Enhanced Emission of Molybdenum Disulfide by Organic−Inorganic Hybrid Heterojunctions

Due to their excellent stability and layer-dependent photoelectronic properties,transition metal dichalcogenides(TMDs)are one of the most extensively studied two-dimensional semiconductor materials in the postgraphene era.However,its low luminescence quantum yield limits its application in displays,lighting,and imaging.Here,a 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile(HATCN)layer was grown on the surface of chemical vapor deposition(CVD)-grown monolayer molybdenum disulfide(MoS_(2))by vacuum evaporation,which increased the photoluminescence intensity of MoS_(2)by 15 times.The enhanced luminescence originates from the charge transfer from the conduction band of MoS_(2)to the lowest unoccupied molecular orbital(LUMO)of HATCN,which suppresses the emission of the negatively charged exciton(trion)while increasing the emission of the neutral exciton.Temperature-dependent fluorescence and Raman spectra demonstrate the feasibility of organic−inorganic hybrid heterojunctions for regulating excitons.This facile and practical organic−inorganic hybrid heterojunction can elevate TMD applications,such as light-emitting diodes.

Size dependence of photovoltaic properties and surface states modulation in ZnO nanowire/poly（3-hexylthiophene） hybrid nanostructures

An appropriate diameter and wire-to-wire dis- tance is critical for optimizing the performance of hybrid inorganic/organic photovoltaic devices. For a deep under- standing of their influences on such hybrid structures, the well-ordered ZnO nanowires with different diameters are fabricated by the versatile hydrothermal growth. The dependence of the photovoltaic performance on the surface states, wire diameter and wire-to-wire distance is investi- gated. We demonstrate that the pristine thick ZnO nanowires film possess a higher surface photovoltage （SPV） response than the thin one. This is mainly due to the influence of surface states on the thin ZnO nanowires, which can capture the photo-generated carriers. When the two kinds of ZnO nanowires are fabricated into a hybrid inorganic/organic structure, the thin ZnO nanowires/poly（3-hexylthiophene） hybrid film has a higher SPV response than the thick one, which is contrary to the pristine ZnO nanowires. This is benefited from the smaller diameter and wire-to-wire dis- tance of the thin ZnO nanowires owned. The crystallinity, wire diameter and wire-to-wire distance have the crucial influence on the final photovoltaic performance. The results shown here give us insights toward designing efficient hybrid photovoltaic devices.

High-sensitivity shortwave infrared photodetectors of metal-organic frameworks integrated on 2D layered materials

Photodetectors operating in the shortwave infrared region are of great significance due to their extensive applications in both commercial and military fields.Narrowbandgap two-dimensional layered materials(2DLMs)are considered as the promising candidates for constructing nextgeneration high-performance infrared photodetectors.Nevertheless,the performance of 2DLMs-based photodetectors can hardly satisfy the requirements of practical applications due to their weak optical absorption.In the present study,a strategy was proposed to design high-performance shortwave infrared photodetectors by integrating metalorganic frameworks(MOFs)nanoparticles with excellent optical absorption characteristics and 2DLM with high mobility.Further,this study demonstrated the practicability of this strategy in a MOF/2DLM(Ni-CAT-1/Bi_(2)Se_(3))hybrid heterojunction photodetector.Due to the transfer of photo-generated carriers from the MOF to Bi_(2)Se_(3),the MOF nanoparticles integrated on the Bi_(2)Se_(3) layer can increase the photocurrent by 2-3 orders of magnitude.The resulting photodetector presented a high responsivity of 4725 A W^(−1) and a superior detectivity of 3.5×10^(13) Jones at 1500 nm.The outstanding performance of the hybrid heterojunction arises from the synergistic function of the enhanced optical absorption and photogating effect.In addition,the proposed device construction strategy combining MOF photosensitive materials with 2DLMs shows a high potential for the future high-performance shortwave infrared photodetectors.

Regulating electronic structure of two-dimensional porous Ni/Ni_(3)N nanosheets architecture by Co atomic incorporation boosts alkaline water splitting

Interfacial engineering is a powerful method to improve the bifunctional electrocatalytic performance of pure phase catalysts.While it is expected to further optimize the electronic configuration of heterojunctions to boost the reaction kinetics in hydrogen/oxygen evolution reaction(HER/OER),but remains a challenge.Herein,a novel in situ hybrid heterojunction strategy is developed to construct 2D porous Co-doped Ni/Ni_(3)N heterostructure nanosheets(Co-Ni/Ni_(3)N)by pyrolysis of partially cobalt substituted nickel-zeolitic imidazolate framework(CoNi-ZIF)nanosheets under NH3 atmosphere.A combined experimental and theoretical studies manifest that the hybrid heterostructures can display regulative electronic states and downshift d-band center from the Fermi level,as well as optimize the adsorption energy of reaction intermediates,thus reducing the thermodynamic energy barriers and accelerating the catalytic kinetics.Consequently,benefitting from the optimized electronic configuration,hierarchical hollow nanosheets architecture,and abundant doped heterojunctions,the hybrid Co-Ni/Ni_(3)N heterostructure catalyst exhibits efficient catalytic activity for both HER(60 mV)and OER(322 mV)at 10 mA cm^(-2)in alkaline media,which is 105 and 47 mV lower than that of pure Ni_(3)N,respectively.The electrochemically active surface area of Co-Ni/Ni_(3)N is two times higher than that of Ni3N.Furthermore,the coupled practical water electrolyzer requires a low voltage of 1.575 V to reach 10 mA cm^(-2),and it can be driven by a 1.5 V battery.This work highlights the interface engineering guidance for the rational establishment of hybrid interfaces by electronic modulation of interfacial effect for alkaline water splitting.