Phosphorus Heterojunction Research Articles

Tailoring band structures and photocatalytic overall water splitting in a two-dimensional GaN/black phosphorus heterojunction: First-principles calculations

Tailoring band structures and photocatalytic overall water splitting in a two-dimensional GaN/black phosphorus heterojunction: First-principles calculations

Non-volatile 2D MoS2/black phosphorus heterojunction photodiodes in the near- to mid-infrared region

Cutting-edge mid-wavelength infrared (MWIR) sensing technologies leverage infrared photodetectors, memory units, and computing units to enhance machine vision. Real-time processing and decision-making challenges emerge with the increasing number of intelligent pixels. However, current operations are limited to in-sensor computing capabilities for near-infrared technology, and high-performance MWIR detectors for multi-state switching functions are lacking. Here, we demonstrate a non-volatile MoS2/black phosphorus (BP) heterojunction MWIR photovoltaic detector featuring a semi-floating gate structure design, integrating near- to mid-infrared photodetection, memory and computing (PMC) functionalities. The PMC device exhibits the property of being able to store a stable responsivity, which varies linearly with the stored conductance state. Significantly, device weights (stable responsivity) can be programmed with power consumption as low as 1.8 fJ, and the blackbody peak responsivity can reach 1.68 A/W for the MWIR band. In the simulation of Faster Region with convolution neural network (CNN) based on the FLIR dataset, the PMC hardware responsivity weights can reach 89% mean Average Precision index of the feature extraction network software weights. This MWIR photovoltaic detector, with its versatile functionalities, holds significant promise for applications in advanced infrared object detection and recognition systems.

Enhancement of Broadband Reverse Saturable Absorption of Red/Black Phosphorus Heterojunction.

Although laser technology brings convenience to production and daily life, it also causes high-energy damage. Therefore, there is an urgent need to develop optical limiting materials for laser protection. In this study, a novel nonlinear optical material, red/black phosphorus lateral heterojunction, is successfully prepared through solvothermal and ultrasonic treatment. Using the Z-scan method, the nonlinear optical properties of the red/black phosphorus heterojunction are determined at wavelengths of 532 and 1064 nm. These results indicate that the red/black phosphorus heterojunction exhibits reverse saturable absorption properties in 1.2.3-glycerol. Interestingly, the red/black phosphorus heterojunction shows an enhanced performance over red phosphorus by introducing the black phosphorus phase. Moreover, the red/black phosphorus heterojunction is doped into organically modified silicate gel glass with excellent broadband optical limiting performance. This study highlights the promising prospect of the red/black phosphorus heterojunction in the nonlinear optical and optical limiting fields.

All-optical switching based on spatial self-phase modulation of Ag/violet phosphorus heterojunctions.

With the increasing demand for high-performance passive nonlinear photonic devices, significant progress has been made in spatial self-phase modulation (SSPM) based on 2D nanomaterials in all-optical switches, logic gates, and information converters in recent years. However, there are still challenges in improving the responsiveness of photonic devices. In this work, we prepared a heterojunction of Ag nanoparticles deposited on the surface of violet phosphorus nanosheets (VP Ns), investigated their SSPM, and demonstrated their performance in all-optical switches. The SSPM experimental results show that compared with pure VP Ns at the same light intensity, both the maximum number and the formation time of self-diffraction rings in Ag/VP heterojunctions increase, and the nonlinear refractive index is approximately doubled. The main reason for optical nonlinearity enhancement is that the internal electric field in the heterojunction strengthens the mobility of the photogenerated carrier, thereby enhancing its optical nonlinearity. In particular, we demonstrate the performance of all-optical switches based on SSPM by utilizing the superior optical nonlinearity of Ag/VP heterojunctions. It is shown that with the increase of low-dose Ag content in heterojunctions, the switching time in the all-optical switch becomes shorter and the maximum number of self-diffraction rings of the signal light increases, although the quality of self-diffraction rings slightly decreases due to the scattering of Ag particles. The results contribute to the design and implementation of high-performance nonlinear photonic devices, based on the use of heterojunctions with low-cost preparation and a high nonlinear refractive index.

Ferrous Selenide Stabilized Black Phosphorus Heterojunction Sonosensitizer for MR Imaging-Guided Sonodynamic Therapy of Bladder Cancer.

