Abstract
The discovery of moiré superlattices (MSLs) opened an era in the research of ‘twistronics’. Engineering MSLs and realizing unique emergent properties are key challenges. Herein, we ...demonstrate an effective synthetic strategy to fabricate MSLs based on mechanical flexibility of WS
2
nanobelts by a facile one-step hydrothermal method. Unlike previous MSLs typically created through stacking monolayers together with complicated method, WS
2
MSLs reported here could be obtained directly during synthesis of nanobelts driven by the mechanical instability. Emergent properties are found including superior conductivity, special superaerophobicity and superhydrophilicity, and strongly enhanced electro-catalytic activity when we apply ‘twistronics’ to the field of catalytic hydrogen production. Theoretical calculations show that such excellent catalytic performance could be attributed to a closer to thermoneutral hydrogen adsorption free energy value of twisted bilayers active sites. Our findings provide an exciting opportunity to design advanced WS
2
catalysts through moiré superlattice engineering based on mechanical flexibility.
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•The Z-scheme Ag3PO4/m-MIL-88A(Fe) AMM photocatalyst was successfully constructed.•The AMM heterojunctions show superior photocatalytic activity and photostability.•The Z-scheme ...mechanism with an in-situ-generated photo–Fenton process was verified.•The introduction of m-MIL-88A(Fe) benefits the in-situ photo-Fenton-like reaction.•The photocatalytic mechanism and degradation pathway were discussed in detail.
Herein, Ag3PO4/mixed-valence MIL-88A(Fe) AMM Z-scheme heterojunctions with an in-situ-generated photo–Fenton process were successfully constructed. The optimized AMM-20 heterojunctions show the maximum rate of photocatalytic TC degradation, which is 2.5 and 6.6 times of pristine Ag3PO4 and MIL-88A(Fe). The electronic and band structures of Ag3PO4, MIL-88A(Fe), m-MIL-88A(Fe) and AMM heterojunctions were deeply investigated by both experimental and theoretical simulation. The Z-scheme transfer pathway greatly accelerates the transfer rate of charge carriers and effectively inhibits the photocorrosion, leading to the improvement of photocatalytic activity and photostability. Moreover, the adjustment of the FeII/FeIII ratio of mixed-valence MIL-88A(Fe) further enhances the photocatalytic activity of the hybrid photocatalysts, benefiting from the promotion of the efficiency of the in-situ-generated photo-Fenton process. The Z-scheme transfer route coupling with an in-situ-generated photo–Fenton process was verified by the free radical trapping experiment, in-situ XPS measurement, in-situ ESR measurement, and coumarin fluorescence analysis. The degradation pathways of TC were determined through LC-MS analysis and theoretical calculation. Furthermore, the toxicity of intermediates was evaluated by QSAR prediction.
The exploitation of the stable and earth-abundant electrocatalyst with high catalytic activity remains a significant challenge for hydrogen evolution reaction. Being different from complex ...nanostructuring, this work focuses on a simple and feasible way to improve hydrogen evolution reaction performance via manipulation of intrinsic physical properties of the material. Herein, we present an interesting semiconductor-metal transition in ultrathin troilite FeS nanosheets triggered by near infrared radiation at near room temperature for the first time. The photogenerated metal-phase FeS nanosheets demonstrate intrinsically high catalytic activity and fast carrier transfer for hydrogen evolution reaction, leading to an overpotential of 142 mV at 10 mA cm
and a lower Tafel slope of 36.9 mV per decade. Our findings provide new inspirations for the steering of electron transfer and designing new-type catalysts.
Potassium ion‐batteries (PIBs) have attracted tremendous attention recently due to the abundance of potassium resources and the low standard electrode potential of potassium. Particularly, the ...solid‐electrolyte interphase (SEI) in the anode of PIBs plays a vital role in battery security and battery cycling performance due to the highly reactive potassium. However, the SEI in the anode for PIBs with traditional electrolytes is mainly composed of organic compositions, which are highly reactive with air and water, resulting in inferior cycle performance and safety hazards. Herein, a highly stable and effective inorganic SEI layer in the anode is formed with optimized electrolyte. As expected, the PIBs exhibit an ultralong cycle performance over 14 000 cycles at 2000 mA g−1 and an ultrahigh average coulombic efficiency over 99.9%.
