Two-dimensional Sheets Research Articles

Bose glass and Fermi glass

It is known that two-dimensional superconducting materials undergo a quantum phase transition from a localized state to superconductivity. When the disordered samples are cooled, bosons (Cooper pairs) are generated from Fermi glass and reach superconductivity through Bose glass. However, there has been no universal expression representing the transition from Fermi glass to Bose glass. Here, we discovered an experimental renormalization group flow from Fermi glass to Bose glass in terms of simple beta-function analysis. To discuss the universality of this flow, we analyzed manifestly different systems, namely a Nd-based two-dimensional layered perovskite and an ultrathin Pb film. We find that all our experimental data for Fermi glass fall beautifully into the conventional self-consistent beta-function. Surprisingly, however, flows perpendicular to the conventional beta-function are observed in the weakly localized regime of both systems, where localization becomes even weaker. Consequently, we propose a universal transition from Bose glass to Fermi glass with the new two-dimensional critical sheet resistance close to R_Box = h/e^{2}.

Synthesis and characterization of bio-nanocomposites: Functionalization of graphene oxide with a biocompatible amino acid

Graphene oxide (GO) is a complicated composite which can be synthesized from graphite or other carbon sources by a simple top-down method. Graphene is a two-dimensional carbon sheets which can be oxidized to synthesis its oxide structure. The graphene oxide sheets can be functionalized in order to be used actively in different areas. The graphene oxide nanocomposite materials have attracted researches and scientists’ attention due to their wade applications from electrochemical industry to drug delivery. In this novel work the authors have synthesized graphene oxide films and then functionalized with an amino acid, Lysine, and Cu in order to synthesize the Lysine-Cu-Graphene oxide combination. The novelty of this investigation is the authors have functionalized graphene oxide with l-lysine as an amino acid at diverse temperature. Also, this product is environmentally friendly product since it is soluble in aqueous medium and can be applied as an active antibacterial material. After the synthesizing process, the obtained materials had been characterized using different techniques such as Fourier-transform infrared spectroscopy (FTIR) to confirm the success of the functional reaction. Ultra violet visible (UV–Vis) spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal gravimetric (TG) analysis, were also utilized to approve the covalent attachment of Lysine and also to show the improvement in the thermal stability of GO.

Efficient CO2 separation by ionic liquid nanoconfined in ultra-thin TCOH@Pebax-1657 MMM

Global climate change has continued to intensify in recent years, and the low efficiency of carbon emission reduction has become an important issue for many countries. Membrane separation technology has gained popularity in CO2 capture due to its ease of operation, environmental friendliness, and smaller area, etc. Two-dimensional (2D) sheet materials are one of the most promising materials for membrane separation technology. MXene has been used for gas separation because of its advantages such as high aspect ratio, excellent flexibility, and rich functional group surface. However, the stacking of massive MXene nanosheets lead to gas transport channel obstruction, causing the gas permeance to decrease. Herein, the hydroxylation of MXene was treated to obtain alkaline MXene nanosheets (TCOH) in this work. The stabilised TCOH and Pebax-1657 were used to make a mixed matrix membrane (MMM), while 1-ethyl-3-methylimidazolyl acetate ([EMIm][AcO], IL) was nanoconfined in the 2D channel of ultra-thin TCOH@Pebax-1657 MMM to construct a novel composite membrane for efficient CO2 capture. The TCOH@Pebax-1657/IL membrane prepared in this experiment has high CO2 permeance and the selectivity of CO2/N2, CO2/CH4 at the IL concentration of 35 wt%. In addition, the film has shown excellent thermal stability and durability over long periods of testing. Since TCOH is rarely used in the field of gas separation, the study will provide fresh idea for the preparation of highly efficient CO2 capture membranes.

N-Cyclo-hexyl-tryptamine: freebase, bromide and fumarate.

