Experimental and characterization data supporting the study from Inkjet-printed SnO_x as an effective electron transport layer for planar perovskite solar cells and the effect of Cu doping

Inkjet printing is a more sustainable and scalable fabrication method than spin coating for producing perovskite solar cells (PSCs). Although spin-coated SnO2 has been intensively studied as an effective electron transport layer (ETL) for PSCs, inkjet-printed SnO2 ETLs have not been widely reported. Here, we fabricated inkjet-printed, solution-processed SnOx ETLs for planar PSCs. A champion efficiency of 17.55% was achieved for the cell using a low-temperature processed SnOx ETL. The low-temperature SnOx exhibited an amorphous structure and outperformed the high-temperature crystalline SnO2. The improved performance was attributed to enhanced charge extraction and transport and suppressed charge recombination at ETL/perovskite interfaces, which originated from enhanced electrical and optical properties of SnOx, improved perovskite film quality, and well-matched energy level alignment between the SnOx ETL and the perovskite layer. Furthermore, SnOx was doped with Cu. Cu doping increased surface oxygen defects and upshifted energy levels of SnOx, leading to reduced device performance. A tunable hysteresis was observed for PSCs with Cu-doped SnOx ETLs, decreasing at first and turning into inverted hysteresis afterwards with increasing Cu doping level. This tunable hysteresis was related to the interplay between charge/ion accumulation and recombination at ETL/perovskite interfaces in the case of electron extraction barriers

Mechanism and Kinetics of Propane and <i>n</i>‑Butane Dehydrogenation over Isolated and Nested SiOZn–OH Sites Grafted onto Silanol Nests of Dealuminated Beta Zeolite

Zn Lewis acid centers were grafted onto the silanol nest created by dealumination of H-BEA zeolite (DeAlBEA). The resulting material was characterized and investigated for propane dehydrogenation to propene and n-butane dehydrogenation to 1,3-butadiene (1,3-BD). For Zn/Al molar ratios (Al is the molar amount in H-BEA) below 0.12, Zn sites are present as isolated (SiOZn–OH) species, but for Zn/Al ratios between 0.12 and 0.60, the SiOZn–OH species form nests in which enhanced electron transfer between Zn and O atoms of the neighboring SiOZn–OH group and H-bonding interaction between adjacent Zn–OH groups occur. The turnover frequency (TOF) for both propane and n-butane dehydrogenation is virtually identical for Zn-DeAlBEA for Zn/Al < 0.12 and then increases almost linearly with increasing Zn/Al ratio from 0.12 to 0.36, indicating the superior activity of Zn atoms in SiOZn–OH nests. In the case of 1-butene dehydrogenation, identical activity is observed for both isolated and nested SiOZn–OH sites. The kinetics of these three reactions was investigated to clarify the difference in activity. The rate coefficient for the forward reaction (dehydrogenation) was found to be 173 mol propene/(mol Zn sites·bar·h) at 773 K over SiOZn–OH nests, and that for the forward n-butane dehydrogenation was found to be 1193 mol butene/(mol Zn sites·bar·h) at 823 K, a value that is significantly higher than those for most other supported non-noble metal catalysts. Regeneration experiments for propane and n-butane dehydrogenation over 0.60Zn-DeAlBEA suggest a good stability of Zn atom in SiOZn–OH nests

Robust Interfacial Effect in Multi-interface Environment through Hybrid Reconstruction Chemistry for Enhanced Energy Storage

Electrochemical-oxidation-driven reconstruction has emerged as an efficient approach for developing advanced materials, but the reconstructed microstructure still faces challenges including inferior conductivity, unsatisfying intrinsic activity, and active-species dissolution. Herein, we present hybrid reconstruction chemistry that synergistically couples electrochemical oxidation with electrochemical polymerization (EOEP) to overcome these constraints. During the EOEP process, the metal hydroxides undergo rapid reconstruction and dynamically couple with polypyrrole (PPy), resulting in an interface-enriched microenvironment. We observe that the interaction between PPy and the reconstructed metal center (i.e., Mn > Ni, Co) is strongly correlated. Theoretical calculation results demonstrate that the strong interaction between Mn sites and PPy breaks the intrinsic limitation of MnO2, rendering MnO2 with a metallic property for fast charge transfer and enhancing the ion-adsorption dynamics. Operando Raman measurement confirms the promise of EOEP-treated Mn(OH)2 (E-MO/PPy) to stably work under a 1.2 V potential window. The tailored E-MO/PPy exhibits a high capacitance of 296 F g–1 at a large current density of 100 A g–1. Our strategy presents breakthroughs in upgrading the electrochemical reconstruction technique, which enables both activity and kinetics engineering of electrode materials for better performance in energy-related fields

High-Performance Lithium-Ion Batteries with High Stability Derived from Titanium-Oxide- and Sulfur-Loaded Carbon Spherogels

