In this paper, ZnS/SnO2 composite photocatalysts with different molar ratios were prepared by a two-step hydrothermal method. The influence of ZnS composite ratio on the material structure, morphology, optical properties and photocatalytic performance was systematically investigated. XRD and XPS results indicate that the SnO precursor is completely transformed into rutile SnO2 during the hydrothermal process, and ZnS is composited on the SnO2 surface in the form of cubic sphalerite, forming a heterostructure rather than a solid solution. SEM, TEM and EDS show that the composite exhibits a porous nano-aggregate morphology with a close heterojunction interface formed between ZnS and SnO2. BET analysis reveals that the material possesses a mesoporous structure with a specific surface area of 14.36 m2/g. UV-vis absorption spectra show that the absorption edge of the composite is red-shifted, extending the photoresponse range to the visible region. The photocatalytic degradation experiments of rhodamine B (RhB) demonstrate that the composite with a ZnS ratio of 80% (0.8-ZnS/SnO2) exhibits the best performance, achieving a degradation rate of 93.52% within 70 min and a reaction rate constant of 3.74×10-2 min-1, which is about 5 times that of commercial P25. Cyclic catalytic tests prove that the composite has good reusability and photostability. This study provides a feasible synthesis strategy and structural optimization basis for constructing efficient type II heterojunction photocatalysts.

In this study, three-dimensional hierarchical SnS2 nanoflowers assembled from nanosheets with an average thickness of 13 nm were synthesized via a facile hydrothermal method. Ag nanoparticles were then modified on the surface of SnS2 by an in-situ chemical reduction method to form Ag/SnS2 nanocomposites. The introduction of Ag nanocrystals could enhance the response and stability toward NO2 gas and decrease the optimal operating temperature from 100 degrees C to 80 degrees C. And the Ag/SnS2-based sensor with an Ag content of 1.0 at% (1.0-Ag/SnS2) exhibited the maximum sensitivity and excellent selectively. The response value (60) of the 1.0-Ag/SnS2 sensor to 8 ppm NO2 at 80 degrees C was 3.75 times higher than that (16) of the pristine SnS2 sensor at 100 degrees C. The improved sensing properties could be attributed to the spillover effect of Ag nanocrystals and the formation of Schottky junction between Ag and SnS2. Furthermore, the adsorption energies of Ag-modified SnS2 for NO2 molecules were calculated using first-principles calculations. The results suggested a strong adsorption capacity and interaction between NO2 and Ag/SnS2, which was beneficial for enhancing the gas-sensing performances.

The electron transport layer (ETL) is critical in hole-transport-layer-free all-inorganic perovskite solar cells (PSCs). Although ZnO as an ETL exhibits high electron mobility and suitable energy levels, its high surface defect density often leads to interfacial recombination losses. In this study, PbCl2 was incorporated into the ZnO ETL to passivate interfacial defects and optimize the energy level alignment. PSCs with a structure of FTO/PbCl2–ZnO/CsPbBr3/Carbon were fabricated. The resulting carbon-based CsPbBr3 solar cells achieved a power conversion efficiency (PCE) of 7.0

To address the issues of narrow photoresponse range, rapid carrier recombination, and difficulty in recovery associated with TiO2 photocatalytic materials, this study employed a morphology control strategy to fabricate hollow spherical TiO2 structures. By optimizing the microstructure of the hollow spheres, the aim was to broaden the light absorption range, increase the specific surface area, and enhance carrier separation. The photocatalytic degradation performance of the prepared material toward Rhodamine B aqueous solution-a typical organic pollutant-was experimentally evaluated, and its enhancement mechanism was explored. This work provides a feasible approach for designing efficient and easily recoverable TiO2 photocatalysts.

