Simple Hot-injection Research Articles

Ni3C/Ni3S2 Heterojunction Electrocatalyst for Efficient Methanol Oxidation via Dual Anion Co-modulation Strategy.

Enhancing active states on the catalyst surface by modulating the adsorption-desorption properties of reactant species is crucial to optimizing the electrocatalytic activity of transition metal-based nanostructured materials. In this work, an efficient optimization strategy is proposed by co-modulating the dual anions (C and S) in Ni3C/Ni3S2, the heterostructured electrocatalyst, which is prepared via a simple hot-injection method. The presence of Ni3C/Ni3S2 heterojunctions accelerates the charge carrier transfer and promotes the generation of active sites, enabling the heterostructured electrocatalyst to achieve current densities of 10/100mA cm-2 at 1.37V/1.53V. The Faradaic efficiencies for formate production coupled with hydrogen evolution approach 100%, accompanied with a stability record of 350h. Additionally, operando electrochemical impedance spectroscopy (EIS), in situ Raman spectroscopy, and density functional theory (DFT) calculations further demonstrate that the creation of Ni3C/Ni3S2 heterointerfaces originating from dual anions' (C and S) differentiation is effective in adjusting the d-band center of active Ni atoms, promoting the generation of active sites, as well as optimizing the adsorption and desorption of reaction intermediates. This dual anions co-modulation strategy to stable heterostructure provides a general route for constructing high-performance transition metal-based electrocatalysts.

Improvement of optical properties of lead-free double perovskite Cs2AgInCl6 nanocrystals through Bi ion alloying

Lead-free double perovskite nanocrystals (NCs) have garnered significant attention due to their non-toxicity and excellent stability, offering vast potential applications in the field of optoelectronics. They are considered promising substitutes for lead-based perovskite NCs. Herein, we successfully synthesized monodisperse, uniformly sized, cubic-shaped Cs2AgIn1-xBixCl6 (0 ≤ x ≤ 1) NCs via a simple hot injection approach. The Cs2AgInCl6 NCs exhibit a lower photoluminescence quantum yield (PLQY) of 3.9 % due to the presence of parity-forbidden transitions. However, with the introduction of Bi3+ alloying, the parity-forbidden transitions are broken, transforming into direct transitions allowed by parity. This transformation leads to efficient bright yellow emission, with the highest PLQY reaching up to 31.6 % (Cs2AgIn0.90Bi0.10Cl6 NCs). Adjusting the Bi3+ alloying concentration allows tuning the NCs band gap from 3.62 eV to 2.88 eV, and the exciton lifetime can be extended from 5.99 ns to 24.88 ns. Temperature-dependent photoluminescence spectra and density functional theory calculations indicate that Bi3+ alloying increases the exciton binding energy, weakens the electron-phonon coupling, and breaks parity-forbidden transitions. Moreover, Cs2AgIn0.90Bi0.10Cl6 NCs display outstanding stability under ambient conditions, laying a solid foundation for their applications in optoelectronics. The results of this study open a new pathway to enhance the optical performance of lead-free double perovskite nanomaterials.

Quaternary nanorods: promising versatile agents for cancer therapy, antimicrobial strategies and free radical neutralization

Cu2XSnS4 (CXTS; X: Zn, Mn or Co) nanorods (NRs) were prepared by a simple hot-injection method and their cytotoxic activities on human breast adenocarcinoma (MCF-7), metastatic melanoma (451Lu) and embryonic kidney (HEK-293) cell lines were investigated for the first time. The antibacterial activities of these nanoparticles on both gram-positive (S. aureus) and gram-negative (E. coli) pathogenic bacteria as well as their DPPH (2,2-diphenyl-1- picrylhydrazyl) scavenging activities were evaluated. The structural characterizations show that the obtained nanoparticles have the same crystal structure and are shaped as nanorods with an average 10–40 nm edge length. The data obtained in cytotoxicity studies revealed that the synthesized CXTS NRs have a significant inhibition effect, especially on cancer cell lines (MCF-7 and 451Lu), in a dose-dependent manner over a period of 24 h, demonstrating their potential for use as anticancer agents. In addition, the findings indicate that the synthesized nanorods possess strong antibacterial properties against the pathogenic microorganisms tested and display a marked antioxidant effect through efficient elimination of DPPH activity. This comprehensive study sheds light on the creation and development of CXTS NRs as promising versatile agents in various biomedical and environmental applications such as cancer therapy, antimicrobial strategies and the neutralization of free radicals.