It is urgent to develop an alternative dynamic therapy-based method to overcome the limited efficacy of traditional therapy methods for bladder cancer and the damage caused to patients. Sonodynamic therapy (SDT) has the advantages of high tissue penetration, high spatiotemporal selectivity, and being non-invasive, representing an emerging method for eradicating deep solid tumors. However, the effectiveness of SDT is often hindered by the inefficient production of reactive oxygen species and the nondegradability of the sonosensitizer. To improve the anti-tumor effect of SDT on bladder cancer, herein, a BP-based heterojunction sonosensitizer (BFeSe2) was synthesized by anchoring FeSe2 onto BP via P-Se bonding to enhance the stability and the effect of SDT. As a result, BFeSe2 showed great cytotoxicity to bladder cancer cells under ultrasound (US) irradiation. BFeSe2 led to a notable inhibition effect on tumor growth in subcutaneous tumor models and orthotopic tumor models under US irradiation. In addition, BFeSe2 could also enhance T2-weighted magnetic resonance imaging (MRI) to achieve monitoring and guide treatment of bladder cancer. In general, BFeSe2 sonosensitizer integrates MRI functions for precise treatment, promising great clinical potential for the theranostics of bladder cancer.

Fabrication of S-scheme FeCoS2/Red phosphorus heterojunction for efficient photocatalytic H2 evolution

Establishing efficient charge transfer channels remains a great challenge to improve the photocatalytic activity of red phosphorus (RP). Herein, the flower-like spherical FeCoS2 was employed to improve the activity of RP nanosheets, S-scheme FeCoS2/RP heterojunction was obtained through a facile solvent evaporation strategy. The optimized 5 wt% FeCoS2/RP exhibited an excellent H2 evolution rate of 2254.2 μmol g−1 h−1, which is 17.5 and 71.1-fold than that of pristine RP (129.1 μmol g−1 h−1) and FeCoS2 (31.7 μmol g−1 h−1), respectively. The analysis shows that bimetallic sulfides FeCoS2 can not only increase the electrochemically active surface area, decrease the H2 evolution overpotential and water contact angle of the composite, but also provide more photoinduced charges and reduce their transfer resistance, more importantly, the charge transfer between FeCoS2 and RP follows the S-scheme route, which can reserve the electrons and holes with higher the thermodynamic driving force. Further investigation shows that the activity of FeCoS2 is superior to monometallic sulfides FeS and CoS due to its synergistic effect between Fe and Co. This work provides new insights for constructing S-scheme RP-based heterojunction with high photocatalytic efficiency and stability.

Synergetic removal of mixed pollutants over cerium oxide/red phosphorus heterojunction composite

CeO2/hydrothermally treated red phosphorus (HRP) heterojunction composite was formed to address the easy recombination of carriers. The results of the composition proportion optimization revealed that the 5%CeO2/HRP composite (weight proportion of CeO2 about 5wt%) showed the best photocatalytic degradation performance for Rhodamine B (RhB). The rate constant value of 5%CeO2/HRP was 0.071 min−1, which was 2.0 and 35.5 times more than that of pure HRP and CeO2. In addition, the introduction of the heavy metal Cr(VI) to form a mixed heavy metal-organic pollutant solution significantly improved the removal of RhB due to the simultaneous removal of the two target pollutants could improve the utilization efficiency of photogenerated carriers. Mechanistic investigations proved that the heterojunction could be decreased the recombination ratio of photogenerated electron-hole pairs in single semiconductors, thereby enhancing its photocatalytic activity. This research not only offered a novel method for designing heterojunction photocatalytic materials, but also provided a fresh perspective on the treatment of mixed pollutants.

Bi2WO6/red phosphorus heterojunction photocatalyst with excellent visible light photodegrading activity

Red phosphorus (RP) was limited in photocatalytic activity due to the rapid recombination of photogenerated carriers. In this study, bismuth tungstate/hydrothermally treated Red phosphorus (Bi2WO6/HRP) heterojunction photocatalyst was prepare. The 1 %Bi2WO6/HRP composite exhibited strong photocatalytic performance, and the photodegradation rate of RhB after 12 min was as high as 98.9 %, which was much higher than that of HRP (53.0 %). Further characterization findings that the between HRP and Bi2WO6 formed heterojunction structure, which provided a pathway for the rapid transported of photogenerated carriers, allowing the effective separation of photogenerated electron-hole pairs, thus improved its photocatalytic activity.