A highly effective inorganic solid‐electrolyte interphase (SEI) layer in ether‐carbon is reported for a high performance potassium‐ion battery. The element mappings of the SEI layer demonstrate its inorganic feature open‐and‐shut. The potassium‐ion battery with the inorganic SEI layer displays a long cycle stability over 14 000 cycles.
The metallic 1T‐MoS2 has attracted considerable attention as an effective catalyst for hydrogen evolution reactions (HERs). However, the fundamental mechanism about the catalytic activity of 1T‐MoS2 ...and the associated phase evolution remain elusive and controversial. Herein, we prepared the most stable 1T‐MoS2 by hydrothermal exfoliation of MoS2 nanosheets vertically rooted into rigid one‐dimensional TiO2 nanofibers. The 1T‐MoS2 can keep highly stable over one year, presenting an ideal model system for investigating the HER catalytic activities as a function of the phase evolution. Both experimental studies and theoretical calculations suggest that 1T phase can be irreversibly transformed into a more active 1T′ phase as true active sites in photocatalytic HERs, resulting in a “catalytic site self‐optimization”. Hydrogen atom adsorption is the major driving force for this phase transition.
An irreversible phase transition of MoS2 during the photocatalytic hydrogen evolution was decrypted. Hydrogen atom adsorption is the driving force for this phase transition. The distorted structure could be stabilized by both strain and S vacancies. This phase‐transition‐induced catalytic activity improvement was defined as a “self‐optimization” mechanism.
Efficient evolution of hydrogen through electrocatalysis holds tremendous promise for clean energy. The catalytic efficiency for hydrogen evolution reaction (HER) strongly depends on the number and ...activity of active sites. To this end, making vertically aligned, ultrathin, and along with rich metallic phase WS
2
nanosheets is effective to maximally unearth the catalytic performance of WS
2
nanosheets. Metallic 1T polymorph combined with vertically aligned ultrathin WS
2
nanosheets on flat substrate is successfully prepared via one-step simple hydrothermal reaction. The nearly vertical orientation of WS
2
nanosheets enables the active sites of surface edge and basal planes to be maximally exposed. Here, we report vertical 1T-WS
2
nanosheets as efficient catalysts for hydrogen evolution with low overpotential of 118 mV at 10 mA cm
−2
and a Tafel slope of 43 mV dec
−1
. In addition, the prepared WS
2
nanosheets exhibit extremely high stability in acidic solution as the HER catalytic activity and show no degradation after 5000 continuous potential cycles. Our results indicate that vertical 1T-WS
2
nanosheets are attractive alternative to the precious platinum benchmark catalyst and rival MoS
2
materials that have recently been heavily scrutinized for hydrogen evolution.
Graphical Abstract
Vertical 1T-WS2 for hydrogen evolution.
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•1T MoS2 nanosheets were stabilized by the confinement effect of TiO2 nanotube arrays.•The architecture benefited the fast transmission of electrolyte ions and electrons.•It is the ...first report about 1T-MoS2@TiO2 nanotube arrays used in supercapacitors.•1T-MoS2@TiO2/Ti showed an excellent capacitance performance and cycle stability.
Metallic 1T phase molybdenum disulfide (1T-MoS2) holds great promise in energy storage applications due to its excellent conductivity and hydrophilicity. However, free 1T-MoS2 nanosheets are prone to agglomeration and convert to 2H-MoS2, resulting in a decrease in electrochemical performance. In this study, metallic 1T phase MoS2 nanosheets are confined among TiO2 nanotube arrays (1T-MoS2@TiO2/Ti) via a facile hydrothermal process. The architecture in the glory of ultrathin 1T-MoS2 nanosheets and highly ordered pore tunnel of TiO2 nanotube arrays benefits fast electrolyte diffusion and electron transfer. As a result, the 1T-MoS2@TiO2/Ti composite shows a high specific capacitance of 428.1F g−1 at 0.2 A g−1, high energy density of 48.2 Wh kg−1, high power density of 2481.7 W kg−1 and 97% capacitance retention after 10,000 cycles. This study proves an artful thought for designing electrode materials to enhance their electrochemical performances.