High-Performance Paper-Based Thermoelectric Generator from Cu2SnS3 Nanocubes and Bulk-Traced Bismuth.

Flexible paper-based thermoelectric generators (PTEGs) have drawn significant interest in recent years due to their various advantages such as flexibility, adaptability, environment friendliness, low cost, and easy fabrication process. However, the reported PTEG's output performance still lags behind the performance of other flexible devices as it is not so easy to obtain a compact film on a paper-based substrate with desirable power output with the standard thermoelectric (TE) materials that have been previously utilized. In this direction, Cu2SnS3 (CTS), an earth-abundant, ternary sulfide, can be a good choice p-type semiconductor, when paired with a suitable n-type TE material. In this article, CTS nanocubes are synthesized via a simple hot injection method and a thick film device on emery paper was prepared and optimized. Furthermore, a flexible, 20-pair PTEG is fabricated with p-type CTS legs and traced and pressed n-type bismuth legs assembled using Kapton tape that produced a significantly high output power of 2.18 μW (output power density ∼0.85 nW cm-2 K-1) for a temperature gradient of ΔT = 80 K. The TE properties are also supported by finite element simulation. The bending test conducted for the PTEG suggests device stability for up to 800 cycles with <0.05% change in the internal resistance. A proof-of-concept field-based demonstration for energy harvesting from waste heat of a motorbike exhaust is shown recovering an output power of ∼42 nW for ΔT = 20 K, corroborating the experimental and theoretical results.

Zn doping induced optimization of optical and dielectric characteristics of CuInSe2 nanosheets for optoelectronic device applications

The ternary chalcopyrite CuInSe2 (CIS) has recently gained significant attention due to its potential applications in various optoelectronics and photonics devices. Here, the CIS nanosheets with different Zn doping content were synthesized by a simple hot injection method. The undoped CIS showed pure crystallinity, while Zn incorporation led to the enhancement of the amorphous nature inside the matrix. A shift in the diffraction pattern and Raman vibrational bands with varying Zn content suggests the doping-induced structural rearrangements inside the system. Morphological study deliberates the transit from clean proper CIS nanosheets to pigmented patterns due to doping. The Zn doping in the CIS lattice causes the insertion of the more intermediate levels within the band gap that enhances the optical absorption. The variation of the absorption edges with doping content tends to decrease the optical band gap by creating more disorder and defects in between the gap region. Broad absorbance over visible and NIR region and reduction in Eg favours in the application of an absorber layers in solar cells. Broad photoluminescence emission is observed for all the cases with 514 nm excitation. Each spectrum is comprised of four component peaks corresponding to the transition between different intermediate levels. The dielectric behaviour as a function of frequency and temperature was investigated, and the results showed improved conductivity with reduced dielectric loss. The dielectric constant and tangent loss decreased with frequency and improved with increasing temperature. The improvement of AC conductivity with temperature concludes the increase in the mobility of charge carriers that are responsible for hopping and electronic polarization. The observed optical and dielectric properties are quite suitable for various photonics, memory devices. electro-optic devices and their applications.

Incorporation sodium ions into monodisperse lead-free double perovskite Cs2AgBiCl6 nanocrystals to improve optical properties

Lead-free double perovskite nanocrystals (NCs) have emerged as a promising candidate in the optical field, owing to their non-toxic, good moist heat and chemical stability. However, their poor optical properties limited their application. To improve the optical properties of lead-free double perovskite NCs, metal ion doping or alloying had been suggested as a promising strategy. Here, we prepared monodisperse, uniformly sized, cubic morphology of Cs2AgBiCl6 NCs with different Na+ incorporation amounts via a simple hot-injection method. The Na+ incorporation broke the parity-forbidden transition by reducing the inversion symmetry of the electron wave function at the Ag site, which changed the parity of the self-trapped exciton wave function and thus allowed radiative recombination. As a result, the photoluminescence quantum yield (PLQY) of Na+-alloyed Cs2AgBiCl6 NCs (12.1%) was higher than that of Cs2AgBiCl6 NCs (2.4%), and the exciton lifetime of Na+-alloyed Cs2AgBiCl6 NCs increased to 36.98 ns from 17.58 ns for Cs2AgBiCl6 NCs. By adjusting the amount of Na+ incorporation, the band gap of Cs2AgBiCl6 NCs can be significantly tuned from ∼2.90 eV to ∼3.50 eV. Furthermore, the temperature-dependent photoluminescence spectra indicated that the Na+-alloyed Cs2AgBiCl6 NCs possessed higher longitudinal optical phonon energy and exciton binding energy compared to Cs2AgBiCl6 NCs. This suggested that there were strong exciton-phonon interactions during exciton recombination, a reduced probability of non-radiative processes, and excellent thermal stability. It offers a promising strategy for improving the optical properties of lead-free double perovskite NCs, and have the potential to replace traditional lead halide perovskite NCs in future optoelectronic applications.