In this paper, CdS/SnO2 heterojunction photocatalysts with different CdS composite ratios were prepared via a hydrothermal method. Their phase structure, microstructure, specific surface area, surface chemical state, optical properties, and photocatalytic performance were systematically investigated. XRD results indicate that CdS and SnO2 coexist in the form of a physical heterointerface without lattice doping or distortion. TEM/HRTEM and EDS analyses show that SnO2 nanoparticles are uniformly dispersed on the surface of the CdS plate-like structure, forming a closely contacted heterointerface that facilitates efficient separation of photogenerated charge carriers. BET tests reveal that the composite possesses a mesoporous structure with a specific surface area of 23.82 m2/g. XPS analysis confirms the existence of a built-in electric field at the heterojunction interface, consistent with type II band alignment characteristics. UV-Vis absorption spectra demonstrate that the introduction of CdS extends the photoresponse range into the visible light region, with the 0.6-CdS/SnO2 (Cd:Sn = 3:5) sample exhibiting the strongest light absorption capability. PL and TRPL further demonstrate that this sample has the highest photogenerated carrier separation efficiency. Photocatalytic degradation experiments of Rhodamine B (RhB) show that 0.6-CdS/SnO2 achieves a degradation rate of 93.43% within 70 min, with a reaction rate constant of 3.75×10-2 min-1, approximately 4.88 times that of commercial P25 catalyst. Cyclic test results indicate that the composite material possesses good photocatalytic stability and reusability.

This work reports greatly boosted H2S sensing performances of nanoflower-structured Pt/SnO2/CuO heterostructures via a facile controlled acid etching strategy. The hierarchical nanoflowers were synthesized by hydrothermal synthesis followed by in-situ chemical reduction, and precise HCl etching (5-15 min) rationally modulates the SnO2/CuO heterointerface and tunes the built-in p-n heterojunction. Ex-situ XPS characterizations directly confirm partial sulfidation from surface CuO to CuS upon H2S exposure, unambiguously uncovering the interfacial chemical evolution during gas-sensing reactions. Benefiting from interface optimization, the etched sensor reduces its optimal working temperature from 200 degrees C (pristine sample) to 160 degrees C and delivers an ultrahigh response of 812 toward 7 ppm H2S, similar to 22.4-fold enhancement relative to the unetched counterpart, alongside improved sensing stability. DFT calculations further verify that the engineered etched heterointerface facilitates charge redistribution and target gas adsorption. This work highlights the crucial role of interface engineering in heterostructured metal oxides for developing highly sensitive gas sensors.

A novel gas sensor based on CH3NH3Pb(I1 − xBrx)3 (MAPb(I1 − xBrx)3) perovskite materials was prepared to achieve the detection of NH3 gas at room temperature of 25℃. The TiO2 nanorod arrays were first synthesized on FTO glass through the hydrothermal method, and then MAPb(I1 − xBrx)3 perovskite films were fabricated using a one-step spin-coating technique. Following Br doping, the morphology of the MAPb(I1 − xBrx)3 perovskite film transitions from a dendritic to a tubular structure, leading to enhanced film quality and crystallinity. The gas-sensing test results demonstrate that the response of the MAPb(I0.85Br0.15)3 sensor to 100 ppm ammonia is 36.8

Accurate monitoring of nitrogen dioxide (NO2) is critical for environmental protection and human health. In this study, hierarchical SnS2 hollow microspheres assembled from nanosheets were synthesized via a hydrothermal method, followed by the in-situ oxidation of SnS2 to form SnO2/SnS2 nanocomposites at calcination temperatures ranging from 300 to 400 degrees C. The synergistic effect of the unique hollow morphology and the SnO2-SnS2 heterojunction significantly enhanced the NO2 sensing performance. Gas-sensing tests revealed that the SnO2/SnS2-320 sensor (calcined at 320 degrees C) exhibited a better response value of 50 toward 5 ppm NO2 at an optimal operating temperature of 100 degrees C, which is approximately 5 times higher than that of pristine SnS2. Additionally, the SnO2/SnS2-320 sensor demonstrated excellent repeatability, long-term stability, and selectivity toward NO2. Density functional theory (DFT) calculations further confirmed that the SnO2/SnS2 heterostructure exhibited a higher NO2 adsorption energy (-0.040 eV) compared to pure SnS2 (-0.001 eV), indicating stronger chemisorption, which is consistent with the experimental results. This work provides a novel structural design strategy for developing high-performance NO2 sensors.