The solid-state structures of N-cyclo-hexyl-tryptamine (I) {systematic name: N-[2-(1H-indol-3-yl)eth-yl]cyclo-hexa-namine}, C16H22N2, and two of its salts, N-cyclo-hexyl-tryptammonium bromide (II) {systematic name: N-[2-(1H-indol-3-yl)eth-yl]cyclo-hexa-naminium bromide}, C16H23N2 +·Br-, and N-cyclo-hexyl-tryptammonium fumarate (III) (systematic name: bis-{N-[2-(1H-indol-3-yl)eth-yl]cyclo-hexa-naminium} (2E)-but-2-enedioate), 2C16H23N2 +·C4H2O4 2-, were determined by single-crystal X-ray diffraction. The freebase compound forms infinite chains along [010] through N-H⋯N hydrogen bonds. The bromide salt is held together by N-H⋯Br inter-actions in two-dimensional sheets along (001). The fumarate salt is held together in infinite three-dimensional frameworks by N-H⋯O hydrogen bonds.

Robust Proton Conduction against Mechanical Stress in Flexible Free-Standing Membrane Composed of Two-Dimensional Coordination Polymer.

Introduction of mechanical flexibility into proton-conducting coordination polymers (CPs) is in high demand for future protonic applications such as fuel cells and hydrogen sensors. Although such mechanical properties have been primarily investigated in one-dimensional (1D) CPs, in this study, we successfully fabricated highly flexible free-standing CP membranes with a high surface-to-volume ratio, which is beneficial for enhanced performance in the aforementioned applications. We fabricated a layered CP, Cu2 (NiTCPP) (H4 (H2 TCPP); 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin), in which a two-dimensional (2D) square grid sheet composed of tetradentate nickel porphyrins and paddlewheel-type copper dimers was connected to each other by weak van der Waals forces. The mechanical flexibility was evaluated by bending and tensile tests. The flexural and Young's moduli of the membrane were significantly higher than those of conventional Nafion membranes. Electrochemical impedance spectroscopy analysis revealed that the in-plane proton conductivity of the membrane was maintained even under applied bending stress. Because the X-ray diffraction analysis indicates that the proton-conducting pathway through the hydrogen bonding network remains intact during the bending operation, our present study provides a promising strategy for the fabrication of new and advanced 2D CPs without using substrates or additional polymers for protonic devices.

MoS2-GO hybrid sensor: A discerning approach for detecting harmful H2S gas at room temperature

The molybdenum disulfide (MoS2)- graphene oxide (GO) hybrids have fashioned by a clean hydrothermal route. Initially, two-dimensional GO sheets have synthesized using the modified Hummer’s method and intercalated into the MoS2 nanoparticles (NPs). The sophisticated characterizations comprising X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analyzer, custom designed gas sensing set-up, etc. utilized for the analysis of as-prepared MoS2-GO (1 to 5 wt%) hybrids. The maximum sensor response exhibited by as-prepared MoS2-GO (3%) hybrid sensor was 39.16% towards 100 ppm hydrogen sulfide (H2S) gas at room temperature (RT, i.e., 28 °C) in a quickest response time (6.13 s) and least concentration of H2S detected was 1 ppm with response value 0.51%. This report investigated first time that as-prepared MoS2-GO (MG) hybrids with varied proportion of GO (1 to 5 wt%) demonstrated spectacularly improved gas sensing performance towards H2S at RT. The boosted gas sensing performance of MG hybrids could be attributed to the synergistic influence of constituents i.e., MoS2 NPs and GO sheets. An impedance spectroscopy has been exploited to study the interactions between H2S gas molecules and MG hybrid sensor surface.

Crystal structure of poly[(aceto-nitrile-κN)(μ3-7-{[bis-(pyridin-2-ylmeth-yl)amino]-meth-yl}-8-hy-droxy-quinoline-5-sulfonato-κ4N,O:O':O'')sodium

In the title compound, [Na(C22H19N4O4S)(CH3CN)]n, the NaI atom adopts a distorted square-pyramidal coordination geometry, formed by one N and one O atom of the qunolinol moiety in the ligand, two O atoms of sulfonate moieties of two adjacent ligands and the N atom of the coordinated aceto-nitrile solvent. The NaI atom is located well above the mean basal plane of the square-based pyramid. The apical position is occupied by a sulfonate O atom of a neighboring ligand. Three N atoms of the bis-(pyridin-2-ylmeth-yl)amine moiety in the ligand are not coordinated by the sodium atom. The mol-ecule forms an intra-molecular bifurcated O-H⋯[N(tertiary amine),N(pyridine)] hydrogen bond, generating S(6) and S(5) rings. In the crystal, four mol-ecules are linked by four Na-O(sulfonato) bridged coordination bonds, forming a supra-molecular centrosymmetric tetra-mer unit comprising an eight-membered ring, and generating a two-dimensional network sheet. The mol-ecules of different sheets form inter-molecular C-H⋯O hydrogen bonds, and thereby a three-dimensional network structure.

