An appropriate solution is suggested for synthesizing wafer-scale, continuous, and stoichiometric MoS2 layers with spatial homogeneity at the low temperature of 450 °C. It is also demonstrated that the MoS2 -based visible-light photodetector arrays are both fabricated on 4 inch SiO2 /Si wafer and polyimide films, revealing 100% active devices with a narrow photocurrent distribution and excellent mechanical durability.

A step‐by‐step strategy is reported for improving capacitance of supercapacitor electrodes by synthesizing nitrogen‐doped 2D Ti2CTx induced by polymeric carbon nitride (p‐C3N4), which simultaneously acts as a nitrogen source and intercalant. The NH2CN (cyanamide) can form p‐C3N4 on the surface of Ti2CTx nanosheets by a condensation reaction at 500–700 °C. The p‐C3N4 and Ti2CTx complexes are then heat‐treated to obtain nitrogen‐doped Ti2CTx nanosheets. The triazine‐based p‐C3N4 decomposes above 700 °C; thus, the nitrogen species can be surely doped into the internal carbon layer and/or defect site of Ti2CTx nanosheets at 900 °C. The extended interlayer distance and c‐lattice parameters (c‐LPs of 28.66 Å) of Ti2CTx prove that the p‐C3N4 grown between layers delaminate the nanosheets of Ti2CTx during the doping process. Moreover, 15.48% nitrogen doping in Ti2CTx improves the electrochemical performance and energy storage ability. Due to the synergetic effect of delaminated structures and heteroatom compositions, N‐doped Ti2CTx shows excellent characteristics as an electrochemical capacitor electrode, such as perfectly rectangular cyclic voltammetry results (CVs, R2 = 0.9999), high capacitance (327 F g−1 at 1 A g−1, increased by ≈140% over pristine‐Ti2CTx), and stable long cyclic performance (96.2% capacitance retention after 5000 cycles) at high current density (5 A g−1).

The electrochemical N 2 reduction reaction has attracted interest as a potential alternative to the Haber−Bosch process, but a significantly low conversion efficiency and a significantly low ammonia production rate stimulate the need for alternatives. Here, we represent the electrochemical reduction of nitric oxide (NO) on a nanostructured Ag electrode in combination with a rationally designed electrolyte containing the EDTA−Fe 2+ metal complex (EFeMC), which results in an ∼100% efficiency for NH 3 with a current density of 50 mA/cm 2 at −0.165 V RHE , without any degradation in catalytic activity or product selectivity up to 120 h. Economic analysis using itemized cost estimation predicted that the synthesis of ammonia from NO reduction in an EFeMC-designed electrolyte can be market competitive at an electricity price of $0.03 kWh −1 with a current density of >125 mA/cm 2 . Therefore, this approach opens an entirely new avenue of renewable electricitydriven ammonia synthesis.

Recently, many experimental and theoretical efforts are being intensified to develop high-performance catalysts for electrochemical CO 2 conversion. Beyond the catalyst material screening, it is also critical to optimize the surrounding reaction medium. From vast experiments, inclusion of room-temperature ionic liquid (RTIL) in the electrolyte is found to be beneficial for CO 2 conversion; however, there is no unified picture of the role of RTIL, prohibiting further optimization of the reaction medium. Using a state-of-the-art multiscale simulation, we here unveil the atomic origin of the catalytic promotion effect of RTIL during CO 2 conversion. Unlike the conventional belief, which assumes a specific intermolecular coordination by the RTIL component, we find that the promotion effect is collectively manifested by tuning the reaction microenvironment. This mechanism suggests the critical importance of the bulk properties (e.g., resistance, gas solubility and diffusivity, viscosity, etc.) over the detailed chemical variations of the RTIL components in designing the optimal electrolyte components, which is further supported by our experiments. This fundamental understanding of complex electrochemical interfaces will help in the development of more advanced electrochemical CO 2 conversion catalytic systems in the future.

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A facile methodology for the large-scale production of layer-controlled MoS layers on an inexpensive substrate involving a simple coating of single source precursor with subsequent roll-to-roll-based thermal decomposition is developed. The resulting 50 cm long MoS layers synthesized on Ni foils possess excellent long-range uniformity and optimum stoichiometry. Moreover, this methodology is promising because it enables simple control of the number of MoS layers by simply adjusting the concentration of (NH ) MoS . Additionally, the capability of the MoS for practical applications in electronic/optoelectronic devices and catalysts for hydrogen evolution reaction is verified. The MoS -based field effect transistors exhibit unipolar n-channel transistor behavior with electron mobility of 0.6 cm V s and an on-off ratio of ≈10³. The MoS -based visible-light photodetectors are fabricated in order to evaluate their photoelectrical properties, obtaining an 100% yield for active devices with significant photocurrents and extracted photoresponsivity of ≈22 mA W . Moreover, the MoS layers on Ni foils exhibit applicable catalytic activity with observed overpotential of ≈165 mV and a Tafel slope of 133 mV dec . Based on these results, it is envisaged that the cost-effective methodology will trigger actual industrial applications, as well as novel research related to 2D semiconductor-based multifaceted applications.

Tremendous progress has been made in the investigation of 2D layered van der Waals (vdW) materials, which provide unique platforms for discovering fundamental condensed-matter phenomena. [1][2][3] In particular, heterostructures constructed from transition-metal dichalcogenides (TMD) have attracted considerable interest in the fields of physics and chemistry and for practical applications because they offer tunability of the properties, such as the band offset, carrier density, and polarity. [4][5][6][7][8] Several strategies for producing TMD-based heterostructures comprising semiconductor-semiconductor or metal-semiconductor junctions have been reported. [9][10][11] The first demonstrated TMD-based p-n junction was achieved via the mechanical stacking of microsized flakes. [4,5,12] Although the stacking method is a convenient approach for forming high-quality heterostructures for fundamental research, it relies on the probability of cleaving the bulk crystal, limiting the valuable area. For overcoming this limitation, chemical vapor deposition (CVD) has been recognized as a promising technique for forming a functional heterojunction, which can achieve not only high crystallinity but also direct synthesis of heterointerfaces with an atomically sharp boundary. [13][14][15][16][17] These TMD-based heterojunctions are pioneering advances in the fields of p-n diodes, light emitters, photodetectors, and field-effect transistors. [5][6][7][18][19][20][21][22][23] Despite such progress, it is still a grand challenging task to demonstrate the array of a hierarchical organization of the heterostructure with a controlled structure and spatial position. [24,25] In particular, the cross-aligned 1D matrix is considered as an ideal architecture for future electronics, as it significantly enhances device array integration in a limited space. [26][27][28] However, i) the complicated fabrication process involving high-temperature CVD that induces cross-contamination and ii) the unavoidable production of residues during the patterning process for defining the junction are critical hurdles for integrating the TMD heterostructure array on a large scale. [29] Recently, a novel solution-based approach has been exploited for synthesizing high-quality 2D TMD films, which is a simple and inexpensive method to control the number of layers and implement diverse structures. [30][31][32][33] Moreover, it can yield Functional van der Waals heterojunctions of transition metal dichalcogenides are emerging as a potential candidate for the basis of next-generation logic devices and optoelectronics. However, the complexity of synthesis processes so far has delayed the successful integration of the heterostructure device array within a large scale, which is necessary for practical applications. Here, a direct synthesis method is introduced to fabricate an array of self-assembled WSe 2 /MoS 2 heterostructures through facile solutionbased directional precipitation. By manipulating the internal convection flow (i.e., Marangoni flow) of the solution, ...