In this study, a higher quality MA0.9FA0.1PbI2.85Br0.15 film was surface treated with phenylethylamine iodide (PEAI), and a perovskite solar cell (PSC) with high stability and high efficiency carbon pair electrode was prepared. The I- and PEA+ ions in PEAI fill the defects between the perovskite crystals, passivate the surface, improve the quality of the film, increase the size of the perovskite grains, reduce the carrier recombination, and enhance the optical properties. By comparing and testing the effect of a series of different PEAI solution concentrations on the quality of MA0.9FA0.1PbI2.85Br0.15 film, the optimal concentration of PEAI solution is 1.5mg /mL, and the optimal PCE of the device is 11.25%. PSCs were higher than those of untreated MA0.9FA0.1PbI2.85Br0.15 films. The unpackaged and PEAI solution surface treated battery devices are more stable in an air atmosphere, and the PCE of the device after 60 days remains at 96% of the initial PCE.

Heterojunction composite structures engineered with homo-metallic elements are an effective strategy for boosting gas sensing capabilities due to their ability to effectively reduce the contact barrier for charge transfer. In this study, iso-elemental SnO/SnO2 micro-rod composites were fabricated through hydrothermal synthesis followed by calcination. The gas sensing performance revealed that SnO/SnO2 microstructure when calcined at 400 degrees C (referred to as M1-400), displays remarkable long-term stability, with a response value of 21.05 and the quickest recovery time of 38 s-100 ppm of formaldehyde (HCHO) at 320 degrees C, outperforming other sensors. Further investigation indicates that the enhanced sensitivity of M1-400 can be attributed to the p-n heterojunction of SnO-SnO2 facilitating electron transport, and its increased adsorption affinity for HCHO due to higher vacuum and oxygen content. This synthesis strategy for SnO/SnO2 suggests that this material is promising for HCHO gas sensing applications and could offer a potentially straightforward method for preparing onedimensional metal oxides.

Recently, the detection of acetone by using a gas sensor fabricated with metal oxide semiconductors has stimulated intense research enthusiasm, owing to its promising application in the noninvasive diagnosis of diabetes by monitoring human exhaled breath. In this work, a potential acetone sensor was fabricated by comodification of the nanosheets-assembled ZnCo2O4 hierarchical microspheres (HMSs) with MoO3 and Ag nanoparticles (NPs). The ZnCo2O4 HMSs were synthesized via a solvothermal route and then sequentially modified with MoO3 and Ag NPs via immersion, calcination, and photoreduction routes. The results of gas sensing measurement indicated that after modification with MoO3 and Ag, a continuous improvement of acetone sensitivity was realized on the ZnCo2O4 sensor. At the optimal working temperature of 260 °C, the response of the best Ag/MoO3/ZnCo2O4 sensor to 50 ppm of acetone was 7.23, which was about 3.3 and 1.4 times higher than that of ZnCo2O4 and MoO3/ZnCo2O4, respectively. Apart from the higher response, the selectivity and response speed of the Ag/MoO3/ZnCo2O4 sensor were also improved. The results of density functional theory calculations showed that the enhanced absorbability of ZnCo2O4 for acetone after modification with MoO3 and Ag should be responsible for the improved acetone sensitivity and selectivity of the Ag/MoO3/ZnCo2O4 sensor.

The all-inorganic perovskite quantum dot CsPbX3 (X = Cl, Br, I) exhibits unique optical properties enabled by its bandgap tunability. CsPbX3 quantum dots with varying I⁻ doping ratios were synthesized via ligand-assisted reprecipitation (LARP). Appropriate I⁻ doping can effectively modulate the lattice parameters of the quantum dots, resulting in a redshift of the absorption band edge and a narrowing of the optical band gap in the ultraviolet-visible absorption spectrum. Excessive I⁻ doping induces a 91% reduction in fluorescence quantum yield due to lattice distortion. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses confirmed that the quantum dot size was highly uniform and the monoclinic crystal phase remained stable. Ultraviolet-visible diffuse reflection spectroscopy and fluorescence spectroscopy elucidated the synergistic effects of quantum confinement and exciton recombination dynamics. This study underscores the significant impact of I⁻ doping on Br-based perovskites, providing a foundation for the rational design of heterojunctions in perovskite systems.