Investigation of the collisionless plasmoid instability based on gyrofluid and gyrokinetic integrated approach

In this work, the development of two-dimensional current sheets with respect to tearing modes, in collisionless plasmas with a strong guide field, is analysed. During their nonlinear evolution, these thin current sheets can become unstable to the formation of plasmoids, which allows the magnetic reconnection process to reach high reconnection rates. We carry out a detailed study of the effect of a finite $\beta _e$ , which also implies finite electron Larmor radius effects, on the collisionless plasmoid instability. This study is conducted through a comparison of gyrofluid and gyrokinetic simulations. The comparison shows in general a good capability of the gyrofluid models in predicting the plasmoid instability observed with gyrokinetic simulations. We show that the effects of $\beta _e$ promotes the plasmoid growth. The effect of the closure applied during the derivation of the gyrofluid model is also studied through the comparison among the variations of the different contributions to the total energy.

High-performance solid-state asymmetric Supercapacitor based on α-Fe2O3/r-GO/GCN composite electrode material for energy storage application

Herein, a 3D/2D/2D of α-Fe2O3/r-GO/GCN composites were synthesized by combined reflux condensation and sonochemical-assisted wet-impregnation techniques. The physicochemical properties of the prepared materials were inspected by various analytical techniques. Morphology analysis techniques of different electron microscopes were employed to confirm the rhombohedral (3D) and two-dimensional (2D) sheets' morphology. The electrochemical behaviour of the as-synthesised electrode materials was assessed for use in a redox electrolyte-based energy storage system. Electrochemical measurements in a 6M KOH solution revealed that the electrode exhibited good supercapacitive behaviour. The 3D/2D/2D -α-Fe2O3/r-GO/GCN composite had a higher capacitance rate of roughly 810 F g−1 than α-Fe2O3 nanoparticles at 1Ag−1. From cyclic stability, ternary composite has good cyclic retention (98.9%) after 10,000 cycles at 10 Ag−1. The surface characteristics of metal oxide nanostructures and the efficient conductive networks of r-GO and GCN sheets are primarily responsible for the ternary α-Fe2O3/r-GO/GCN composite's superior electrochemical performance. Asymmetric supercapacitor (ASC) devices were constructed using 3D/2D/2D anodic material and activated carbon as a cathode material with a power density of 929 Wkg−1, energy density of 40 WhKg−1, and 92 % of capacity retention.

Uracil derivative-assisted universal synthesis of defective 2-dimensional porous flaky carbon nitride for efficient photocatalytic CO2 reduction

In this paper, three novel defective two-dimensional lamellar carbon nitride were successfully synthesized by molecular self-assembly using melamine and cyanuric acid as supramolecular aggregates and introducing three different uracil derivatives (5-formyluracil, 5-acetyluracil, uracil-5-carboxylic acid). In our previous work, we found that the introduction of thymine into supramolecular precursors has good photocatalytic oxidation ability for NO. On this basis, we discovered that by introducing uracil derivatives as ligands for supramolecular aggregates, not only two-dimensional porous sheet nanostructures can be constructed, but also abundant nitrogen and oxygen defects can be introduced, which is supported by various characterizations. These defects can effectively modulate the electronic structure of carbon nitride and thus improve the separation of photogenerated carriers. In addition, the introduction of uracil derivatives affects the energy band structure of the catalyst, and these are important factors affecting the catalytic activity. Compared with bulk carbon nitride, the synthesized materials exhibited significantly enhanced photocatalytic CO2 reduction activity under mild conditions, with CO yields of 10.34, 28.65, 32.28, and 36.48 μmol g−1h−1 for BCN, CNU2.5, CNF2.5, and CNY2.5, respectively. More importantly, with the support of in situ DRIFTS, we proposed the reaction mechanism of photocatalytic reduction of CO.

Computational pulmonary edema: A microvascular model of alveolar capillary and interstitial flow.

