Additive-Assisted Hydrothermal Growth Enabling Defect Passivation and Void Remedy in Antimony Selenosulfide Solar Cells.

Antimony selenosulfide (Sb2(S,Se)3) has recently emerged as a promising light-absorbing material, attributed to its tunable photovoltaic properties, low toxicity, and robust environmental stability. However, despite these advantages, the current record efficiency for Sb2(S,Se)3 solar cells significantly lags behind their Shockley-Queisser limit, especially when compared to other well-established chalcogenide-based thin-film solar cells, such as CdTe and Cu(In,Ga)Se2. This underperformance primarily arises from the formation of unfavorable defects, predominately located at deep energy levels, which act as recombination centers, thereby limiting the potential for performance enhancement in Sb2(S,Se)3 solar cells. Specifically, deep-level defects, such as sulfur vacancy (VS), have a lower formation energy, leading to severe non-radiative recombination and compromising device performance. To address this challenge, thioacetamide (TA), a sulfur-containing additive is introduced, into the precursor solution for the hydrothermal deposition of Sb2(S,Se)3. This results indicate that the incorporation of TA helps in passivating deep-level defects such as sulfur vacancies and in suppressing the formation of large voids within the Sb2(S,Se)3 absorber. Consequently, Sb2(S,Se)3 solar cells, with reduced carrier recombination and improved film quality, achieved a power conversion efficiency of 9.04%, with notable improvements in open-circuit voltage and fill factor. This work provides deeper insights into the passivation of deep-level donor-like VS defects through the incorporation of a sulfur-containing additive, highlighting pathways to enhance the photovoltaic performance of Sb2(S,Se)3 solar cells.

Hydrothermal deposition synthesis of dual-mode luminescent material GdVO4 :Eu3+ /carbon dots with optimal luminescence and its application in anti-counterfeiting.

To obtain optimal luminescence, 0.12 g of GdVO4 :3%Eu3+ nanocrystals (NCs) and different volumes of nitrogen-doped carbon dots (N-CDs) crude solution were used as precursors, and the composite synthesized using the hydrothermal deposition method showed optimal luminescence when 11 ml (2.45 mmol) crude solution was used. In addition, similar composites with the same molar ratio as GVE/cCDs(11) were also prepared with the hydrothermal and physical mixing processes. Based on the test results of XRD, XPS, and PL spectra, for the composite GVE/cCDs(11), the highest (lowest) peak intensity of the C-C/C=C (C=O/C=N) bond, which was 1.18 (0.75) times that of GVE/cCDs-m, indicated most N-CDs deposition and led to their highest emission intensity under 365 nm excitation, although nitrogen atoms in the composite were shed slightly during the deposition process. Finally, as can be seen from the patterns designed for security applications that the optimally luminescent composite is one of the most promising candidates in the anti-counterfeiting field.

Efficient In Situ Sulfuration Process in Hydrothermally Deposited Sb2S3 Absorber Layers.

Sulfuration plays a decisive role in enhancing crystal growth and passivate defects in the fabrication of high-efficiency metal-sulfide solar cells. However, the traditional sulfuration process always suffers from high-price professional equipment, tedious processes, low activity of S, or high toxicity of H2S. Here, we develop a desired in situ sulfuration by introducing tartaric acid additive into the hydrothermal deposition process of Sb2S3. Tartaric acid, sodium thiosulfate, and potassium antimony tartaric can form Sb2Sx-contained (x > 3) as-prepared films. Encouragingly, the annealing becomes an inspiring in situ sulfuration process, which can obtain a more compact absorber layer. In addition, the crystallinity and defect property of the Sb2S3 film are also improved significantly. Finally, we achieve a high-performance Sb2S3 solar cell with a power conversion efficiency of 6.31%, which shows an encouraging enhancement of ∼15% compared with the traditional hydrothermal process. This study provides an innovative way to prepare high-efficiency Sb2S3 solar cells and provides a desirable guide to realize the in situ sulfuration process.

pH Controlled Nanostructure and Optical Properties of ZnO and Al-Doped ZnO Nanorod Arrays Grown by Microwave-Assisted Hydrothermal Method.