Organic-inorganic hybrid perovskite materials have garnered significant research interest owing to their exceptional crystallographic characteristics and remarkable optoelectronic properties. This study presents a breakthrough in room-temperature ammonia sensing through the rational design of CH3NH3PbI3 (MAPbI(3))-based chemiresistive sensors modified with monoethanolamine (MEA) ligands. By integrating MEA as a coordination agent into the perovskite precursor solution, we achieved controlled crystallization dynamics, yielding compact MAPbI(3) films with unique maple-leaf grain morphology and enhanced humidity resistance. The optimized TiO2/MEA-MAPbI(3) sensor exhibited a nearly 2.1-fold improvement in response amplitude toward 100 ppm NH3 compared to unmodified counterparts, alongside exceptional selectivity to NH3 against interfering gases. Crucially, MEA-derived (PbI2)-MEA-(MAI) molecular shielding layers at grain boundaries suppressed moisture-induced degradation, enabling stable operation in air environment (similar to 30 %RH) with less than 22 % response degradation over 29 days. Mechanistic analyses revealed that the sensing behavior originates from reversible cation exchange between methylammonium (MA(+)) and ammonium (NH4+) species at the perovskite surface, corroborated by density functional theory (DFT) calculations showing preferential NH3 adsorption over other analyte gases.

Tin oxide (SnO2) has been widely investigated as a sensing material for formaldehyde due to its high electron mobility. However, there are relatively reports about SnO2 iso-element heterojunctions and using rare earthdoping for selective detection of formaldehyde sensors, along these lines. In this study, SnO-SnO2 micro-rods with varying La3+ ion concentrations were synthesized by simple hydrothermal reaction and sintered process. The sensor doped with 3 % mol La exhibited outstanding sensing capabilities, demonstrating a high response of 51.97 and a response time quickly within 20 s when detecting 100 ppm HCHO at 280 degrees C. The sensing mechanism indicates that the enhanced formaldehyde detection performance is attributed to the increase of specific surface area and the elevated concentrations of vacancy and adsorbed oxygen, this investigation introduces a novel approach to fabricating a La-functionalized SnO-SnO2 micro-rods structure, positioning it as a promising contender for formaldehyde detection applications.

In this study, under fixed cation stoichiometry, the effects of Br⁻ doping with varying ratios on the structural and optoelectronic properties of perovskite films and corresponding device performance were systematically investigated. The substitution of Br⁻ for partial I⁻ in the perovskite lattice demonstrated significant morphological refinement and enhanced crystallographic quality, as evidenced by reduced defect density and grain boundary formation. The optimized composition, MA₀.₉FA₀.₁PbI₂.₈₅Br₀.₁₅, exhibited superior film uniformity and crystallinity, which translated into improved photovoltaic parameters in carbon-electrode-based perovskite solar cells (PSCs). The champion device achieved a power conversion efficiency (PCE) of 9.33%, outperforming the undoped MA₀.₉FA₀.₁PbI₃ counterpart. Environmental stability assessments revealed that unencapsulated Br⁻-doped devices maintained 92% of their initial PCE after 60 days in ambient atmosphere (25°C, 40–60% RH), demonstrating markedly enhanced operational durability compared to the undoped control group. This work highlights halogen engineering as an effective strategy for simultaneously optimizing phase stability and defect passivation in mixed-halide perovskite systems.

MXene-based absorbers have shown promising application prospects because of their sophisticated structural design and clever material composites. However, the intrinsic MXene materials themselves have not achieved significant breakthroughs in microwave absorption (MA) performance. Therefore, the development of novel and efficient pure MXene absorbing materials is imperative to address inherent mismatches in electromagnetic parameters, highlighting the urgent need in this area. Here, a straightforward strategy involving etching time modulation is proposed to customize the electromagnetic wave (EMW) absorption properties of delaminated Mo2CTx MXene. The impact of varying etching degrees on the EMW absorption capabilities of Mo2CTx MXenes was systematically investigated through controlled etching durations of Mo2Ga2C MAX phase. Among them, the sample etched for 12 h achieved an effective absorption bandwidth (EAB) of 4.4 GHz at an ultrathin thickness of 1.3 mm, and the strongest reflection loss (RL) value was as high as −60.7 dB when the sample etching time was increased to 24 h. The improvement in absorbing performance was attributed to the dielectric loss and polarization process induced by terminal functional groups and surface-rich defects, which optimized impedance matching. This work establishes that intrinsic Mo2CTx MXene materials with superior absorbing properties outperform traditional pure MXenes, providing a strong basis for advancing Mo-based MXene absorptive materials.