We present a microvascular model of fluid transport in the alveolar septa related to pulmonary edema. It consists of a two-dimensional capillary sheet coursing by several alveoli. The alveolar epithelial membrane runs parallel to the capillary endothelial membrane with an interstitial layer in between, making one long septal tract. A coupled system of equations uses lubrication theory for the capillary blood, Darcy flow for the porous media of the interstitium, a passive alveolus, and the Starling equation at both membranes. Case examples include normal physiology, cardiogenic pulmonary edema, acute respiratory distress syndrome (ARDS), hypoalbuminemia, and effects of PEEP. COVID-19 has dramatically increased ARDS in the world population, raising the urgency for such a model to create an analytical framework. Under normal conditions fluid exits the alveolus, crosses the interstitium, and enters the capillary. For edema, this crossflow is reversed with fluid leaving the capillary and entering the alveolus. Because both the interstitial and capillary pressures decrease downstream, the reversal can occur within a single septal tract, with edema upstream and clearance downstream. Clinically useful solution forms are provided allowing calculation of interstitial fluid pressure, crossflows, and critical capillary pressures. Overall, the interstitial pressures are found to be significantly more positive than values used in the traditional physiological literature. That creates steep gradients near the upstream and downstream end outlets, driving significant flows toward the distant lymphatics. This new physiological flow provides an explanation to the puzzle, noted since 1896, of how pulmonary lymphatics can function so far from the alveoli: the interstitium is self-clearing.

Modulating the electronic structure of CoFeCNO 2D nanosheets via Ni incorporation for efficient electrochemical oxygen evolution

Electronic modulation of electrocatalytic active sites by heteroatom doping has been widely recognized as an effective synthetic strategy to further enhance the intrinsic activity of oxygen evolution electrocatalysts. Incorporation of heteroatoms with different atomic radius and electronegativity into the material's lattice helps to induce subtle distortions in the material's lattice and redistribution of electron density, thereby precisely changing the electronic structure at the atomic level and enhancing catalysis active. By adjusting the ratio of metal and non-metal elements, a series of CoFeNiCNO sheet-like oxygen evolution electrocatalysts were prepared. Electrochemical characteristics showed that the overpotential of bimetallic CoFeNiCNO catalysts corresponding to 10 mA cm−2 only needs 290 mV, the Tafel slope is 98 mV dec−1, and it also has superior electrochemical stability in alkaline solution compared with that of bimetallic CoFeCNO catalysts. The doping of Ni ions in the material is closely related to the two-dimensional sheet structure of the material. This work provides a new idea for the preparation of low-cost nanosheet electrocatalysts for oxygen evolution, which is expected to be applied on a large scale in production and life.

Contraction of infinite-long air sheet at capillary-inertial regime

The contraction of a two-dimensional infinite-long flat air sheet in a liquid environment at a capillary-inertial regime with an Ohnesorge number Oh ⩽ 0.01 was investigated numerically. The contraction velocity first increases to a maximum and then decreases and follows a scaling U*∼t*−0.2. In this range of Oh number, pinch-off and oscillation were always observed, and two pinch-off mechanisms were identified as end-pinching (Oh ⩽ 0.006) and oscillation-induced pinch-off (Oh ⩾ 0.007), which also correspond to two oscillation regimes of the rim. Different modes of vortex shedding and merging, co-rotating, and separation of vortices are observed; the interaction between the rim and the vortices is responsible for the complicated contraction dynamics.

Kinetic Equilibrium of Two-dimensional Force-free Current Sheets

Force-free current sheets are local plasma structures with field-aligned electric currents and approximately uniform plasma pressures. Such structures, widely found throughout the heliosphere, are sites for plasma instabilities and magnetic reconnection, the growth rate of which is controlled by the structure’s current-sheet configuration. Despite the fact that many kinetic equilibrium models have been developed for one-dimensional force-free current sheets, their two-dimensional (2D) counterparts, which have a magnetic field component normal to the current sheets, have not received sufficient attention to date. Here, using particle-in-cell simulations, we search for such 2D force-free current sheets through relaxation from an initial, magnetohydrodynamic equilibrium. Kinetic equilibria are established toward the end of our simulations, thus demonstrating the existence of kinetic force-free current sheets. Although the system currents in the late equilibrium state remain field aligned as in the initial configuration, the velocity distribution functions of both ions and electrons systematically evolve from their initial drifting Maxwellians to their final time-stationary Vlasov state. The existence of 2D force-free current sheets at kinetic equilibrium necessitates future work in discovering additional integrals of motion of the system, constructing the kinetic distribution functions, and eventually investigating their stability properties.