Lead-Free Cesium Thulium Halide Perovskite Microcrystals for Near Ultraviolet Luminescence.

Lead halide perovskites attract tremendous research attention due to excellent optoelectronic properties. However, realizing efficient near ultraviolet (NUV) luminescence with these materials is still a big challenge. Herein, a novel rare-earth perovskite cesium thulium chloride (CsTmCl3 ) with high crystallinity has been synthesized via a simple hot-injection method. The obtained CsTmCl3 microcrystals have a size distribution of around 1-5µm, and demonstrate a highly efficient NUV emission at 337nm with a full width at half maximum (FWHM) of 68nm. The determined band gap of CsTmCl3 microcrystals is ≈3.92eV, which is supported by theoretical calculations. Moreover, a high photoluminescence quantum yield (PLQY) of up to 12% in NUV region has been achieved in such a lead-free perovskite. The findings suggest that CsTmCl3 perovskite microcrystal is a promising low-toxic material for applications in NUV optoelectronic devices.

An ultrasmall PVP-Fe-Cu-Ni-S nano-agent for synergistic cancer therapy through triggering ferroptosis and autophagy.

Photothermal therapy (PTT) is an emerging field where photothermal agents could convert visible or near-infrared (NIR) radiation into heat to kill tumor cells. However, the low photothermal conversion efficiency of photothermal agents and their limited antitumor activities hinder the development of these agents into monotherapies for cancer. Herein, we have fabricated an ultrasmall polyvinylpyrrolidone (PVP)-Fe-Cu-Ni-S (PVP-NP) nano-agent via a simple hot injection method with excellent photothermal conversion efficiency (∼96%). Photothermal therapy with this nano-agent effectively inhibits tumor growth without apparent toxic side-effects. Mechanistically, our results demonstrated that, after NIR irradiation, PVP-NPs can induce ROS/singlet oxygen generation, decrease the mitochondrial membrane potential, release extracellular Fe2+, and consume glutathione, triggering autophagy and ferroptosis of cancer cells. Moreover, PVP-NPs exhibit excellent contrast enhancement according to magnetic resonance imaging (MRI) analysis. In summary, PVP-NPs have a high photothermal conversion efficiency and can be applied for MRI-guided synergistic photothermal/photodynamic/chemodynamic cancer therapy, resolving the bottleneck of existing phototherapeutic agents.

Thiophene Derivatives as Ligands for Highly Luminescent and Stable Manganese-Doped CsPbCl3 Nanocrystals.

Ligands on the surface of perovskite nanocrystals are important to stabilize the nanocrystal structure. However, the research of ligands on Mn2+ ion-doped CsPbCl3 nanocrystals (Mn: CsPbCl3 NCs), a promising candidate family for the lightning community, is relatively rare. Here, we demonstrate a new ligand modification strategy for preparing high-quality Mn: CsPbCl3 NCs by a simple hot-injection method. Thiophene derivative, for the first time, is applied as ligands for perovskite nanocrystals. The new ligands of thiophene derivatives passivate defects on the surface of NCs and enhance optical properties, originating from the sulfur in thiophene additives binding to the uncoordinated lead ions. The photoluminescence quantum yield of the modified Mn: CsPbCl3 NCs is 93% in comparison with 46% of the pristine counterparts, whose value is the highest to date for ligand-modified Mn: CsPbCl3 NCs. Meanwhile, the thermal, storage, and purification stability are also significantly improved. The performance of related LEDs is also investigated.

