Unveiling Two Electron-Transport Modes in Oxygen-Deficient TiO₂ Nanowires and Their Influence on Photoelectrochemical Operation

Introducing oxygen vacancies (V_O) into TiO₂ materials is one of the most promising ways to significantly enhance light-harvesting and photocatalytic efficiencies of photoelectrochemical (PEC) cells for water splitting among others. However, the nature of electron transport in V_O-TiO₂ nanostructures is not well understood, especially in an operating device. In this work, we use the intensity-modulated photocurrent spectroscopy technique to study the electron-transport property of V_O-TiO₂ nanowires (NWs). It is found that the electron transport in pristine TiO₂ NWs displays a single trap-limited mode, whereas two electron-transport modes were detected in V_O-TiO₂ NWs, a trap-free transport mode at the core, and a trap-limited transport mode near the surface. The considerably higher diffusion coefficient (<i>D</i>_n) of the trap-free transport mode grants a more rapid electron flow in V_O-TiO₂ NWs than that in pristine TiO₂ NWs. This electron-transport feature is expected to be common in other oxygen-deficient metal oxides, lending a general strategy for promoting the PEC device performance

Constructing Fluorine-Free and Cost-Effective Superhydrophobic Surface with Normal-Alcohol-Modified Hydrophobic SiO₂ Nanoparticles

Superhydrophobic coatings have drawn much attention in recent years for their wide potential applications. However, a simple, cost-effective, and environmentally friendly approach is still lacked. Herein, a promising approach using nonhazardous chemicals was proposed, in which multiple hydrophobic functionalized silica nanoparticles (SiO₂ NPs) were first prepared as core component, through the efficient reaction between amino group containing SiO₂ NPs and the isocyanate containing hydrophobic surface modifiers synthesized by normal alcohols, followed by simply spraying onto various substrates for superhydrophobic functionalization. Furthermore, to further improve the mechanical durability, an organic–inorganic composite superhydrophobic coating was fabricated by incorporating cross-linking agent (polyisocyanate) into the mixture of hydrophobic-functionalized SiO₂ NPs and hydroxyl acrylic resin. The hybrid coating with cross-linked network structures is very stable with excellent mechanical durability, self-cleaning property and corrosion resistance

Electrodeposition of Polyporous Sn–Ni Coating in Deep Eutectic Solvents for Removing Organic Dyes

Materials with a high specific surface area including a porous structure have been widely researched due to the applicability in the adsorption of various organic dyes. However, further application of porous materials is limited by the complicated and expensive preparation process. Herein, a Sn–Ni coating with a polyporous structure is successfully prepared via a simple and high-efficiency electrodeposition approach in deep eutectic solvents (DESs). The prepared Sn–Ni coating exhibits a uniform polyporous structure with a diameter of 15 μm. Furthermore, the coating shows excellent adsorption capacity in the removal of acid grain black organic dyestuff. With the rise of preparation temperature from 85 to 105 °C, the electrochemical active surface area and the ratio of nickel increase, which further enhance dye adsorption capacity

Origin of the Different Photoelectrochemical Performance of Mesoporous BiVO₄ Photoanodes between the BiVO₄ and the FTO Side Illumination

Understanding charge separation and charge transport in mesoporous semiconductor films is crucial to designing high efficiency photoelectrochemical water splitting cells. In the present work, we systematically study the origin of the higher photoelectrochemical performance of mesoporous BiVO₄ film under FTO-side illumination (F-illumination) than that under BiVO₄-side illumination (B-illumination). Via intensity-modulated photocurrent spectroscopy in conjunction with modeling simulation of electron diffusion inside mesoporous BiVO₄ films with different thicknesses, we find that the F-illumination is more tolerant to recombination than the B-illumination, leading to a higher charge separation efficiency of the former. Specifically, we have identified a trap-free electron transport region of BiVO₄ vicinal to the FTO substrate and a trap-limited transport region farther away under F-illumination, whereas only a trap-limited transport exists under B-illumination. Simulated results accord well with the experimental data and further provide a deep insight of the detailed electron transport behavior: it is the higher electron density in the region proximal to the FTO under F-illumination that has led to the greater recombination tolerance than under B-illumination. Such a photogenerated electron transport characteristic in mesoporous films is expected to be common for other semiconductors and will inspire practicle strategies for designing high efficiency semiconductor nanostructure-based photoelectrochemical devices

Carbon-Based CsPbBr₃ Perovskite Solar Cells: All-Ambient Processes and High Thermal Stability

The device instability has been an important issue for hybrid organic–inorganic halide perovskite solar cells (PSCs). This work intends to address this issue by exploiting inorganic perovskite (CsPbBr₃) as light absorber, accompanied by replacing organic hole transport materials (HTM) and the metal electrode with a carbon electrode. All the fabrication processes (including those for CsPbBr₃ and the carbon electrode) in the PSCs are conducted in ambient atmosphere. Through a systematical optimization on the fabrication processes of CsPbBr₃ film, carbon-based PSCs (C-PSCs) obtained the highest power conversion efficiency (PCE) of about 5.0%, a relatively high value for inorganic perovskite-based PSCs. More importantly, after storage for 250 h at 80 °C, only 11.7% loss in PCE is observed for CsPbBr₃ C-PSCs, significantly lower than that for popular CH₃NH₃PbI₃ C-PSCs (59.0%) and other reported PSCs, which indicated a promising thermal stability of CsPbBr₃ C-PSCs