This study presents a novel approach to developing high-performance lithium-ion battery electrodes by loading titania-carbon hybrid spherogels with sulfur. The resulting hybrid materials combine high charge storage capacity, electrical conductivity, and core-shell morphology, enabling the development of next-generation battery electrodes. We obtained homogeneous carbon spheres caging crystalline titania particles and sulfur using a template-assisted sol-gel route and carefully treated the titania-loaded carbon spherogels with hydrogen sulfide. The carbon shells maintain their microporous hollow sphere morphology, allowing for efficient sulfur deposition while protecting the titania crystals. By adjusting the sulfur impregnation of the carbon sphere and varying the titania loading, we achieved excellent lithium storage properties by successfully cycling encapsulated sulfur in the sphere while benefiting from the lithiation of titania particles. Without adding a conductive component, the optimized material provided after 150 cycles at a specific current of 250 mA g–1 a specific capacity of 825 mAh g–1 with a Coulombic efficiency of 98%

Layered Bi₂Se₃ Nanoplate/Polyvinylidene Fluoride Composite Based n‑type Thermoelectric Fabrics

In this study, we report the fabrication of n-type flexible thermoelectric fabrics using layered Bi₂Se₃ nanoplate/polyvinylidene fluoride (PVDF) composites as the thermoelectric material. These composites exhibit room temperature Seebeck coefficient and electrical conductivity values of −80 μV K^–1 and 5100 S m^–1, respectively, resulting in a power factor approaching 30 μW m^–1K^–2. The temperature-dependent thermoelectric properties reveal that the composites exhibit metallic-like electrical conductivity, whereas the thermoelectric power is characterized by a heterogeneous model. These composites have the potential to be used in atypical applications for thermoelectrics, where lightweight and flexible materials would be beneficial. Indeed, bending tests revealed excellent durability of the thermoelectric fabrics. We anticipate that this work may guide the way for fabricating high performance thermoelectric fabrics based on layered V–VI nanoplates

Bi₂Te₃ Plates with Single Nanopore: The Formation of Surface Defects and Self-Repair Growth

Self-assembly has proven to be a powerful method of preparing structurally intricate nanostructures. In this work, we design a nanoscale “Chinese Coin” based on Bi₂Te₃ nanoplates (NPs) by using a simple and scalable solution process; i.e., a single pore is introduced on a hexagonal/round plate similar to a fender washer. The diameter of the nanopores is well controlled within the range of 5–100 nm and depends strongly on the reaction time and heating temperatures, suggesting a kinetics related mechanism. Moreover, the thermal evolution of stable Bi₂Te₃ plate-pore structures was systematically explored to elucidate the underlying energetics of the V₂-VI₃ chalcogenides. We found that the nanopore is initiated near the middle of the plate, followed by the successive removal of Bi₂Te₃ slices from the high edge-energy pore with increased temperatures (70–150 °C), leading finally to the formation of a stable nanopore. The morphology of the pore as well as the local lattice crystallinity was studied using high-resolution transmission electron microscopy and first-principles calculations. On the basis of these observations, a self-repair mechanism for pores under the stability diameter is proposed from the viewpoint of reaction kinetics

Hydrazine-Free Surface Modification of CZTSe Nanocrystals with All-Inorganic Ligand

The optoelectronic properties of semiconductor nanoparticles (NPs) depend sensitively on their surface ligands. However, introducing certain organic ligands to the solution-synthesized CZTSe NPs unfavorably suppresses the interaction among those NPs. These organic ligands prevent the NPs from dissolving in water and create an insulating barrier for charge transportation, which is the key property for semiconductor devices. In our study, by adopting Na₂S to displace the associated organic ligands on Cu₂ZnSnSe₄ (CZTSe), we obtained high solubility NPs in an environmentally friendly polar solvent as well as excellent charge transport properties. Toxicity of CZTSe: Na₂S NPs was determined to be around 10 mg/L. Because of the inorganic ligand S^2– around CZTSe NPs, thin films can be easily fabricated by solution processing out of benign solvents like water and ethanol. After annealing, a homogeneous CZTSSe absorbing layer without carbon point defects was obtained. As the S^2– effectively facilitates the electronic coupling in nanocrystal thin films, carrier mobility of the surface-engineered CZTSe enhances from 4.8 to 8.9 cm²/(Vs). This raises the possibility for engineering chalcogenide materials by controlling the surface properties during the fabrication process

Interface Engineering of Colloidal CdSe Quantum Dot Thin Films as Acid-Stable Photocathodes for Solar-Driven Hydrogen Evolution

