The direct functionalization of inert C(sp3)−H bonds under environmentally benign catalytic conditions remains a challenging task in synthetic chemistry. Here, we report an organocatalytic remote ...C(sp3)−H acylation of amides and cascade cyclization through a radical‐mediated 1,5‐hydrogen atom transfer mechanism using N‐heterocyclic carbene as the catalyst. Notably, a diversity of nitrogen‐containing substrates, including simple linear aliphatic carbamates and ortho‐alkyl benzamides, can be successfully applied to this organocatalytic system. With the established protocol, over 120 examples of functionalized δ‐amino ketones and isoquinolinones with diverse substituents were easily synthesized in up to 99 % yield under mild conditions. The robustness and generality of the organocatalytic strategy were further highlighted by the successful acylation of unactivated C(sp3)−H bonds and late‐stage modification of pharmaceutical molecules. Then, the asymmetric control of the radical reaction was attempted and proven feasible by using a newly designed chiral thiazolium catalyst, and moderate enantioselectivity was obtained at the current stage. Preliminary mechanistic investigations including several control reactions, KIE experiments, and computational studies shed light on the organocatalytic radical reaction mechanism.
An N‐heterocyclic carbene catalyzed remote C(sp3)−H acylation of amides was developed, and also combined with a cascade cyclization. Over 120 functionalized δ‐amino ketones and isoquinolinones with diverse substituents were synthesized in up to 99 % yield under mild conditions. Preliminary mechanistic investigations shed light on the organocatalytic radical reaction mechanism.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Transition‐metal oxides as electrocatalysts for the oxygen evolution reaction (OER) provide a promising route to face the energy and environmental crisis issues. Although palmeirite oxide A2Mo3O8 as ...OER catalyst has been explored, the correlation between its active sites (tetrahedral or octahedral) and OER performance has been elusive. Now, magnetic Co2Mo3O8@NC‐800 composed of highly crystallized Co2Mo3O8 nanosheets and ultrathin N‐rich carbon layer is shown to be an efficient OER catalyst. The catalyst exhibits favorable performance with an overpotential of 331 mV@10 mA cm−2 and 422 mV@40 mA cm−2, and a full water‐splitting electrolyzer with it as anode catalyst shows a cell voltage of 1.67 V@10 mA cm−2 in alkaline. Combined HAADFSTEM, magnetic, and computational results show that factors influencing the OER performance can be attributed to the tetrahedral Co sites (high spin, t23e4), which improve the OER kinetics of rate‐determining step to form *OOH.
Magnetic Co2Mo3O8@NC‐800 composed of single‐crystal Co2Mo3O8 and ultrathin nitrogen‐rich carbon was synthesized to uncover its OER active sites (Td Co2+ or Oh Co2+). Electrochemical data, magnetism data, and computations suggest that the Td Co2+ atoms (high spin, t23e4) in Co2Mo3O8 act as active sites facilitating the rate‐determining step, forming *OOH to promote the reaction kinetics for OER.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In order to deal with cadmium (Cd(II)) pollution, three modified biochar materials: alkaline treatment of biochar (BC-NaOH), KMnO4 impregnation of biochar (BC-MnOx) and FeCl3 magnetic treatment of ...biochar (BC-FeOx), were investigated. Nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), Boehm titration, and scanning electron microscopy (SEM) were used to determine the characteristics of adsorbents and explore the main adsorption mechanism. The results show that manganese oxide particles are carried successfully within the biochar, contributing to micropore creation, boosting specific surface area and forming innersphere complexes with oxygen-containing groups, while also increasing the number of oxygen-containing groups. The adsorption sites created by the loaded manganese oxide, rather than specific surface areas, play the most important roles in cadmium adsorption. Batch adsorption experiments demonstrate a Langmuir model fit for Cd(II), and BC-MnOx provided the highest sorption capacity (81.10 mg g−1). The sorption kinetics of Cd(II) on adsorbents follows pseudo-second-order kinetics and the adsorption rate of the BC-MnOx material was the highest (14.46 g (mg·h)−1). Therefore, biochar modification methods involving KMnO4 impregnation may provide effective ways of enhancing Cd(II) removal from aqueous solutions.