Molybdenum disulfide (MoS2) with low cost, high activity and high earth abundance has been found to be a promising catalyst for the hydrogen evolution reaction (HER), but its catalytic activity is ...considerably limited due to its inert basal planes. Here, through the combination of theory and experiment, we propose that doping Ni in MoS2 as catalyst can make it have excellent catalytic activity in different reaction systems. In the EY/TEOA system, the maximum hydrogen production rate of EY/Ni-Mo-S is 2.72 times higher than that of pure EY, which confirms the strong hydrogen evolution activity of Ni-Mo-S nanosheets as catalysts. In the lactic acid and Na2S/Na2SO3 systems, when Ni-Mo-S is used as co-catalyst to compound with ZnIn2S4 (termed as Ni-Mo-S/ZnIn2S4), the maximum hydrogen evolution rates in the two systems are 5.28 and 2.33 times higher than those of pure ZnIn2S4, respectively. The difference in HER enhancement is because different systems lead to different sources of protons, thus affecting hydrogen evolution activity. Theoretically, we further demonstrate that the Ni-Mo-S nanosheets have a narrower band gap than MoS2, which is conducive to the rapid transfer of charge carriers and thus result in multi-photocatalytic reaction systems with excellent activity. The proposed atomic doping strategy provides a simple and promising approach for the design of photocatalysts with high activity and stability in multi-reaction systems.
In this paper, doping Ni in MoS2 as catalyst can make it have excellent catalytic activity in different reaction systems. It has been proved that Ni-Mo-S nanosheet has strong hydrogen evolution activity as catalyst by combining theory and experiment. Display omitted
Defect engineering is one of the effective strategies to optimize the physical and chemical properties of molybdenum disulfide (MoS
2
) to improve catalytic hydrogen evolution reaction (HER) ...performance. Dislocations, as a typical defect structure, are worthy of further investigation due to the versatility and sophistication of structures and the influence of local strain effects on the catalytic performance. Herein, this study adopted a low-temperature hydrothermal synthesis strategy to introduce numerous dislocation-strained structures into the in-plane and out-of-plane of MoS
2
nanosheets. Superior HER catalytic activity of 5.85 mmol·g
−1
·h
−1
under visible light was achieved based on the high-density dislocations and the corresponding strain field. This work paves a new pathway for improving the catalytic activity of MoS
2
via a dislocation-strained synergistic modulation strategy.
Water pollution caused by heavy metal and organic pollutant becomes a rigorous problem, thereby a clean and sustainable technology should be developed to resolve this situation. In this work, a novel ...AgI/Bi24O31Cl10 Z-scheme photocatalysis system was designed to overcome this problem. The prepared AgI/Bi24O31Cl10 composite was characterized by many means such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). The designed Z-scheme photocatalysis system conquers difficulties of traditional photocatalysts of the fast photogenerated charge carrier recombination and weak redox ability, thereby held remarkable catalytic activity for Cr (VI) reduction and tetracycline (TC) oxidation, approximately 85.36% and 78.26% of tetracycline and Cr (VI) can be removed under visible light illumination for 1 h. Some factors like contaminant concentrations, inorganic cation, inorganic anion, and water resources on catalytic activity were explored and the influence mechanism was discoursed. Importantly, the cyclic experiment suggested that the removal efficiency did not have obvious loss after five consecutive experiments, confirming its stability and reusability. The photodegradation pathway of TC was also proposed according to liquid chromatography-mass/mass spectrometry (LC-MS) and three dimensional excitation-emission matrix fluorescence spectra (3D EEMs). Furthermore, this Z-scheme photocatalysis mechanism for Cr (VI) reduction and TC oxidation was proposed based on trapping experiment and electron spin resonance (ESR) measurement. This study sheds lights on the design of Z-scheme photocatalysis system with sunlight as driving force for refractory organic pollutants removal.
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•The novel Z-scheme AgI/Bi24O31Cl10 heterojunction photocatalyst has been first prepared.•AgI/Bi24O31Cl10 showed superior catalytic activity for Cr (Ⅵ) reduction and tetracycline oxidation.•The interfacial redox reaction was promoted.•The photogenerated charge carrier separation efficiency was enhanced.•The photodegradation pathway and photocatalytic mechanism was proposed.
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