TiO2/black phosphorus heterojunction modified by Ag nanoparticles for efficient photoelectrochemical water splitting

How to improve photon absorption, photoelectric conversion efficiency, and carrier separation and transfer efficiency is a huge challenge for promoting the efficiency of photoelectrochemical (PEC) water splitting. Herein, the black phosphorus nanosheets (BPNs) was assembled on the surface of TiO2 nanorods arrays (TiO2 NAs) through electrostatic attraction to form TiO2/BP heterojunction material. Meanwhile, Ag nanoparticles were successfully loaded on the surface of TiO2/BP heterojunction material to form Ag nanoparticles modified TiO2/BP heterojunction composite material. The TiO2/BP heterojunction modified by Ag nanoparticles nanostructures exhibited a remarkable enhancement in the PEC water splitting in comparison with the pristine TiO2. Photoelectrochemical performance at 1.23 V vs. RHE bias-potential under 100 mW cm−2 solar light illumination shows that synthesized Ag–TiO2/BP photoanode displaying the highest photocurrent density of 1.74 mA cm−2, which is practically 3.34 times higher than that of pristine TiO2 (0.52 mA cm−2), presenting a significantly improved PEC performance for water splitting. After 18 months, the photocurrent of synthesized Ag–TiO2/BP photoanode can still reach 1.63 mA cm−2, and the performance is stable. It demonstrated that the formation of heterojunction by electrostatic attraction of TiO2 and BP and then modification with Ag nanoparticles is an effective strategy for improving the PEC water splitting.

Anomalous Klein tunneling in two-dimensional black phosphorus heterojunctions.

We investigate the role of heterojunctions of few-layer black phosphorus (BP) with band gap inversion in governing the quantum transport behaviors. Numerical results show that in the armchair junction, electron tunneling probability occurs under approximately normal incidence with its magnitude T > 0.5. More interestingly, when different band gaps are taken into account on two sides of this junction, the maximum transmission appears away from the center of the valley, leading to the occurrence of anomalous Klein tunneling. Such a result tends to be independent of the width and height of the potential barrier. On the other hand, in the zigzag junction, electron transmission arises in a larger range of angles, and perfect electron transmission (T = 1.0) or reflection appears under specific band gap configurations. These findings provide a new understanding for the study of Klein tunneling and anomalous Klein tunneling based on tunable band gap BP or other two-dimensional Dirac semimetals.

Bi2MoO6/red phosphorus heterojunction for reducing Cr(VI) and mitigating Escherichia coli infection

Highly efficient visible-light-driven photocatalysts for removing diverse pollutants have become major topics of interest in wastewater treatment. In this study, the Bi2MoO6/HRP heterojunctions were designed by hydrothermal treatment using Bi2MoO6 and hydrothermally treated red phosphorus (HRP). The resulting 5%Bi2MoO6/HRP (with 5% mass fraction of Bi2MoO6) composite exhibited excellent photocatalytic performance for Cr(VI) reduction and Escherichia coli (E. coli) inactivation. The Cr(VI) photoreduction rate constant was 0.168 min−1, and the E.coli colony counts of 2.84 ​× ​108 ​CFU ​mL−1 was decreased to 1.6 ×107 CFU mL-1 after 30 ​min of visible light irradiation. Mechanistic investigation further revealed that photocatalytic performance was enhanced by the tight heterojunction between Bi2MoO6 and the HRP, thereby effectively promoting carrier transfer, and reducing the charge-carrier transfer resistance of composite catalyst. Meanwhile, cycling experiments presented outstanding photostability. This study exhibited that the highly efficient and stable 5%Bi2MoO6/HRP composite was potentially effective in treating toxic heavy metals and pathogenic bacteria for water treatment.