Colloidal semiconductor quantum dot (CQD)-based photocathodes for solar-driven hydrogen evolution have attracted significant attention because of their tunable size, nanostructured morphology, crystalline orientation, and band gap. Here, we report a thin film heterojunction photocathode composed of organic PEDOT:PSS as a hole transport layer, CdSe CQDs as a semiconductor light absorber, and conformal Pt layer deposited by atomic layer deposition (ALD) serving as both a passivation layer and cocatalyst for hydrogen evolution. In neutral aqueous solution, a PEDOT:PSS/CdSe/Pt heterogeneous photocathode with 200 cycles of ALD Pt produces a photocurrent density of −1.08 mA/cm² (AM-1.5G, 100 mW/cm²) at a potential of 0 V versus reversible hydrogen electrode (RHE) (<i>j</i>₀) in neutral aqueous solution, which is nearly 12 times that of the pristine CdSe photocathode. This composite photocathode shows an onset potential for water reduction at +0.46 V versus RHE and long-term stability with negligible degradation. In the acidic electrolyte (pH = 1), where the hydrogen evolution reaction is more favorable but stability is limited because of photocorrosion, a thicker Pt film (300 cycles) is shown to greatly improve the device stability and a <i>j</i>₀ of −2.14 mA/cm² is obtained with only 8.3% activity degradation after 6 h, compared with 80% degradation under the same conditions when the less conformal electrodeposition method is used to deposit the Pt layer. Electrochemical impedance spectroscopy and time-resolved photoluminescence results indicate that these enhancements stem from a lower bulk charge recombination rate, higher interfacial charge-transfer rate, and faster reaction kinetics. We believe that these interface engineering strategies can be extended to other colloidal semiconductors to construct more efficient and stable heterogeneous photoelectrodes for solar fuel production

Dehydrogenation of Propane and <i>n</i>‑Butane Catalyzed by Isolated PtZn₄ Sites Supported on Self-Pillared Zeolite Pentasil Nanosheets

Propene and 1,3-butadiene are important building-block chemicals that can be produced by dehydrogenation of propane and butane on Pt catalysts. A challenge is to develop highly active and selective catalysts that are resistant to deactivation by Pt sintering and coke formation. We have recently shown (Qi, J. Am. Chem. Soc.2021, 143, 21364−21378) that these objectives can be met for propane dehydrogenation (PDH) using atomically dispersed Pt anchored to neighboring SiOZn-OH groups bonded to the framework of dealuminated zeolite BEA. In the present study, we demonstrate that significantly superior performance can be achieved using self-pillared pentasil (SPP) zeolite nanosheets as supports. Following catalyst reduction in H2, atomic resolution, scanning transmission electron microscopy (STEM), and X-ray absorption spectroscopy (XAS) indicate that Pt is stabilized in structures well approximated as (Si-O-Zn)4‑5Pt. These species are highly active, selective, and stable for PDH to give propene and for n-butane dehydrogenation (BDH) to give 1,3-butadiene. No catalyst deactivation was observed after 12 days of time on stream, and the selectivity remained at nearly 100% for PDH conducted at 823 K and a weight hourly space velocity (WHSV) of 1350 h–1. The apparent rate coefficient for PDH on this catalyst is significantly higher than that reported previously for Pt-containing catalysts. For BDH at 823 K and a WHSV of 3560 h–1, the selectivity to butene isomers and 1,3-butadiene is 98.9%, and the selectivity to 1,3-butadiene is 45%. We propose that the high catalyst stability observed during PDH and BDH is a consequence of a large fraction of the Pt-containing centers being located on the external surface of the zeolite nanosheets, where nascent coke precursors can desorb before condensing to form coke

High-Capacity, Cooperative CO₂ Capture in a Diamine-Appended Metal–Organic Framework through a Combined Chemisorptive and Physisorptive Mechanism

Diamine-appended Mg2(dobpdc) (dobpdc4– = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate) metal–organic frameworks are promising candidates for carbon capture that exhibit exceptional selectivities and high capacities for CO2. To date, CO2 uptake in these materials has been shown to occur predominantly via a chemisorption mechanism involving CO2 insertion at the amine-appended metal sites, a mechanism that limits the capacity of the material to ∼1 equiv of CO2 per diamine. Herein, we report a new framework, pip2–Mg2(dobpdc) (pip2 = 1-(2-aminoethyl)piperidine), that exhibits two-step CO2 uptake and achieves an unusually high CO2 capacity approaching 1.5 CO2 per diamine at saturation. Analysis of variable-pressure CO2 uptake in the material using solid-state nuclear magnetic resonance (NMR) spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveals that pip2–Mg2(dobpdc) captures CO2 via an unprecedented mechanism involving the initial insertion of CO2 to form ammonium carbamate chains at half of the sites in the material, followed by tandem cooperative chemisorption and physisorption. Powder X-ray diffraction analysis, supported by van der Waals-corrected density functional theory, reveals that physisorbed CO2 occupies a pocket formed by adjacent ammonium carbamate chains and the linker. Based on breakthrough and extended cycling experiments, pip2–Mg2(dobpdc) exhibits exceptional performance for CO2 capture under conditions relevant to the separation of CO2 from landfill gas. More broadly, these results highlight new opportunities for the fundamental design of diamine–Mg2(dobpdc) materials with even higher capacities than those predicted based on CO2 chemisorption alone