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Herein, black phosphorus (BP) quantum dots (QDs) with consistent sizes are loaded on bismuth (Bi) nanosheets (NSs) uniformly to serve as hole capturers in Group-VA monoelemental heterostructures vi...

Electrocatalytic hydrogen evolution is an exercisable way to achieve large-scale application of hydrogen energy. It is of great significance to develop an effect, stable, and cost-effective electrocatalyst. Here, we applied the two-dimensional (2D) bismuth (Bi) to the electrocatalytic hydrogen evolution, and proposed the strategies to enhance the catalytic performance of the catalyst. Due to more active sites located along the edges of 2D structure, Bi nanosheets revealed a higher electrocatalytic activity (overpotential of −958 mV vs RHE at 10 mA cm−2, Tafel slope of 122 mV/dec) than the bulk counterpart. To further evaluate the electrocatalytic performance of Bi nanosheets, the typical parameters measured in different H+ concentration (C[H+]) are carried out. The improved catalytic activity obtained in 0.5 M H2SO4 is attributed to enhancing the hydrogen adsorption and accelerating the charge transport on the surface of catalyst. Moreover, the durability of Bi nanosheets has been texted, where the current is not evident fluctuation during the 40,000 s electrolysis measurement indicating its excellent stability. The present work expands the application of Bi in the catalysis and provides the simple strategies to improve its hydrogen evolution performance.

Photoelectric detectors based on binary transition metal chalcogenides have attracted widespread attention in recent years. However, due to the high-temperature synthesis of binary TMD, high-density deep-level defect states may be generated, leading to poor responsiveness or a long response time. Besides, the addition of an alloy will change the DLDSs from deep to shallow energy levels caused by S vacancies. In this paper, MoS2(1−x)Se2x nanostructures were synthesized by a hydrothermal method, and a novel type of photodetector was fabricated by using the synthesized material as a light sensitive material. The MoSSe-based photodetector not only has a high photocurrent, but also exhibits a wide spectral response in the range of 405 nm to 808 nm. At the same time, it can achieve a responsivity of 1.753 mA W−1 under 660 nm laser irradiation of 1.75 mW mm−2. Therefore, this work can be considered as a method of constructing a new type of photodetector with a simple process and low cost.

In this report, two-dimensional (2D) bismuth selenide (Bi2Se3) nanosheets (NSs) and reduced graphene oxide (rGO) (Bi2Se3/rGO) composites have been prepared via a hydrothermal method. The microstructures and morphology properties of Bi2Se3/rGO composites were analyzed by scanning electron microscopy (SEM) and Raman spectra, indicating a well prepared and high crystalline material. Photoelectrochemical (PEC) tests demonstrate that Bi2Se3/rGO heterojunction exhibits enhanced photocatalytic performance of the pure Bi2Se3, which is about five times higher than Bi2Se3 NSs, which is because rGO acts as a conduction pathway, resulting in efficient separation of photogeneration of electron–hole pairs on the Bi2Se3/rGO composites. The as-prepared composite provides a novel insight in the field of photocatalysis.

Herein, FePS

Electrocatalytic hydrogen evolution is an exercisable way to achieve large-scale application of hydrogen energy. It is of great significance to develop an effect, stable and cost-effective electrocatalyst. Here, we applied the two-dimensional (2D) bismuth (Bi) to the electrocatalytic hydrogen evolution, and proposed the strategies to enhance the catalytic performance of the catalyst. The exfoliated Bi nanosheets via sonication assisted liquid-phase exfoliation display higher electrocatalytic activity (overpotential of -958 mV vs RHE at 10 mA cm− 2) compared to the bulk counterpart. Theoretical calculations about Gibbs free energy from the hydrogen adsorption for 1 layer, 2 layers and 5 layers Bi also manifest the decrease of thickness is favorable for hydrogen evolution reaction (HER). To further evaluate the electrocatalytic performance of Bi nanosheets, the typical parameters measured in different H+ concentration (C[H+]) are carried out. The improved catalytic activity obtained in 0.5 M H2SO4 is attributed to enhancing the hydrogen adsorption and accelerating the charge transport on the surface of catalyst. Moreover, the durability of Bi nanosheets electrode has been texted, where the current is not evident fluctuation during the 40000 s electrolysis measurement indicating its excellent stability. The present work expands the application of Bi in the catalysis and provides the simple strategies to improve its hydrogen evolution performance.

A novel MoS2/Ag2CO3 Z-scheme system was synthesized by a simple chemical depositing method. The morphology and material components of MoS2/Ag2CO3 Z-scheme system were confirmed by scanning electron microscopy and Raman spectroscopy. Photoelectrochemical (PEC) tests demonstrated that the photocurrent density of MoS2/Ag2CO3 Z-scheme system can reach up to 13 µA/cm2 in 0.5 M Na2SO4 solution at a bias voltage of 0.5 V, which is 44 times more than pure MoS2, as well as 13 times higher than pure Ag2CO3. Lastly, the stability measurement of MoS2/Ag2CO3 Z-scheme system in 0.5 M Na2SO4 solution was carried out showing no obvious difference after processing 50 cycles. This work demonstrates that the MoS2/Ag2CO3 Z-scheme system may have a great potential application in photocatalytic water splitting.