Morphology regulation is an effective strategy for improving the sensor sensitivity of transition metal oxide nanostructures. In this work, SnO2 with three different morphologies (nanorods, nanoparticles, and nanopillars) has been synthesized by a simple one-step solvothermal process with the addition of various solute ratios at 180 degrees C for 6 h for detecting formaldehyde (HCHO) at the optimum working temperature of 320 degrees C. Compared to nanorods and nanopillars, the created SnO2 nanoparticles exhibit a much faster response time and sensitivity than other samples, showing the fastest recovery time (18 s) with the highest sensitivity of 6-100 ppm of the HCHO gas. The sensing mechanism of the sensors is investigated by Brunauer-Emmett-Teller (BET) methods and X-ray photoelectron spectroscopy (XPS) analysis, revealing that the pore size distribution and amount of O-V and O-C improve the charge transfer and HCHO adsorption of nanoparticle sensors. Such an effect of morphology control on sensing performance paves an idea for the development of different structure-based HCHO sensors.

In this study, a hybrid anti-solvent treatment was used to prepare high-quality MA(0.9)FA(0.1)PbI(3) perovskite film, and perovskite solar cells (PSCs) with carbon counter electrodes of high stability and high efficiency were fabricated. Different ratios of chlorobenzene (CB) and toluene (TL) were utilized as binary anti-solvent, and dropwise addition was initiated within spin-coating perovskite film. By optimizing the ratio of CB and TL, the formation process of perovskite film was effectively controlled and the crystallinity and coverage of the perovskite film were improved. The carbon electrode PSCs composed of MA(0.9)FA(0.1)PbI(3) film treated with anti-solvent exhibited a maximum power conversion efficiency (PCE) of 12.21% under air atmosphere conditions, which was higher than that of the PSCs of MA(0.9)FA(0.1)PbI(3) film without anti-solvent treatment. Finally, PSCs showed that the device still exhibits 90% of the initial efficiency after being stored in the air for 100 d, which shows excellent stability.

The CsPbBr3 perovskite solar cells (PSCs) based on carbon counter electrode (CCE) are promising because of the advantages including fabrication simplicity and excellent stability, but their power conversion efficiencies (PCE) are low due to interfacial carrier recombination as the direct contact of the CsPbBr3 with electron transport materials (ETM). In this paper, PbTiO3 shells were grown onto TiO2 nanorods to form PbTiO3-coated TiO2 scaffold layer via a two-step method. The presence of PbTiO3 could promote crystallinity of the CsPbBr3 perovskite film and inhibits interface recombination at the CsPbBr3/TiO2 interface. Consequently, the carbon-based CsPbBr3 solar cells with PbTiO3/TiO2 scaffold layer achieves a high PCE of 7.28%, demonstrating an increase by 19.9% compared with the devices based on TiO2 NRs. Moreover, the champion devices exhibited excellent stability in ambient air, with the PCE value remaining at 93% over 28 days.

The three-dimensional (3D) microstructures assembled by nanomaterials have attracted great attention due to their unique hierarchical structure and large surface area. In this study, the hierarchical nanosheets-assembled SnS2 hollow microspheres with an average diameter of 6.1 μm were synthesized via a facile hydrothermal method. Then Pt nanoparticles were deposited on the surface of SnS2 to form Pt/SnS2 nanocomposites using the in-situ reduction method. Compared with pristine SnS2-based sensors, the Pt/SnS2 sensors exhibited improved gas-sensing performances to NO2 gas, including higher sensitivity, shorter response time, and better selectivity. The superior sensing performance can be ascribed to the Schottky junction created between Pt and SnS2, along with the catalytic effect of Pt. Moreover, the adsorption energy of SnS2 and Pt-modified SnS2 for NO2 molecules was calculated using first principles based on density functional theory (DFT). The Pt modification can enhance the interaction of NO2 with the SnS2 surface, which is favorable for improving the gas-sensing properties. This work provides novel hierarchical SnS2 microspheres based gas sensors for NO2 detection.