•NaOH-treated, MnOx-loaded, and magnetic biochars were compared for Cd(II) sorption.•MnOx-biochar composite showed the highest sorption capacity for Cd(II) in solution.•MnOx-loaded biochar composite markedly changed surface areas and pore volumes.•Oxygen-containing groups were noticeably increased in MnOx-biochar composite.•Cation-exchange and cation-π bonding are main mechanisms in MnOx-biochar composite.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Herein, we demonstrate the use of heterostructures comprised of Co/β‐Mo2C@N‐CNT hybrids for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline electrolyte. The ...Co can not only create a well‐defined heterointerface with β‐Mo2C but also overcomes the poor OER activity of β‐Mo2C, thus leading to enhanced electrocatalytic activity for HER and OER. DFT calculations further proved that cooperation between the N‐CNTs, Co, and β‐Mo2C results in lower energy barriers of intermediates and thus greatly enhances the HER and OER performance. This study not only provides a simple strategy for the construction of heterostructures with nonprecious metals, but also provides in‐depth insight into the HER and OER mechanism in alkaline solution.
That's evolution: Heterostructures composed of Co/β‐Mo2C@N‐CNTs showed high performance for HER and OER in an alkaline electrolyte. The Co nanoparticles not only create a well‐defined heterointerface with β‐Mo2C, but also overcome the poor OER activity of β‐Mo2C, thus leading to enhanced electrocatalytic activity for HER and OER. DFT calculations showed that cooperation by the N‐CNTs, Co, and β‐Mo2C lowers the energy barriers of intermediates.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The interaction mechanism between the reacting species and the active site of α‐Fe2O3‐based photoanodes in photoelectrochemical methanol conversion reaction is still ambiguous. Herein, a simple ...two‐step strategy is demonstrated to fabricate a porous α‐Fe2O3/CoFe2O4 heterojunction for the methanol conversion reaction. The influence of the electronic structure of active site and interfacial effect on the reaction are investigated by constructing two different FeO6 octahedral configurations and heterogeneous structures. The optimal sample ZnFeCo‐2 affords high photocurrent density of 1.17 mA cm−2 at 0.5 V vs Ag/AgCl, which is 3.2 times than that of ZnFe (0.37 mA cm−2). Meanwhile, the ZnFeCo‐2 also exhibits 97.8% Faraday efficiency of CH3OH to HCHO, and long‐term stability over 40 h. Furthermore, density functional theory calculations reveal that the heterostructured α‐Fe2O3/CoFe2O4 with favorable electron transfer effectively lowers methanol adsorption, C–H bond activation, and HCHO desorption energy relative to the pristine α‐Fe2O3, resulting in excellent methanol conversion efficiency.
A spinel‐CoFe2O4‐decorated α‐Fe2O3 nanotube arrays (NTAs) photoanode is developed for the oxidation of methanol to formaldehyde. The superiority of the co‐edged FeO6 octahedral structure in the Formox process is demonstrated. Impressively, the heterostructure and the interfacial effect of α‐Fe2O3 and CoFe2O4 facilitates the separation and transport of photogenerated carriers, resulting in superior PEC methanol conversion efficiency and formaldehyde selectivity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The highly active and stable oxygen evolution reaction (OER) performance of Ni-Fe phosphide/metaphosphate (Ni
1−
x
Fe
x
-P/PO
3
) can originate from
in situ
generated Fe doped γ-NiOOH. The optimized ...Ni
0.75
Fe
0.25
-P/PO
3
@fCNT catalyst exhibits excellent activity and stability with an overpotential of 239 mV at 10 mA cm
−2
and a negligible decrease after 200 h continuous electrolysis in an alkaline solution.
The highly active and stable oxygen evolution reaction (OER) performance of Ni-Fe phosphide/metaphosphate (Ni
1−
x
Fe
x
-P/PO
3
) can originate from
in situ
generated Fe doped γ-NiOOH.
