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A theoretical analysis on the influence of photothermal effects on the photoconduction of one-dimensional (1D) carbyne nanostructures has been explored in this paper. It is found that the size dependence of photoconduction is a great benefit from the change of band structure and optical absorption, while the influence of photothermal effect on the photoconduction is mainly induced by the grain boundary scattering and transport properties. Moreover, the photoconduction increases as the incident power enhances with a P 0 γ dependence and γ is not only related to the illumination intensity but also modulated by the dimensions. Our predictions are consistent with the available evidence, which indicates that our model is crucial for the understanding of the physical mechanism on the photothermal effect of 1D carbyne nanostructures and for their potential applications in nanotechnologies. [ABSTRACT FROM AUTHOR]

2D organic crystals play a unique role in photodetection owing to their tunable detection wavelength, low manufacturing cost, compatibility with lightweight, and controllable synthesis. However, their detection wavelength range mainly encompasses the visible (Vis) and near‐infrared (NIR) spectra. Herein, 2D erucamide crystals are synthesized using nitrogen gas and methanol as raw materials without catalysts at room temperature under atmospheric pressure via laser processing. The synthesized 2D erucamide is demonstrated to be a promising broad bandgap organic semiconductor material. A UV photodetector made of 2D erucamide exhibited a responsivity as high as 145 mA W−1, a millisecond‐level response speed, and an excellent detectivity of 4.96 × 109 Jones. Furthermore, the synthesized erucamide showed an excellent UV–vis suppression ratio (R254 nm/R532 nm) of 59. The synthesis mechanism of erucamide via laser bubbling in liquids is proposed. Thermodynamically, the high temperature of the bubbles is beneficial for nitrogen and methanol decomposition. Kinetically, rapid bubble quenching facilitates final product formation. This accomplishment represented the pioneering utilization of lasers in converting nitrogen gas into organic compounds while introducing 2D erucamide into the realm of organic UV photodetectors. [ABSTRACT FROM AUTHOR]

Reducing the cost and improving the electrocatalytic activity are the key to developing high efficiency electrocatalysts for oxygen evolution reaction (OER). Here, bimetallic NiFe-based metal-organic framework (MOF) was prepared by solvothermal method, and then used as precursor to prepare NiFe-based MOF-derived materials by pyrolysis. The effects of different metal ratios and pyrolysis temperatures on the sample structure and OER electrocatalytic performance were investigated and compared. The experimental results showed that when the metal molar ratio was Fe: Ni = 1:5 and the pyrolysis temperature was 450°C, the sample (FeNi5-MOF-450) exhibits a composite structure of NiFe2O4/FeNi3/C and owns the superior electrocatalytic activity in OER. When the current density is 100 mA·cm−2, the overpotential of the sample was 377 mV with Tafel slope of 56.2 mV·dec−1, which indicates that FeNi5-MOF-450 exhibits superior electrocatalytic performance than the commercial RuO2. Moreover, the long-term stability of FeNi5-MOF-450 further promotes its development in OER. This work demonstrated that the regulatory methods such as component optimization can effectively improve the OER catalytic performance of NiFe-based MOF-derived materials. [ABSTRACT FROM AUTHOR]

As a narrow bandgap semiconductor, transition metal selenides are promising as excellent electrocatalysts for hydrogen evolution reactions (HERs). Herein, using an ultra-thin MOF as the precursor, a Co-doped core–shell shaped NiSe2 based catalyst is successfully constructed by a two-step calcination method as an efficient HER catalyst. Experiments and theoretical calculations indicate that the introduction of Co adjusts the electronic structure of Ni and Se, promoting charge transfer and reducing the energy barrier of the rate-limiting step to accelerate the hydrogen precipitation reaction. In addition, the core–shell structure contributes to mass transport, and the outer carbon layer improves the stability of the catalyst. The optimal catalyst (Ni0.75Co0.25Se2@NC) exhibited satisfactory electrocatalytic activity as evidenced by a low overpotential of −143 mV at a current density of −10 mA cm−2 and a small Tafel slope of 37.5 mV dec−1. This work provides a valuable strategy for fabricating efficient NiSe2 based electrocatalysts for the HER. [ABSTRACT FROM AUTHOR]

