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Constructing heterostructures is an efficient strategy to develop high‐performance and robust electrocatalysts for oxygen evolution reaction (OER). Herein, an ion‐impregnation method and an environmentally friendly in situ carbonization strategy are successively employed to fabricate a novel Co3Mo/Mo2C heterostructure anchored on nitrogen‐doped carbon (Co3Mo/Mo2C@NC). Thanks to the formation of heterostructure, the obtained Co3Mo/Mo2C@NC exhibits an enhanced catalytic performance toward OER with a low overpotential (282 mV @ 10 mA cm−2, 322 mV @ 50 mA cm−2, and 355 mV @100 mA cm−2) and robust stability (100 mA cm−2 for 200 h) in alkaline media. Detailed experimental results combined with theoretical calculations reveal the formation of a Co3Mo/Mo2C heterojunction interface can decrease the energy barrier of the rate‐determining step for intermediates during the OER process, thereby inherently enhancing the OER performance. This work presents a rational synthetic route for designing high‐performance heterostructures for energy conversion technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] Rational design of novel conjugated step-scheme (S-scheme) multijunction heterostructure with synergistic charge channelization, superior light harvesting efficiency and strong redox ability is a pioneering approach to mimic natural photosynthesis process. Herein, a mild cetyltrimethyl ammoniumbromide (CTAB) assisted one pot reflux synthesis route is designed for in situ integration of metal organic framework (MOF)-derived NiFe 2 O 4 with tetragonal-BiVO 4 (t-BiVO 4) and γ-Bi 2 MoO 6 to prepare NiFe 2 O 4 /t-BiVO 4 /Bi 2 MoO 6 (NFO/BVO/BMO) ternary composites. Morphologically, fine dispersion of NiFe 2 O 4 (NFO) quantum dots over γ-Bi 2 MoO 6 (BMO) and t-BiVO 4 (BVO) nanoplates yielded three types of microscopic heterojunctions among BMO-BVO, BVO-NFO and BMO-NFO phases. The ternary composites displayed important physicochemical attributes including high surface area, strong optical absorption, superior charge mobility and higher excited state lifetime which accounted for its improved photocatalytic activity towards ciprofloxacin degradation (>99% in 90 min) and H 2 evolution (1.11 mmolh-1g−1, photon conversion efficiency 18.5%). Kinetics study revealed 12–55 fold higher ciprofloxacin photodegradation activity and 31–41 times higher H 2 evolution rate for the ternary composite in comparison to the pure semiconductors. A conjugated S-scheme charge transfer mechanism has been deduced from comprehensive band position analysis and radical trapping study to explain the enhanced photocatalytic activity. This work for the first time demonstrated the rational construction of conjugated S-scheme heterostructures with potential application in water remediation and green H 2 production. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) have unique properties and stable structures, which have been widely used as templates/precursors to prepare well developed pore structure and high specific surface area materials. In this article, an innovative and facile method of crystal reorganization was designed by using MOFs as sacrificial templates to prepare a layered double hydroxide (LDH) nano-layer sheet structure through a pseudomorphic conversion process under alkaline conditions. The obtained CoMn-LDH and CoFe-LDH catalysts broke the ligand of MOFs and reorganized the structure on the basis of retaining a high specific surface area and a large number of pores, which had higher specific surface area and well developed pore structure compared with LDH catalysts prepared by traditional methods, and thus provide more active sites to activate peroxymonosulfate (PMS). Due to the unique framework structure of MOFs, the MOF-derived CoMn-LDH and CoFe-LDH catalysts could provide more active sites to activate PMS, and achieve a 2,4-dichlorophenol degradation of 99.3% and 99.2% within 20 minutes, respectively. In addition the two LDH catalysts displayed excellent degradation performance for bisphenol A, ciprofloxacin and 2,4-dichlorophenoxyacetic acid (2,4-D). X-ray photoelectron spectroscopy indicated that the valence state transformation of metal elements participated in PMS activation. Electron paramagnetic resonance manifested that sulfate radical () and singlet oxygen (1O2) were the main species for degrading pollutants. In addition, after the three-cycle experiment, the CoMn-LDH and CoFe-LDH catalysts also showed long-term stability with a slight activity decrease in the third cycle. The phytotoxicity assessment determined by the germination of mung beans proved that PMS activation by MOF-derived LDH catalysts can basically eliminate the phytotoxicity of a 2,4-D solution. This research not only developed high-activity LDH catalysts for PMS activation, but also expanded the environmental applications of MOF derivants. HIGHLIGHTS LDH derived from MOFs through a pseudomorphic conversion process.; LDH showed excellent activity to activate PMS to degrade 2,4-DCP and other pollutants.; CoMn-LDH and CoFe-LDH exhibited high stability and reusability.; High specific surface area and well developed pore structure of LDH provide more active sites.; Phytotoxicity assessment displayed the practical application value of LDH.;