Reinforced concrete structures exposed to marine environments often experience chloride ingress, reinforcement corrosion, and corrosion‐induced cracking. The electrochemical repair method is a ...promising concrete rehabilitation technique with advantages of non‐destructive and economic performance in crack repair, chloride removal, and corrosion protection, which is particularly suitable for structures exposed to marine environments. This work presents an innovative methodology for modeling the mechanical, transport, and chemical process during electrochemical treatment for marine concrete structures. The entire process from concrete cracking up to repairing can be successfully reproduced and digitally visualized. The first sub‐model calculates the corrosion‐induced cracking process at the mesoscopic level with the consideration of local mechanical variances of concrete composites. Then, a reactive transport sub‐model is established to reveal the interactions and electrochemical reactions among various species of ions. A crack repair sub‐model is built to visualize the moving interface between chemical deposition and crack surface. Through combining the three sub‐models, the interconnected influencing factors in practical engineering can be quantitively investigated. The calculation results show that, compared with electrolyte concentration, the influence of current density on crack closure rates are more obvious. Other factors such as steel reinforcement diameter and crack distribution pattern, which have not been previously reported are highlighted. These findings can guide the application of electrochemical repair in practical engineering.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Although the synthesis of single atom catalysts (SACs) has attracted intensive attention for the hydrogen evolution reaction (HER), realizing the precise control of the structure of atomic catalysts ...and the electronic metal–support interaction is still highly challenging. The understanding of SACs at the atomic level is particularly important for further improving their electrochemical performances. Herein, we have reported the synthesis of a spinel Mn3O4 supported Pt SAC (PtSA–Mn3O4) based on the in situ precise anchoring of the Pt atoms in the octahedral sites for the first time. The strong interactions between Pt and Mn3O4 have significantly modulated the electronic structures with an optimized d-band center and binding strength of intermediates. In an alkaline environment, the catalyst shows an excellent HER performance with an ultra-low overpotential of 24 mV at 10 mA cm−2 and a high mass activity of 374 mA mg−1Pt (50 mV), which are superior to those of 20 wt% Pt/C and the most reported high-performance catalysts. This work has supplied insightful information for the rational design of efficient SACs with high controllability and superior performances.
The large‐scale production of metal–air batteries, an appealing solution for next‐generation energy storage, requires low‐cost, earth‐abundant, and efficient oxygen electrode materials, yet insights ...into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen‐doped carbon nanotubes decorated by spinel CuCo2O4 quantum dots (CuCo2O4/N‐CNTs) is reported, outperforming the benchmark of state‐of‐the‐art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo2O4 and N‐doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu2+ and CuN) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo2O4/N‐CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all‐solid‐state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm−2 in liquid state, 1.86 W g−1 in all‐solid‐state), and long lifetime (48 h in liquid state, 9 h in all‐solid‐state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells.
Advanced Cu Co bimetallic oxide quantum dots are decorated on nitrogen‐doped carbon nanotubes to serve as the bifunctional oxygen catalyst. A strong synergetic coupling in CuCo2O4/N‐CNTs is proposed, which provides advantaged local chemical environment and enriched catalytic sites. Benefiting from these features, CuCo2O4/N‐CNTs with reversible oxygen catalytic activity is capable of operating the new‐generation rechargeable zinc–air batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Bimetallic cobalt‐based spinel is sparking much interest, most notably for its excellent bifunctional performance. However, the effect of Fe3+ doping in Co3O4 spinel remains poorly understood, mainly ...because the surface state of a catalyst is difficult to characterize. Herein, a bifunctional oxygen electrode composed of spinel Co2FeO4/(Co0.72Fe0.28)Td(Co1.28Fe0.72)OctO4 nanoparticles grown on N‐doped carbon nanotubes (NCNTs) is designed, which exhibits superior performance to state‐of‐the‐art noble metal catalysts. Theoretical calculations and magnetic measurements reveal that the introduction of Fe3+ ions into the Co3O4 network causes delocalization of the Co 3d electrons and spin‐state transition. Fe3+ ions can effectively activate adjacent Co3+ ions under the action of both spin and charge effect, resulting in the enhanced intrinsic oxygen catalytic activity of the hybrid spinel Co2FeO4. This work provides not only a promising bifunctional electrode for zinc–air batteries, but also offers a new insight to understand the Co‐Fe spinel oxides for oxygen electrocatalysis.
A bifunctional oxygen electrode composed of hybrid spinel Co2FeO4 nanoparticles grown on N‐doped carbon nanotubes is a promising candidate for zinc–air batteries. Theoretical calculations and magnetic measurements reveal that the introduction of Fe cations into the Co3O4 network causes Co 3d electron delocalization and spin‐state transition, resulting in enhanced catalytic activity of the as‐prepared spinel Co2FeO4.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