The low-temperature microwave-assisted hydrothermal method was used to successfully grow pure and Al-doped ZnO (AZO) nanorod (NR) arrays on glass substrates. The combined effects of doping and pH on the structural properties, surface chemistry, and optical properties of all samples were investigated. Thermodynamic-based simulations of the growth solution were performed and a growth mechanism, that considers the effects of both the pH and Al-doping, is proposed, and discussed. Tuning the solution pH is key parameter to grow well-aligned, single crystal, highly packed, and high aspect ratio nanorod arrays. Moreover, the optical absorption in the visible range is enhanced by controlling the pH value. The PL spectra reveal a shift of the main radiative emission from the band-to-band into a transition involving deep defect levels of Zinc interstitial Zni. This shift is caused by an enhancement of the non-radiative components (phonon relaxation) at high pH values. The production of well-ordered ZnO and AZO nanorod arrays with visible-active absorption/emission centers would increase their potential use in various applications.

Effect of Hydrothermal Method Temperature on the Spherical Flowerlike Nanostructures NiCo(OH)4-NiO.

NiCo(OH)4-NiO composite electrode materials were prepared using hydrothermal deposition and electrophoretic deposition. NiCo(OH)4 is spherical and flowerlike, composed of nanosheets, and NiO is deposited on the surface of NiCo(OH)4 in the form of nanorods. NiCo(OH)4 has a large specific surface area and can provide more active sites. Synergistic action with NiO deposits on the surface can provide a higher specific capacitance. In order to study the influence of hydrothermal reaction temperature on the properties of NiCo(OH)4, the prepared materials of NiCo(OH)4-NiO, the hydrothermal reaction temperatures of 70 °C, 90 °C, 100 °C, and 110 °C were used for comparison. The results showed that the NiCo(OH)4-NiO-90 specific capacitance of the prepared electrode material at its maximum when the hydrothermal reaction temperature is 90 °C. The specific capacitance of the NiCo(OH)4-NiO-90 reaches 2129 F g-1 at the current density of 1 A g-1 and remains 84% after 1000 charge-discharge cycles.

Synergistic fabrication of micro-nano bioactive ceramic-optimized polymer scaffolds for bone tissue engineering by in situ hydrothermal deposition and selective laser sintering.

Biodegradable three-dimensional porous scaffolds have attracted increasing attention as promising implants in bone tissue engineering. The micro/nano surface structure of scaffolds has also attracted significant attention due to its significant effects on scaffold physicochemical properties and cell behavior. Herein, polycaprolactone-polylactic acid-nano hydroxyapatite (PCL-PLA-nHA) ternary composite porous scaffolds with micro-nano bioactive surfaces were fabricated by combining selective laser sintering (SLS) and in situ hydrothermal deposition processes. The mechanical properties, micro/nano surface morphology, wettability, and cytocompatibility of the composite scaffolds were systematically evaluated. The results showed that the blending of PLA enhanced the compressive and tensile strength of the PCL scaffold, while also enhancing the modulus, but did not significantly change the tensile elongation. Moreover, the blending of PLA changed the fracture mode of the scaffold from ductile to brittle and its fracture mechanism was proposed. In addition, the formation mechanism of micro-nano surfaces under hydrothermal conditions was also summarized according to the micro-morphology of scaffolds. Besides, the PCL-PLA-nHA scaffold exhibited higher mineralization ability, excellent wettability, and better cytocompatibility, indicating its remarkable promise in bone tissue engineering applications.

Zn(O,S) Buffer Layer for in Situ Hydrothermal Sb2S3 Planar Solar Cells.

Hydrothermal deposition is emerging as a highly potential route for antimony-based solar cells, in which the Sb2(S,Se)3 is typically in situ grown on a common toxic CdS buffer layer. The narrow band gap of CdS causes a considerable absorption in the short-wavelength region and then lowers the current density of the device. Herein, TiO2 is first evaluated as an alternative Cd-free buffer layer for hydrothermally derived Sb2S3 solar cells. But it suffers from a severely inhomogeneous Sb2S3 coverage, which is effectively eliminated by inserting a Zn(O,S) layer. The surface atom of sulfur in Zn(O,S) uniquely provides a chemical bridge to enable the quasi-epitaxial deposition of Sb2S3 thin film, confirming by both morphology and binding energy analysis using DFT. Then the results of the first-principles calculations also show that Zn(O,S)/Sb2S3 has a more stable structure than TiO2/Sb2S3. The resultant perfect Zn(O,S)/Sb2S3 junction, with a suitable band alignment and excellent interface contact, delivers a remarkably enhanced JSC and VOC for Sb2S3 solar cells. The device efficiency with the TiO2/Zn(O,S) buffer layer boosts from 0.54% to 3.70% compared with the counterpart of TiO2, which has a champion efficiency of Cd-free Sb2S3 solar cells with a structure of ITO/TiO2/Zn(O,S)/Sb2S3/Carbon/Ag by in situ hydrothermal deposition. This work provides a guideline for the hydrothermal deposition of antimony-based films upon a nontoxic buffer layer.