The evolution of cost-effective hydrogen evolution reaction (HER) electrocatalysts is of great significance for the development of clean energy. Exploring effective synthesis strategies to optimize the performance of non-noble metal electrocatalysts has always attracted our attention. Herein, ultrathin coordination polymers were used as precursors to controllably synthesize two-dimensional (2D) ultrathin dual-phase transition metal selenide (TMSs)/carbon–nitrogen (CN) composites (CoSe2–NiSe2/CN) by a two-step method (first a low temperature hydrothermal method for selenization, and then high temperature calcination selenization). Benefiting from its large specific surface area (49 m2 g−1), abundant catalytically active sites and synergistic effects, CoSe2–NiSe2/CN can significantly enhance the HER catalytic activity and exhibits good electrocatalytic activity with an overpotential of 150 mV at −10 mA cm−2, and a small Tafel slope of 42 mV dec−1 in an acidic electrolyte for the HER. This work provides a new strategy for optimizing the HER catalytic activity of TMSs by preparing 2D ultrathin dual-phase TMS composite materials. [ABSTRACT FROM AUTHOR]

Next-generation imaging systems require photodetectors with high sensitivity, polarization sensitivity, miniaturization, and integration. By virtue of their intriguing attributes, emerging 2D materials offer innovative avenues to meet these requirements. However, the current performance of 2D photodetectors is still below the requirements for practical application owing to the severe interfacial recombination, the lack of photoconductive gain, and insufficient photocarrier collection. Here, a tunneling dominant imaging photodetector based on WS 2 /Te heterostructure is reported. This device demonstrates competitive performance, including a remarkable responsivity of 402 A W -1 , an outstanding detectivity of 9.28 × 10 13 Jones, a fast rise/decay time of 1.7/3.2 ms, and a high photocurrent anisotropic ratio of 2.5. These outstanding performances can be attributed to the type-I band alignment with carrier transmission barriers and photoinduced tunneling mechanism, allowing reduced interfacial trapping effect, effective photoconductive gains, and anisotropic collection of photocarriers. Significantly, the constructed photodetector is successfully integrated into a polarized light imaging system and an ultra-weak light imaging system to illustrate the imaging capability. These results suggest the promising application prospect of the device in future imaging systems., (© 2023 Wiley-VCH GmbH.)

Carbyne with one-dimensional sp-hybridized carbon atoms is the third form of carbon following diamond and graphite. Although carbyne nanocrystals have been synthesized, little is known about its structural details. Here, we report experimental evidence of the kinked structure of carbon chains and interchain van der Waals interaction of carbyne nanocrystals by near edge X-ray absorption fine structure (NEXAFS) spectroscopy. We measure the resonance and the feature peaks of the kinked configuration of carbon chains and the van der Waals interaction between chains of carbyne nanocrystals using NEXAFS spectroscopy. We also perform theoretical calculations of density functional theory and simulations based on the super-cell core-hole method for carbon K-edge NEXAFS. The theoretical results are in good agreement with the experimental measurements, which demonstrates that carbyne nanocrystals are van der Waals crystals with kinked chains as structural units. Note that the peak at 288.5 eV in the simulated NEXAFS spectrum implies the possible presence of hydrogen-terminated kinks or hydrogen-terminated chains in carbyne nanocrystals, which clarifies the understanding of the C-H bond in carbyne nanocrystals. These findings are enlightening and significant for pursuing physics and potential applications of carbyne., Competing Interests: The authors declare that they have no competing interests., (This journal is © The Royal Society of Chemistry.)

The evolution of cost-effective hydrogen evolution reaction (HER) electrocatalysts is of great significance for the development of clean energy. Exploring effective synthesis strategies to optimize the performance of non-noble metal electrocatalysts has always attracted our attention. Herein, ultrathin coordination polymers were used as precursors to controllably synthesize two-dimensional (2D) ultrathin dual-phase transition metal selenide (TMSs)/carbon-nitrogen (CN) composites (CoSe2-NiSe2/CN) by a two-step method (first a low temperature hydrothermal method for selenization, and then high temperature calcination selenization). Benefiting from its large specific surface area (49 m2 g-1), abundant catalytically active sites and synergistic effects, CoSe2-NiSe2/CN can significantly enhance the HER catalytic activity and exhibits good electrocatalytic activity with an overpotential of 150 mV at -10 mA cm-2, and a small Tafel slope of 42 mV dec-1 in an acidic electrolyte for the HER. This work provides a new strategy for optimizing the HER catalytic activity of TMSs by preparing 2D ultrathin dual-phase TMS composite materials.