Magnetic properties of 3d metal atoms embedded in a new two-dimensional carbon sheet

A first-principles study is performed to explore the magnetic properties of the 3d transition metal (TM) atoms embedded in a new two-dimensional(2D) nonmagnetic carbon sheet. By the adsorption of 3d metal atoms (M = Sc-Ni) on the single vacancy (SV) site of 2D carbon material, the M@SV complexes are nonmagnetic for M = Ti, Co and Ni. Other metal atoms doping can induce different magnetism. The magnetic moment of Sc@SV system mainly comes from the π electrons of carbon atoms, and these electrons virtual hopping leads to the ferromagnetic coupling interaction with Sc atom. For M = V, Cr, Mn and Fe systems, the more net spin electrons go the separate nonbonding d orbitals, giving the different magnetic moments. Meanwhile, due to the Hund’s rule, the metal atoms and the surrounding carbon atoms have the anti-ferromagnetic coupling interaction. By the simple spd hybridization model, we explore the origin of the various magnetism, and provide some new magnetic single-atom materials for the future spintronics devices and spin-dependent catalysts.

Versatile Bifunctional Ag@g-C3N4/r-GO Catalyst for Efficient Photo- and Electrocatalytic H2 Production

Here, we develop a series of hybrid Ag@g-C3N4/r-GO nanocomposite materials that are highly active, durable, and adaptable for electro- and photocatalytic H2 generation under visible light by employing a rapid and simple sonochemical technique. Multiple catalytic behaviors can be achieved through the strategic introduction of Ag metal into a hierarchical structure consisting of photo- and electroactive two-dimensional (2D) sheets with various band configurations. The outcomes of this work show the development of heterojunctions and show how electro- and photocatalysis were both synergistically improved. The fabricated materials were examined for photocatalytic hydrogen evolution, photoelectrocatalytic (PEC) hydrogen evolution, and electrocatalytic hydrogen evolution reaction (HER). In both photocatalytic conditions at 1.5 AM simulated light irradiation and electrocatalytic conditions, silver-doped composites showed better activity. Among all of the fabricated catalysts, the Ag20%@g-C3N4/r-GO (A20CNG) catalyst displayed the highest apparent quantum yield (AQY) of 1.69 and the highest hydrogen generation rate (954 μmol g–1 h–1). However, in the case of electrocatalysis, Ag15%@g-C3N4/r-GO (A15CNG) showed impressive HER activity with a low overpotential (η) of 0.484 V at 10 mA cm–2 current density with 130.6 mV dec–1 Tafel slope value and also exhibited approximately 16 times more current density than that of g-C3N4/GO (CNGO) at a fixed overpotential in the HER process; this was also supported by the electrochemical active surface area (ECSA). On the basis of the impressive results shown above, the Ag@g-C3N4/r-GO (ACNG) catalyst might be a promising and flexible nanocomposite for photo-, photoelectro-, and electrocatalytic hydrogen evolutions. This is the first study to our knowledge that provides the results of a comprehensive examination into the photo- and electrocatalytic application of an interesting and versatile bifunctional catalyst.

Permselective and transparent wooden membrane with artemisinin-imprinted nanocages based on a MOFs@C3N4 self-assembly design

Molecularly imprinted membranes have superior selective separation capacity, rebinding capacity, and flux due to their microporous substrates and tightly packed molecularly imprinted polymers. In current study, artemisinin (Ars), the most effective antimalarial drug, is used as template molecule. The permeation-selectivity wooden membranes based on Ars-imprinted nanocages designed by metal organic framework@carbon nitride self-assembly process (MDWMs) has been successfully prepared: (i) based on three-dimensional mesoporous basswood membranes, dopamine-based auto-polymerization process was developed on basswood to for harvest the first layer imprinting and secondary reaction platform. (ii) The two-dimensional sheet carbon nitride modified by metal-organic framework is stably loaded on the surface of the polydopamine-modified basswood membrane, providing a rich irregular point array structure for the formation of recognition sites. Based on elaborate designs and optimizations, selectivity, rebinding capabilities, and flux are enhanced on the developed MDWMs (βAre/Ars = 6.49, βAru/Ars = 4.22, βDH-Ars/Ars = 7.42), and high regeneration rate (>94% after 10 cycles) indicates that MDWMs have superior selectivity and stability. The MDWMs and preparation strategies developed here will provide a completely new design methodology for subsequent selective separation of Ars.