Direct Hydrothermal Deposition of Antimony Triselenide Films for Efficient Planar Heterojunction Solar Cells.

Antimony selenide (Sb2Se3) has attracted increasing attention in photovoltaic applications due to its unique quasi-one-dimensional crystal structure, suitable optical band gap with a high extinction coefficient, and excellent stability. As a promising light-harvesting material, the available synthetic methods for the fabrication of a high-quality film have been quite limited and seriously impeded both the fundamental study and the efficiency improvement. Here, we developed a facile and low-cost hydrothermal method for in situ deposition of Sb2Se3 films for solar cell applications. In this process, we apply KSbC4H4O7 and Na2SeSO3 as the antimony and selenium sources, respectively, in which thiourea (TU) serves as an additive to suppress the formation of Sb2O3 impurities. As a result, improved phase purity and enhanced crystallinity of the Sb2Se3 film are thus obtained, along with decreased trap states. Finally, the planar heterojunction Sb2Se3 solar cell delivered a power conversion efficiency of 7.9%, which is thus far the highest reported efficiency among solution-processed Sb2Se3 solar cells. This simple procedure and efficiency achievement demonstrate the great potential of the hydrothermal deposition process for the fabrication of high-efficiency Sb2Se3 solar cells.

Enhanced the photoelectrocatalytic performance of TiO2 nanotube arrays by the synergistic sensitization of Ag-AgBr nanospheres.

Ag-AgBr nanospheres were synthesized on the tubular surface of TiO2 nanotube arrays (TiO2 NTA/Ag-AgBr) by the one-pot hydrothermal deposition strategy using cetyltrimethyl ammonium bromide (CTAB) as bromine source and morphology controlling agent. The results showed that the TiO2 NTA/Ag-AgBr (0.025) prepared with 0.025 g CTAB had the uniform particle distribution, high visible light absorption, photoelectric conversion activity and photoelectrocatalytic (PEC) removal of organic dyes and heavy metal ions. The high photocatalytic decomposition of organic pollutants in waste water was attributed to the synergistic effect of Ag-AgBr nanospheres with the strong visible light response and effective separation of electron-hole pairs. The active group and photocatalytic mechanism for the rapid pollutant removal were systematically explored. This work will open the window of TiO2 NTA based photoelectrodes for the applications in solar energy conversion and dyeing waste water purification.

Polypyrrole coated ZnO nanorods on platinum wire for solid-phase microextraction of amitraz and teflubenzuron pesticides prior to quantitation by GC-MS.

The authors describe a new sorbent for amitraz and teflubenzuron pesticides. It consists of a platinum wire coated with polypyrrole-coated ZnO nanorods. The nanocomposite was prepared by a two-step process. In the first step, oriented ZnO nanorods were hydrothermally grown in situ on a platinum wire. Subsequently, oxidative vapor phase polymerization of pyrrole was performed on FeCl3-impregnated ZnO nanorods to give a porous polypyrrole film. The organic/inorganic nanocomposite synthesized through hydrothermal deposition and chemical vapor deposition polymerization yields material with attractive properties. The coated wire was applied to solid-phase microextraction of amitraz (in the form of 2,4-dimethylaniline resulting from the hydrolysis of amitraz) and teflubenzuron. The effects of extraction temperature, extraction time, sample pH value and salt concentration were optimized. The analytes 2,4-dimethylaniline and teflubenzuron were then quantified by GC-MS. Under optimum conditions, the LODs range between 0.1 and 0.15 ng.mL-1. Relative standard deviations at two concentration are <8.3% for intraday precision and <10.3% for inter-day precision. In all cases, the fiber to fiber reproducibility is <12.2%. For both analytes the linear dynamic ranges are 0.5-300 ng.mL-1. The procedure was successfully applied to the analysis of spiked agricultural water samples. Graphical abstract A novel inorganic/organic hybrid nanocomposite was synthesized through in situ hydrothermal deposition of ZnO nanorods and ten placing a thin layer of polypyrrole on them by chemical vapor deposition polymerization. This nanocomposite was applied to fabricate a solid-phase microextraction fiber for the extraction of amitraz and teflubenzuron pesticides residue from agricultural samples prior to their quantitation by GC-MS.