As a sustainable environmental governance strategy and energy conversion method, photocatalysis has considered to have great potential in this field due to its excellent optical properties and has become one of the most attractive technologies today. Among 2D materials, the emerging two-dimensional (2D) monoelemental materials mainly distributed in the -IIIA, -IVA, -VA and -VIA groups and show excellent performance in solar energy conversion due to their graphene-like 2D atomic structure and unique properties, thereby drawing increasing attention. This review briefly summarizes the preparation processes and fundamental properties of 2D single-element nanomaterials, as well as various modification strategies and adjustment mechanisms to enhance their photocatalytic properties. In particular, this article comprehensively discusses the related practical applications of 2D single-element materials in the field of photocatalysis, including photocatalytic degradation for contaminants removal, photocatalytic pathogen inactivation, photocatalytic fouling control and photocatalytic energy conversion. This review will provide some new opportunities for the rational design of other excellent photocatalysts based on 2D monoelemental materials, as well as present tremendous novel ideas for 2D monoelemental materials in other environmental conservation and energy-related applications, such as supercapacitors, electrocatalysis, solar cells, and so on.

Photoelectric detectors based on binary transition metal chalcogenides have attracted widespread attention in recent years. However, due to the high-temperature synthesis of binary TMD, high-density deep-level defect states may be generated, leading to poor responsiveness or a long response time. Besides, the addition of an alloy will change the DLDSs from deep to shallow energy levels caused by S vacancies. In this paper, MoS

Molybdenum Disulfide (MoS2), as a typical two-dimensional (2D) material, has abundant reserves and unique electronic structures. However, the limited number of active sites severely hinders its application in electrocatalytic oxygen evolution reaction (OER). Black phosphorus quantum dots (BP QDs), with large exposed surface areas and a mass of active edge sites, are suitable for loading on MoS2 nanosheets to form type-II heterojunctions, resulting in additional active sites and higher mobility, thereby improving the OER performance of MoS2. In addition, photo-assistance was applied to reduce high energy barriers and the energy loss, thus improving the overall efficiency of energy conversion. Here, BP QDs and MoS2 nanosheets were prepared by liquid phase exfoliation and mixed-dimensional BP QDs/MoS2 heterojunctions were constructed. The experimental results show that the BP QDs/MoS2 heterojunctions have been successfully synthesized and the OER performance of the heterojunctions outperform pure MoS2 and BP QDs, with lower onset potentials and Tafel slope. Meanwhile, both photo-assistance and changing KOH concentration can adjust the OER performance of BP QDs/MoS2 heterojunction. Furthermore, the as-prepared heterojunctions demonstrated strong stability in KOH aqueous solution. This work identifies that constructing BP QDs/MoS2 heterojunctions and photo-assistance are effective strategies to facilitate the electrocatalytic OER performance.

Herein, FePS3/reduced graphene oxide heterostructure has been prepared via a typical hydrothermal process, and flexible photodetectors based on hybrids have been subsequently fabricated. The photoresponse measurement results demonstrate that the photodetector exhibits obvious photoelectric conversion behavior without applied potential, indicating that the device possesses the capability to be self-powered. In addition, the photocurrent density of the as-fabricated photodetectors reaches up to 125 nA cm-2under 90 mW cm-2illumination intensity without an external power source, which is 5.86 times higher than single FePS3-based devices. Furthermore, the maximum attenuation in photocurrent density of the as-fabricated flexible photodetectors measured at -0.3 V after different bending cycles and bending angles is 29.8% and 17.7%, respectively. These results demonstrate that the as-fabricated photodetectors have excellent flexibility and provide a simple and effective strategy for the construction of flexible photodetectors.

The development of optoelectronics technology greatly contributes to our daily life and industrial evolution. In particular, two-dimensional (2D) materials with ultrathin structure have received worldwide research interests in the field of optoelectronics mainly owing to the intrinsic electronic and optical attributes. The on-going researches indicate that electrically conducting MOF and COF demonstrate distinctive properties and promising surface functionality, while their inherent band structure and electronic features can be rationally controlled by structural modification. With rapid development of 2D materials-based optoelectronic devices, the utilization of 2D polymer MOF and COF semiconductors has become a new tendency to meet the scope of adaptive, low-cost, and flexible device fabrication. In this review, the recent research activities on 2D MOF and COF materials are provided. The fabrication and semiconducting properties of 2D MOF and COF materials have been explained. Apart from that, both advantages and limitations of the newly developed 2D MOF and COF materials regarding their potential in optoelectronic devices have been discussed. Additionally, different types of 2D MOF and COF materials and performance adjusting strategies have been systematically summarized. Furthermore, the remaining challenges and current prospects of applying 2D MOF and COF into optical-to-electrical and electrical-to-optical conversion devices have been introduced.

Designing a Z-scheme heterojunction is of great significance to achieve high separation of photogenerated carriers and strong photo-redox properties of two semiconductor materials. In photosynthesis, the effects of photocatalytic electrolytes (adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH)) on chemical energy has attracted numerous interests. In this case, developing photocatalytic electrolytes with more active site and efficient charge extraction and separation would be beneficial for superior photocatalytic activity in Z-scheme system. Herein, we synthesized a Black/Red (BP/RP) phosphorus Z-scheme hybrid via a feasible two-steps sonochemical method, and the adding photocatalytic electrolytes ATP and NADPH in KOH solution endow the system with new vitality in photocatalysis. Consequently, photoelectrochemical (PEC) tests demonstrated the as-prepared BP/RP Z-scheme hybrid exhibits enhanced photocurrent of 9 μA/cm2 at 0.5 V compared to the sole RP, while adding NADPH and ATP, the photocurrent of BP/RP Z-scheme hybrid shows dramatic increment of 30 μA cm−2 at a bias potential of 0.6 V. The improved photocatalytic activity is ascribed to the abundant active sites, higher carrier mobility of the BP/RP Z-scheme system, as well as the efficient photogenerated carrier separation and the prolonged lifetime of photocatalytic electrolytes. This work demonstrated the photocatalytic electrolytes can meet the unity of coordination and efficiency of achieving efficient PEC catalytic in the Z-Scheme system, and provides positive ideas for the possibility and superiority for other 2D materials in the field of ultrafast Photonics, photodetectors, etc.