated free chlorine (UV/Chlorine) process. The results indicated that TEMPO and NHPI at low concentrations (0.1 μM and 1 μM, respectively) could strongly enhance RBV degradation in both deionized water with different pHs and practical surface water. The enhancement was verified to be attributed to the transformation of TEMPO and NHPI into their reactive forms (i.e., TEMPO~+ and PINO), which generations deeply relied on radicals. The two N-oxyl compounds inhibit ClO~· yield by hindering the reaction of free chlorine vs. HO· and Cl·. The analyses on acute toxicities of RBV degradation products indicate that UV/Chlorine/N-oxyl compounds process can detoxify RBV more efficiently than UV/Chlorine process.
查看更多>>摘要：Covalent organic frameworks (COFs) are an emerging type of visible-light-driven photocatalysts, yet the introduction of Pt cocatalyst is inevitable to achieve an efficient activity in most COF-based photocatalysts. Herein, we report a multifunctional MOF/COF heterostructured photocatalyst, Cu-NH2-MIL-125/TpPa-2-COF, with Cu ions immobilized by -NH2 groups of MOF, where the covalently connected heterojunction facilitates the separation of photogenerated charges and the monodispersed transient Cu~(2+)/Cu~+ centers serve as effective active sits. The resultant Cu-NH2-MIL-125/TpPa-2-COF (4:6) exhibits a visible-light-driven photocatalytic H2 evolution rate of 9.21 mmol · g~(-1) - h~(-1), which is 7.3 and 17.7 times higher than that without Cu coordination and the pristine TpPa-2-COF, respectively, and superior to various reported COF and MOF-based photocatalysts without Pt. Moreover, the photocatalyst can efficiently oxidate amines to imines with high conversion rate (91.2 %) and selectivity (>99 %). The crucial role of Cu centers as active sites and its stability in long-term reaction was determined.
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