Effect of Ca/P ratio on the structural and corrosion properties of biomimetic CaP coatings on ZK60 magnesium alloy.

Magnesium and its alloys have attracted much attention as metallic biodegradable implants for their excellent biocompatibility and mechanical properties. However, magnesium has a poor corrosion resistance, causing its rapid degrading in vivo via an electrochemical reaction, which has become a major obstacle to their applications in implants. In this work, CaP coating was successfully coated on the ZK60 magnesium alloys by a simple hydrothermal deposition method. The mechanisms of the hydrothermal reactions of CaP coatings on Mg substrate are described in details. The effect of Ca/P ratio in the hydrothermal solution on the phase composition, microstructure and biodegradation properties of CaP coatings on ZK60 alloys was investigated by varying the Ca/P ratio from 0.83 to 4.18. The morphology of the CaP coating changed significantly with the Ca/P ratio. Biodegradation behavior of the CaP coating magnesium was characterized by anodic polarization and immersion tests in a simulated body fluid. It is revealed that the corrosion resistance of ZK60 magnesium alloy was greatly improved with the biomimetic CaP coatings, and the ZK60 alloy with CaP coating deposited at Ca/P ratio of 1.67 has the best corrosion resistance, which indicates that the CaP coatings are promising for improving the biodegradation properties of Mg-based orthopedic implants and devices.

Fabrication of novel high performance ductile poly(lactic acid) nanofiber scaffold coated with poly(vinyl alcohol) for tissue engineering applications.

Poly(lactic acid) (PLA) nanofiber scaffold has received increasing interest as a promising material for potential application in the field of regenerative medicine. However, the low hydrophilicity and poor ductility restrict its practical application. Integration of hydrophilic elastic polymer onto the surface of the nanofiber scaffold may help to overcome the drawbacks of PLA material. Herein, we successfully optimized the parameters for in situ deposition of poly(vinyl alcohol), (PVA) onto post-electrospun PLA nanofibers using a simple hydrothermal approach. Our results showed that the average fiber diameter of coated nanofiber mat is about 1265±222 nm, which is remarkably higher than its pristine counterpart (650±180 nm). The hydrophilicity of PLA nanofiber scaffold coated with a PVA thin layer improved dramatically (36.11±1.5°) compared to that of pristine PLA (119.7±1.5°) scaffold. The mechanical testing showed that the PLA nanofiber scaffold could be converted from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and in the presence of PVA. Cytocompatibility performance of the pristine and coated PLA fibers with PVA was observed through an in vitro experiment based on cell attachment and the MTT assay by EA.hy926 human endothelial cells. The cytocompatibility results showed that human cells induced more favorable attachment and proliferation behavior on hydrophilic PLA composite scaffold than that of pristine PLA. Hence, PVA coating resulted in an increase in initial human cell attachment and proliferation. We believe that the novel PVA-coated PLA nanofiber scaffold developed in this study, could be a promising high performance biomaterial in regeneration medicine.

High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded a-plane sapphire at low temperature.

Hydrothermal zinc oxide (ZnO) thick films were successfully grown on the chemical vapor deposition (CVD)-grown thick ZnO seed layers on a-plane sapphire substrates using the aqueous solution of zinc nitrate dehydrate (Zn(NO3)2). The use of the CVD ZnO seed layers with the flat surfaces seems to be a key technique for obtaining thick films instead of vertically aligned nanostructures as reported in many literatures. All the hydrothermal ZnO layers showed the large grains with hexagonal end facets and were highly oriented towards the c-axis direction. Photoluminescence (PL) spectra of the hydrothermal layers were composed of the ultraviolet (UV) emission (370 to 380 nm) and the visible emission (481 to 491 nm), and the intensity ratio of the former emission (I UV) to the latter emission (I VIS) changed, depending on both the molarity of the solution and temperature. It is surprising that all the Hall mobilities for the hydrothermal ZnO layers were significantly larger than those for their corresponding CVD seed films. It was also found that, for the hydrothermal films grown at 70°C to 90°C, the molarity dependences of I UV/I VIS resembled those of mobilities, implying that the mobility in the film is affected by the structural defects. The highest mobility of 166 cm(2)/Vs was achieved on the hydrothermal film with the carrier concentration of 1.65 × 10(17) cm(-3) grown from the aqueous solution of 40 mM at 70°C.