A series of hierarchical α-Bi 2 O 3 -BiVO 4 -CuFe 2 O 4 multijunction heterostructure was designed by integrating one-pot MOF derived Bi 2 O 3 -BiVO 4 microrods with CuFe 2 O 4 nanosheets. The MOF-derived route afforded Bi 2 O 3 -BiVO 4 with interconnecting porous architecture. Comprehensive investigations revealed preservation of crystalline phases, optimal light harvesting ability, higher lifetime, large electrochemically active surface area and improved charge dynamics. The heterostructure efficiently performed the photo-degradation of potentially toxic and mutagenic mesotrione (MTE) herbicide with rates 6–12 times greater than the parent semiconductors. The photo-degraded end products displayed profoundly less acute toxicity, bioaccumulation factor and mutagenic nature than parent MTE as analyzed by QSAR protocol. The heterostructure was equally effective for complete photo-inactivation of E. coli bacteria within 60 min of irradiation. SEM, AFM height profile and confocal microscopic investigation provided crucial information about the photo-inactivation process. A conjugated S-scheme electron transfer mechanism was proposed based on detailed band structure analysis to elucidate the improved activity of the multijunction photocatalyst. [Display omitted] • A hierarchical α-Bi 2 O 3 -BiVO 4 -CuFe 2 O 4 multijunction heterostructure fabricated through MOF derived route. • Distinct topology consisting of CuFe 2 O 4 nanosheets grafted over α-Bi 2 O 3 -BiVO 4 rods with interconnecting porous architecture. • Efficient photocatalytic mineralization of mesotrione herbicide with substantial reduction in acute and ecotoxicity. • Complete photo-inactivation of E. coli bacteria achieved within 60 min of irradiation. • A conjugated S-scheme charge transfer mechanism explains the improved photocatalytic activity. [ABSTRACT FROM AUTHOR]

Achieving selective detection of ppb-level CO is important for air quality testing at industrial sites to ensure personal safety. Noble metal doping enhances charge transfer, which in turn reduces the detection limit of metal oxide gas sensors. In this work, metal-organic framework-derived Au-doped In 2 O 3 nanotubes with high electrical conductivity are synthesized by pyrolysis of the Au-doped metal-organic framework (In-MIL-68) as a template. Gas-sensing experiments reveal that the detection limit of 0.2% Au-doped In 2 O 3 nanotubes (0.2% Au, mass fraction) is as low as 750 ppb. Meanwhile, the sensing material shows a response value of 18.2 to 50 ppm of CO at 240 °C, which is about 2.8 times higher than that of pure In 2 O 3 . Meanwhile, the response and recovery times are short (37 s/86 s). The gas-sensing mechanism of CO is uncovered by in situ DRIFTS through the reaction intermediates. In addition, first-principles calculations suggest that Au doping of In 2 O 3 significantly enhances its adsorption energy for CO and improves the electron transfer properties. This study reveals a novel synthesis pathway for Au-doped In 2 O 3 nanotubular structures and their potential application in low concentration CO detection.