In-situ growth of metal phosphide-black phosphorus heterojunction for highly selective and efficient photocatalytic carbon dioxide conversion

Two-dimensional black phosphorus-based nanomaterials with distinct properties have emerged as fascinating semiconductor photocatalysts. In this work, metal phosphide (M-P: Co2P, Ni-P and Cu-P) in-situ growth on black phosphorus (BP) nanosheets is developed for photocatalytic carbon dioxide conversion. The M-P/BP heterojunction, especially Co2P/BP materials, show largely improved carbon dioxide capturing ability and charge separation efficiency. More importantly, the catalytic active Co in Co2P/BP can activate the adsorbed CO2 molecules and further boost the electron-hole separation process, which improves the photocatalytic activity for carbon dioxide reduction. The obtained Co2P/BP presented a photocatalytic CO production rate of 255.1 μmol/g∙h, which was almost two times higher than that of bulk BP (141.8 μmol/g∙h). This work shows that M-P/BP materials have high potential in photocatalytic CO2 reduction due to their high stability and performance.

Black phosphorus junctions and their electrical and optoelectronic applications

Black phosphorus (BP), an emerging two-dimensional material, is considered a promising candidate for next-generation electronic and optoelectronic devices due to in-plane anisotropy, high mobility, and direct bandgap. However, BP devices face challenges due to their limited stability, photo-response speed, and detection range. To enhance BP with powerful electrical and optical performance, the BP heterostructures can be created. In this review, the state-of-the-art heterostructures and their electrical and optoelectronic applications based on black phosphorus are discussed. Five parts introduce the performance of BP-based devices, including black phosphorus sandwich structure by hBN with better stability and higher mobility, black phosphorus homojunction by dual-gate structure for optical applications, black phosphorus heterojunction with other 2D materials for faster photo-detection, black phosphorus heterojunction integration with 3D bulk material, and BP via As-doping tunable bandgap enabling photo-detection up to 8.2 μm. Finally, we discuss the challenges and prospects for BP electrical and optical devices and applications.

High performance mid-wave infrared photodetector based on graphene/black phosphorus heterojunction

Black phosphorus (BP) as a promising candidate for mid-wave infrared (MWIR) detection has attracted much attention. However, the high-speed photoresponse at the MWIR is yet to be a challenge. In this paper, we report a BP-graphene heterostructure photodetector with fast photoresponse at MWIR range using molybdenum electrode as a contact to realizing a low Schottky barrier. The device exhibits a fast photoresponse in a broad-spectrum range from visible to MWIR (0.67–4.2 μm). A high photovoltaic responsivity up to 183 mA W−1 and EQE up to 35.6% were realized at the visible range of 0.637 μm light and respectively 7.9 mA W−1 and 0.31% at MWIR 3098 nm. The specific detectivity D* = 6.69 × 108 Jones is obtained at 1 mV bias under the illumination of the MWIR 4.25 μm in the ambient condition. Our work may open a new way to realizing fast MWIR photoresponse at the low light level.

Structural dependence of electrosynthesized cobalt phosphide/black phosphorus pre-catalyst for oxygen evolution in alkaline media.

The integration of black phosphorus (BP) with metal phosphides is known to produce high-performance electrocatalysts for oxygen evolution reduction (OER), although increased stability and prevention of the degradation of their lone pairs would be desirable improvements. In this work, cobalt phosphide (CoP)/BP heterostructures were electrochemically synthesized with a two-electrode system, where cobalt ions were generated in situ at a Co anode, and non-aggregated BP nanosheets (NSs) were exfoliated from the bulky BP cathode. With an electrolysis voltage of 30 V, the CoP/BP heterostructure exhibited a superior and stable OER performance (e.g., an overpotential of 300 mV at 10 mA cm-2, which is 41 mV lower than that obtained with a RuO2 catalyst). The CoOx formed in situ during the OER catalysis and remaining CoP synergistically contributed to the enhanced OER performance. The present strategy provides a new electrosynthetic method to prepare stable BP electrocatalysts and also further expands their electrochemical applications.