Carbon nanotube supported thiospinel quantum dots as counter electrodes for dye sensitized solar cells

In the current study, sulfide based ternary and quaternary thiospinel nanocrystals were synthesized by using a simple hot injection method and used as catalyst instead of Pt in a DSSCs application for the first time. CuNiCoS4, CuCo5S8, and CuCo2S4 as thiospinel nanocrystals have been synthesized in crystalline structure, single phase, nearly stoichiometric, and having narrow size distribution below 10 nm. Comparative studies showed that, Carbon Nanotube (CNT)-CuCo2S4 based DSSCs yielded the most favorable results as a potential counter electrode showing very similar power conversion efficiency (ƞ = 4.99%) in comparison with Pt based DSSCs produced under identical conditions. Therefore, this study implies that the thiospinel nanocrystals and their CNT supported composites can be proposed as novel counter electrode materials for low-cost platinum-free solar cells.

Cu 2 AgInS 2 Se 2 quantum dots sensitized porous TiO 2 nanofibers as a photoanode for high‐performance quantum dot sensitized solar cell

Cu2AgInS2Se2 alloyed quantum dots are synthesized through a simple hot injection method. Its tetragonal structure and crystallite size are determined by using X-ray diffraction analysis. Its optical properties are observed by using Ultraviolet-Vis absorption and PL emission spectroscopies. The oxidation state and elemental composition of Cu2AgInS2Se2 quantum dots are confirmed by X-ray photoelectron spectroscope analysis and energy dispersive X-ray analysis, respectively. The optical bandgap of the synthesized quantum dots is measured to be 1.29 eV. The synthesized Cu2AgInS2Se2 quantum dots are sensitized onto the porous TiO2 nanofibers (CAISSe/P-TiO2) and its morphological and optical properties are examined. The quantum dot sensitized solar cell is assembled using CAISSe/P-TiO2, polysulfide and Cu2S as the photoanode, electrolyte and the counter electrode exhibited photoconversion efficiency (PCE) of 5.87%, which is significantly higher than that assembled using Cu2AgInSe4 (4.21%) and Cu2AgInS4 (4.89%) quantum dots sensitized porous TiO2 NFs as the photoanodes.

Effect of Annealing on Innovative CsPbI3-QDs Doped Perovskite Thin Films

In this study, a simple hot-injection method to synthesize high-quality inorganic perovskite cesium lead iodide (CsPbI3) quantum-dots (QDs) was demonstrated. Adding CsPbI3 QDs into the organic perovskite methylamine lead triiodide (CH3NH3PbI3) to form a composite perovskite film, annealed by different temperatures, was found to be effectively enhanced by the perovskite crystallization. The intensity of the preferred peak (110) of MAPbI3 was enhanced by increasing the size of the crystal and reducing the cluster crystal. The densest film can be found at annealing temperature of 140 °C. The full width half maximum of MAPbI3 and CsPbI3 was analyzed through XRD peak fitting. This was a huge breakthrough for QDs doped perovskite films.

The hole transporting behaviour of Cu2AgInS4 and Cu2AgInSe4 for a carbon electrode-based perovskite solar cell

In this work, quaternary Cu2AgInS4 (CAIS) and Cu2AgInSe4 (CAISe) nanoparticles (NPs) were synthesised by a simple hot injection method and their photovoltaic behaviour were studied in detail for PSC.

Cu2AgInSe4 QDs sensitized electrospun porous TiO2 nanofibers as an efficient photoanode for quantum dot sensitized solar cells

To obtain an efficient quantum dot sensitized solar cell (QDSC), a less toxic quaternary Cu2AgInSe4 QDs with 4.8 nm in size are synthesized by a simple hot injection method. The crystallite size and tetragonal structure are confirmed by XRD and HR-TEM analysis. Energy-dispersive X-ray spectroscopy analysis reveals that the atomic ratio of Cu: Ag: In: Se in the Cu2AgInSe4 QDs is 1.98:1.0:1.03:3.86. The oxidation state of the elements composed in Cu2AgInSe4 QDs is confirmed by XPS studies. Optical properties are studied from the UV–Vis–NIR absorption spectrum and photoluminescence emission spectrum. The porous TiO2 nanofibers (P-TiO2 NFs) are prepared from the conventional electrospun TiO2 NFs followed by the solvosonication process. The FE-SEM analysis is confirmed the porous texture of the TiO2 NFs. The bandgap of the Cu2AgInSe4 QDs and TiO2 NFs are determined from the Tauc plot and it was found to be 1.93 eV and 3.19 eV, respectively. QDSC is assembled using Cu2S counter electrode, polysulfide redox couple electrolyte and Cu2AgInSe4 QDs sensitized P-TiO2 NFs photoanode. The photoconversion efficiency (PCE) of the assembled QDSC is found to be 4.24%.