• Rose flower-like NiCo-LDH (RF-NiCo-LDH) is prepared derivating from NiCo-MOFs. • The 3D rough flower-like structure and synergy effect are beneficial to catalysis. • RF-NiCo-LDH shows high sensing performance for N 2 H 4 detection. • RF-NiCo-LDH operates efficiently in food samples (prawns, kelp, beer and soda). It is necessary to efficient detection hydrazine in food. Exploring highly sensitive, low-cost and fast response electrochemical hydrazine sensing methods has been a challenge in this field. In this paper, a conformal transformation method is used to prepare rose flower-like NiCo-LDH derivating from the bimetallic NiCo-MOFs, and the N 2 H 4 sensing platform with a large electrocatalytic area, high conductivity and good stability was constructed. Based on the synergy between Ni and Co and the remarkable catalytic activity of the rough 3D flower-like structure, the N 2 H 4 sensor has a linear response in the concentration range of 0.001–1 mmol/L and 1–7 mmol/L, with a sensitivity of 5342 μA L mmol−1 cm−2 and 2965 μA L mmol−1 cm−2 (S/N = 3), respectively, and low limit of detection of 0.043 μmol/L. This study opens a new door for the successful application of electrochemical sensors to detect N 2 H 4 in real food samples. [ABSTRACT FROM AUTHOR]

The magnetic response behavior of microwave absorbing materials (MAMs) is beneficial to the expansion of the effective bandwidth in the high-frequency electromagnetic fields. However, the high density of magnetic components does not match with the lightweight requirement of MAMs. In response to this contradiction, the metal-organic framework (MOF) ZIF-67 material and melamine foam were used in the present work as the magnetic component and self-sacrificial template, respectively. A three-dimensional honeycomb carbon foam with zero-dimensional magnetic Co quantum dots (Co-QDs/CF) was prepared by a simple two-step method. The unique honeycomb structure significantly improved impedance matching and carrier mobility, providing more scattering paths for the electromagnetic wave conduction while reducing the overall density. In turn, the uniformly embedded magnetic Co-QDs endowed the 3D carbon foam with excellent high-frequency magnetic response while ensuring light weight. The ultra-small size (<10 nm) enhanced the exchange coupling between magnetic particles while suppressing the eddy current effect, and the magnetic loss capability was greatly improved. Interestingly, Co-QDs acting as numerous micro-resistors formed a large three-dimensional conductive network with the carbon skeleton, which demonstrated outstanding electron transport ability, so that the conductance loss was significantly enhanced. Surprisingly, the effective absorption bandwidth of Co-QDs/CF in the 2–18 GHz band was as high as 8.74 GHz with a matching thickness of 2.5 mm, while the corresponding filling rate was only 20 wt%. Thus, the proposed ingenious strategy to construct three-dimensional conductive networks using ultra-small magnetic quantum dots opens up new prospects for the development of lightweight broadband MAMs. [Display omitted] • Uniformly dispersed magnetic Co quantum dots were prepared. • The prepared magnetic carbon foam has a typical honeycomb structure. • Co-QDs/CF has ultra-clear characteristics and can be easily carried by cherry blossoms. • The best sample has an effective bandwidth of up to 8.74 GHz. [ABSTRACT FROM AUTHOR]

Co@C core-shell particles with a uniform size of approximately 100 nm anchored on rGO nano sheets is synthesized by a one-pot hydrothermal process. The Co@C particle formation is realized with a self-assembly procedure of metal-organic framework (MOF), and with GO as the precursor of rGO, Co@C/rGO is achieved. After calcination, the synthesized Co@C/rGO with high crystallization is obtained. Fabricated as an electrode by electrophoretic deposition, the calcined Co@C/rGO is evaluated with a high specific capacity of 810 C g−1 at a current density of 1 A g−1. With the calcined Co@C/rGO served as positive electrode and with as-prepared 3D rGO aerogel as negative electrode, an assembled asymmetric supercapattery possesses a wide operating potential window of 1.2 V. The specific capacitance of the supercapattery can be as high as 120 F g−1 at 0.6 A g−1, while the energy density reaches 29.5 W h kg−1 at a power density of 720 W kg−1, and 11.2 W h kg−1 at 12,000 W kg−1. After 10,000 cycles of charge-discharge process at 5 A g−1, the asymmetric supercapattery device shows considerable cyclic stability with capacitance retention of 93.7%. [Display omitted] • Co@C/rGO hybrid composite is synthesized with specific capacity of 810 C g−1. • The fabricated supercapattery possesses energy density of 11.2 W h kg−1 at 12,000 W kg−1. • The supercapattery has more activated property with a capacity retention of 93.7% after 10,000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]