Synthesis and photocatalytic performance of MoS2/Polycrystalline black phosphorus heterojunction composite

As a promising catalyst for solar hydrogen production, black phosphorus (BP) has received widespread attention due to variable band gaps, high carrier mobility, and strong light absorption performance. Herein, we use MoS2 as a cocatalyst to synthesize BP/MoS2 catalyst with polycrystalline BP to improve photocatalytic performance under visible light irradiation. A small amount of MoS2 can reduce the recombination of electron-hole pairs in the composite, increase carrier transport efficiency, and then improve photocatalytic performance. As expected, the 10/0.5 ratio of BP/MoS2 catalyst exhibits the highest photocatalytic hydrogen evolution performance with a hydrogen evolution rate of 575.4 μmol h−1 g−1, which is 2.5 times of pure BP. Based on the results above, a simple method is provided to synthesize low-cost black phosphorus-based photocatalysts.

Complementary Trilayer–Bulk Black Phosphorus Heterojunction Tunnel Field-Effect Transistor with Subthermionic Subthreshold Swing

Reductions in transistor size have improved functionality of transistors and lowered costs of electronic processors. However, as transistors decrease in size, quantum tunneling causes increased lea...

Three-dimensional bismuth oxide/red phosphorus heterojunction composite with enhanced photoreduction activity

In order to solve the problems of easy recombination of carriers and low efficiency of photocatalysis in red phosphorus photocatalyst, Bi2O3/HRP heterostructure composite photocatalyst was prepared by hydrothermal method. Cr(VI) was selected as the model contaminant to investigate the photoreduction activity of the photocatalysts. The experimental results revealed that the composite photocatalyst obtained at 3% Bi2O3 mass fraction (3%Bi2O3/HRP) exhibited the strongest photoreduction ability, and its rate constant was 14.9 and 50 times that of pure HRP and Bi2O3. The photoelectric conversion efficiency of the photocatalyst improved, which was illuminated by the high current density (16.7 and 42 times higher than that of HRP and Bi2O3) and the heterogeneous interface that facilitated charge transfer and separation. On the basis of the matched band structure of Bi2O3 and HRP, Bi2O3 with wide band gap (Eg) is introduced into HRP with narrow Eg to form a heterojunction structure, which provides an effective strategy to promote space charge separation and transfer.

2D tellurene/black phosphorus heterojunctions based broadband nonlinear saturable absorber

Abstract Two-dimensional (2D) mono-elemental materials (Xenes) show remarkable potential in the fields of fundamental science and technology, have been regarded as a wide range of building blocks for electronic technologies due to their unique chemical, physical, electrical, and optical properties. Here, 2D tellurene/black phosphorus (Te/BP) heterojunctions are successfully fabricated through liquid-phase exfoliation (LPE) method. Their nonlinear optical absorption properties at 1.0, 2.0, and 2.8 μm have been studied by an open-aperture Z-scan method. The results revealed the excellent broadband saturable absorption responses of the prepared BP/Te heterojunctions, which are further confirmed by using them as saturable absorbers (SAs) for passively Q-switched all-solid-state lasers operating at 1.0, 2.0, and 2.8 μm, respectively. In particular, 1.04 μm continuous-wave (CW) mode-locked lasers with a pulse width of 404 fs is realized for the first time, to our best knowledge. Our work indicates that 2D Xenes especially 2D Xenes based heterojunctions have great potential in the fields of pulsed laser generation/modulation and other optoelectronic and photonic devices.

First-principles study on photovoltaic properties of 2D Cs2PbI4-black phosphorus heterojunctions

Both 2D perovskite Cs2PbI4 and phosphorus are significant optoelectronic semiconductor materials, the optical-electrical characters between both contact interfaces are interesting topics. In present work, we demonstrate comparative investigation of optoelectronic properties for two kinds of electrical contact interfaces. i.e. Pb–I and Cs–I interfaces with black phosphorus contacts. The carrier transport, charge transferring and optical properties for both cases are investigated by using first principle calculation. Both contact interfaces exhibit type II band alignment with direct band gap. Charge carrier migration from Cs–I interface to black phosphorus is more strong than that of Pb–I interface by considering differential charge density and bader charge between distinct electrical contact interfaces. Besides, electron–hole effective masses of heterojunctions for both cases along different direction are investigated. Optical absorption coefficients of both cases are compared with those of free-standing Cs2PbI4 and black phosphorus in the visible spectrum. We systematically compared advantages and disadvantages of two kinds of contact interfaces for photovoltaic application, and the results reveal interfacial engineering of 2D heterojunction plays a important role in tuning optoelectronic properties.