Effect of thermal annealing on physical, structural, and performance variation of graphene oxide: A review

Graphene is a two-dimensional monolayer planar sheet containing carbon atoms that are sp2-bonded to one other and tightly packed in a honeycomb crystal structure. Because of its extraordinary qualities, graphene and its derivatives, such as functionalized graphene, graphene oxide (GO), and reduced graphene oxide (rGO), have attracted substantial attention in a variety of applications. The synthesis of graphene and its derivatives of high quality can be accomplished by the employment of a several different methods. When subjected to various reduction methods, GO and rGO emerge with distinctive sets of properties. These features, in turn, have an impact on the graphene’s overall usefulness and performance. This paper provides an overview of the influence that thermal annealing has on the structural and physical properties of graphene. Following the thermal annealing, GO was converted into rGO, and this allowed for the coherent crystal structure of rGO to be restored. It has been found that the annealing temperature has a direct relationship with the crystallite size. The results of the recorded Raman spectra demonstrate that the degree of imperfection ([Formula: see text] ratio) can sometimes be found to increase while at other times it can be found to decrease. There has not been any conclusive evidence to support either the hypothesis that annealing is employed to polish graphene or the hypothesis that this can lead to changes in doping, defect levels, and strain consequences. Additionally, the impact that thermal annealing has on the functionality and performance variations of rGO has been analyzed and explained. This study concluded with a concise review, a discussion of the challenges faced, and a discussion of the opportunities presented by the graphene.

Palladium-Phosphide-Modified Three-Dimensional Phospho-Doped Graphene Materials for Hydrogen Storage.

The development of efficient hydrogen storage materials is crucial for advancing hydrogen-based energy systems. In this study, we prepared a highly innovative palladium-phosphide-modified P-doped graphene hydrogen storage material with a three-dimensional configuration (3D Pd3P0.95/P-rGO) using a hydrothermal method followed by calcination. This 3D network hindering the stacking of graphene sheets provided channels for hydrogen diffusion to improve the hydrogen adsorption kinetics. Importantly, the construction of the three-dimensional palladium-phosphide-modified P-doped graphene hydrogen storage material improved the hydrogen absorption kinetics and mass transfer process. Furthermore, while acknowledging the limitations of primitive graphene as a medium in hydrogen storage, this study addressed the need for improved graphene-based materials and highlighted the significance of our research in exploring three-dimensional configurations. The hydrogen absorption rate of the material increased obviously in the first 2 h compared with two-dimensional sheets of Pd3P/P-rGO. Meanwhile, the corresponding 3D Pd3P0.95/P-rGO-500 sample, which was calcinated at 500 °C, achieved the optimal hydrogen storage capacity of 3.79 wt% at 298 K/4 MPa. According to molecular dynamics, the structure was thermodynamically stable, and the calculated adsorption energy of a single H2 molecule was -0.59 eV/H2, which was in the ideal range of hydrogen ad/desorption. These findings pave the way for the development of efficient hydrogen storage systems and advance the progress of hydrogen-based energy technologies.

1T/1H-SnS2 Sheets for Electrochemical CO2 Reduction to Formate.

Understanding the catalytic mechanism of highly active two-dimensional electrocatalysts is crucial to their rational design. Herein, we reveal the element dependence of the reactivity of two-dimensional metal dichalcogenide sheets for electrocatalytic CO2 reduction. We found that tin(IV) disulfide (SnS2) and molybdenum(IV) disulfide (MoS2) sheets exhibited Faradaic efficiencies of 63.3% and ∼0%, respectively, for formic acid. Scanning electrochemical cell microscopy and theoretical calculations were used to identify the catalytically active sites of SnS2 as terraces and edges. Owing to the effective utilization of the entire surface area, SnS2 can effectively accelerate catalytic reactions. This finding provides a direction for material research in two-dimensional electrocatalysts for energy-efficient chemical production from electrochemical CO2 reduction, as well as for other energy devices.