Colloidal synthesis of lead-free all-inorganic Cs3Sb2BrxI9-x nanocrystals

Environment-friendly lead-free perovskite nanocrystals (NCs) are highly desirable in terms of optoelectronic applications. Reported herein is the synthesis of perovskite-related Cs3Sb2Br9 NCs through a simple hot-injection approach. The morphologies and optical properties of NCs were controlled and optimized by varying the reaction temperature, time, and volume of surface ligands. Meanwhile, the Cs3Sb2Br9 NCs showed bandgap emission in the blue region centered at 470 nm, and 63 nm full width at half maximum (FWHM). In addition, the Cs3Sb2Br9 NCs displayed high stability when immersed in a polar solvent like ethanol. It was also found that the bandgaps of the Cs3Sb2BrxI9-x NCs could be adjusted by regulating the composition of halogen.

Rare-Earth-Element-Ytterbium-Substituted Lead-Free Inorganic Perovskite Nanocrystals for Optoelectronic Applications.

Lead-(Pb-) halide perovskite nanocrystals (NCs) are interesting nanomaterials due to their excellent optical properties, such as narrow-band emission, high photoluminescence (PL) efficiency, and wide color gamut. However, these NCs have several critical problems, such as the high toxicity of Pb, its tendency to accumulate in the human body, and phase instability. Although Pb-free metal (Bi, Sn, etc.) halide perovskite NCs have recently been reported as possible alternatives, they exhibit poor optical and electrical properties as well as abundant intrinsic defect sites. For the first time, the synthesis and optical characterization of cesium ytterbium triiodide (CsYbI3 ) cubic perovskite NCs with highly uniform size distribution and high crystallinity using a simple hot-injection method are reported. Strong excitation-independent emission and high quantum yields for the prepared NCs are verified using photoluminescence measurements. Furthermore, these CsYbI3 NCs exhibit potential for use in organic-inorganic hybrid photodetectors as a photoactive layer. The as-prepared samples exhibit clear on-off switching behavior as well as high photoresponsivity (2.4 × 103 A W-1 ) and external quantum efficiency (EQE, 5.8 × 105 %) due to effective exciton dissociation and charge transport. These results suggest that CsYbI3 NCs offer tremendous opportunities in electronic and optoelectronic applications, such as chemical sensors, light emitting diodes (LEDs), and energy conversion and storage devices.

In situ growth of Co9S8 nanocrystals on reduced graphene oxide for the enhanced catalytic performance of dye-sensitized solar cell

The counter electrode material of dye-sensitized solar cells (DSSCs) with excellent catalytic activity and fast electron transfer ability could effectively improve the overall photoelectrical conversion efficiency (PCE). In this work, monodispersed Co9S8 nanocrystals (NCs) were in situ grown on the surface of the reduced graphene oxide (RGO) through a simple hot-injection method. Due to the confinement of organic ligand oleylamine, the Co9S8 NCs with the size of ca. 8 nm were mainly dispersed on the surface of RGO (Co9S8/RGO). The Co9S8/RGO composite with the optimal contents (RGO contents of 44.4 wt%) was prepared by controlling the amount of graphene oxide (GO) added, which possessed the optimal catalytic active site numbers and electron transfer ability as it showed a higher PCE of 7.31%. It was higher than that of the solo Co9S8 NCs and comparable to that of the Pt (7.72%). The electrochemical characteristics (cyclic voltammetry, Tafel polarization curve, and electrochemical impedance spectroscopy) confirmed their excellent electrocatalytic activity towards I3−/I− redox reduction. Furthermore, the calculations based on the density functional theory (DFT) revealed that the absorption energy of I3− on the Co site at the interface of Co9S8/RGO composite was −1.881 eV, which was higher than that of solo Co9S8 NCs (−1.078 eV). So, Co atoms in the Co9S8/RGO interface was the predominant catalytic active center for the I3− reduction. This in situ growth strategy provided a new strategy for the preparation of electrocatalytic materials.

Donor-π-acceptor dye-sensitized photoelectrochemical and photocatalytic hydrogen evolution by using Cu2WS4 co-catalyst

Photoelectrochemical and photocatalytic hydrogen evolution reaction (HER) have been investigated by using metal free donor-acceptor (D-A) and donor-π-acceptor (D-π-A) dyes, which are abbreviated as MC-32 and MC-048, respectively, sensitized TiO2 as a photocatalyst with or without Cu2WS4 co-catalyst. This co-catalyst is synthesized by a low-cost and simple hot injection method, under visible light illumination. The photoactivities of these dyes have been clarified according to their structural, optical and electrochemical properties. Photocatalytic activities have been slightly increased when added the Cu2WS4 co-catalyst (dye/TiO2/Cu2WS4). This catalytic activity is also compared to that of noble metal Pt (dye/TiO2/Pt). It has been found that 121 μmolg−1h−1, 179 μmolg−1h−1, 348 μmolg−1h−1, 212 μmolg−1h−1, 422 μmolg−1h−1 and 1139 μmolg−1h−1 hydrogen have been evolved by using MC-32/TiO2, MC-32/TiO2/Cu2WS4, MC-32/TiO2/Pt, MC-048/TiO2, MC-048/TiO2/Cu2WS4 and MC-048/TiO2/Pt, respectively.

Tetrahedrite (Cu12Sb4S13) Ternary Inorganic Hole Conductor for Ambient Processed Stable Perovskite Solar Cells

The hole transport layer (HTL) in a solar cell is a key component for the optimization of photon to electron conversion efficiency and long-term device stability. So far, organic hole transport (HT) materials have been extensively used in mesoscopic perovskite (n–i–p) solar cells for achieving high efficiency. Generally, organic hole transporters are expensive and exhibit low chemical stability. This often results in rapid degradation in the photon to electron conversion efficiencies. In this report, copper antimony sulfide (CAS, Cu12Sb4S13) tetrahedrite crystal phase nanoparticles capped with organic ligands are synthesized using a simple hot injection method. The ternary semiconductor nanoparticles exhibit high carrier concentration (3.4 × 1018 cm–3) and electrical conductivity (0.043 Ω cm) with respect to the conventionally used organic HT, e.g., spiro-OMeTAD. Additionally, appropriate conduction band and valence band positions in the CAS nanoparticles assist in efficient separation of the photogenerated holes from the perovskite materials and block the electrons from moving transport toward the counter metal contact. Incorporation of CAS in the MAPbI3 perovskite solar cell as an HTL, assembled using an ambient fabrication process, achieves a power conversion efficiency of approximately 6.5%. The efficiency degradation studied under controlled humidity (<70%) conditions exhibited a slower rate of decrease for the MAPbI3–CAS (85% and 50% on the 4th and 15th day) compared to the MAPbI3-spiro solar cell (10% on the fourth day). The chemical stability and solar cell performance are attributed to the synergetic effect of crystal phase stability and hydrophobic nature of the organic ligand capped CAS HTL layer. This leads to high moisture resistance and nullifies the need for an additional encapsulation layer as demonstrated in reported literature studies.

Hexagonally Shaped Two-Dimensional Tin(II)sulfide Nanosheets: Growth Model and Controlled Structure Formation

Tin(II)sulfide (SnS) is a well-known representative of IV–VI semiconducting materials with a layered crystal structure. SnS is of great interest due to its low toxicity and its optical and electrical properties. Here, we report on the first colloidal synthesis of hexagonally shaped single crystalline SnS nanosheets with tunable dimensions. The SnS nanosheets crystallize in the thermodynamically preferred orthorhombic α-phase. High-resolution transmission electron microscopy and electron diffraction were executed in order to determine the growth direction of these hexagonally formed nanosheets. The simple hot-injection approach comprises the injection of a sulfur-oleylamine complex into a hot solution mixture containing oleylamine, oleic acid, tin(II)chloride, and hexamethyldisilazane (HMDS). HMDS is an essential chemical for many colloidal syntheses of two-dimensional nanosheets, but its function is not well described until now. Here, we elucidate the function of HMDS as an essential additive for the form...