Highly Air-Stable Carbon-Based α‑CsPbI₃ Perovskite Solar Cells with a Broadened Optical Spectrum

Inorganic cesium lead halide perovskites with superb thermal stability show promise to fabricate long-term operational photovoltaic devices. However, the cubic phase (α) of CsPbI₃ with an appropriate band gap is unstable in air. We discover that highly stable α-CsPbI₃ can be obtained in dry air (temperature: 20–30 °C; humidity: 10–20%) by replacing PbI₂ with HPbI₃ in a one-step deposition solution. Furthermore, the band gap of HPbI₃-processed α-CsPbI₃ is advantageously reduced from 1.72 to 1.68 eV due to the existence of tensile lattice strain. By employing such an α-CsPbI₃ film in carbon-based perovskite solar cells (C-PSCs), a power conversion efficiency (PCE) of 9.5% is achieved, which is a record value for the α-CsPbI₃ PSCs without hole transport material. Most importantly, over 90% of the initial PCE is retained for nonencapsulated devices after 3000 h of storage in dry air. Therefore, HPbI₃-based one-step deposition presents a promising strategy to prepare high-performance and air-stable α-CsPbI₃ PSCs

Boron Doping of Multiwalled Carbon Nanotubes Significantly Enhances Hole Extraction in Carbon-Based Perovskite Solar Cells

Compared to the conventional perovskite solar cells (PSCs) containing hole-transport materials (HTM), carbon materials based HTM-free PSCs (C-PSCs) have often suffered from inferior power conversion efficiencies (PCEs) arising at least partially from the inefficient hole extraction at the perovskite–carbon interface. Here, we show that boron (B) doping of multiwalled carbon nanotubes (B-MWNTs) electrodes are superior in enabling enhanced hole extraction and transport by increasing work function, carrier concentration, and conductivity of MWNTs. The C-PSCs prepared using the B-MWNTs as the counter electrodes to extract and transport hole carriers have achieved remarkably higher performances than that with the undoped MWNTs, with the resulting PCE being considerably improved from 10.70% (average of 9.58%) to 14.60% (average of 13.70%). Significantly, these cells show negligible hysteretic behavior. Moreover, by coating a thin layer of insulating aluminum oxide (Al₂O₃) on the mesoporous TiO₂ film as a physical barrier to substantially reduce the charge losses, the PCE has been further pushed to 15.23% (average 14.20%). Finally, the impressive durability and stability of the prepared C-PSCs were also testified under various conditions, including long-term air exposure, heat treatment, and high humidity

Colloidal Precursor-Induced Growth of Ultra-Even CH₃NH₃PbI₃ for High-Performance Paintable Carbon-Based Perovskite Solar Cells

Carbon-based hole transport material (HTM)-free perovskite solar cells (PSCs) have attracted intense attention due to their relatively high stability. However, their power conversion efficiency (PCE) is still low, especially for the simplest paintable carbon-based PSCs (C-PSCs), whose performance is greatly limited by poor contact at the perovskite/carbon interface. To enhance interface contact, it is important to fabricate an even-surface perovskite layer in a porous scaffold, which is not usually feasible due to roughness of the crystal precursor. Herein, colloidal engineering is applied to replace the traditional crystal precursor with a colloidal precursor, in which a small amount of dimethyl sulfoxide (DMSO) is added into the conventional PbI₂ dimethylformamide (DMF) solution. After deposition, PbI₂(DMSO) adduct colloids (which are approximately tens of nanometers in size) are stabilized and dispersed in DMF to form a colloidal film. Compared with PbI₂ and PbI₂(DMSO) adduct crystal precursors deposited from pure DMF and DMSO solvents, respectively, the PbI₂(DMSO) adduct colloidal precursor is highly mobile and flexible, allowing an ultra-even surface to be obtained in a TiO₂ porous scaffold. Furthermore, this ultra-even surface is well-maintained after chemical conversion to CH₃NH₃PbI₃ in a CH₃NH₃I solution. As a result, the contact at the CH₃NH₃PbI₃/carbon interface is significantly enhanced, which largely boosts the fill factor and PCE of C-PSCs. Impressively, the achieved champion PCE of 14.58% is among the highest reported for C-PSCs

Identification of ANXA2 (annexin A2) as a specific bleomycin target to induce pulmonary fibrosis by impeding TFEB-mediated autophagic flux

<p>Bleomycin is a clinically potent anticancer drug used for the treatment of germ-cell tumors, lymphomas and squamous-cell carcinomas. Unfortunately, the therapeutic efficacy of bleomycin is severely hampered by the development of pulmonary fibrosis. However, the mechanisms underlying bleomycin-induced pulmonary fibrosis, particularly the molecular target of bleomycin, remains unknown. Here, using a chemical proteomics approach, we identify ANXA2 (annexin A2) as a direct binding target of bleomycin. The interaction of bleomycin with ANXA2 was corroborated both in vitro and in vivo. Genetic depletion of <i>anxa2</i> in mice mitigates bleomycin-induced pulmonary fibrosis. We further demonstrate that Glu139 (E139) of ANXA2 is required for bleomycin binding in lung epithelial cells. A CRISPR-Cas9-engineered ANXA2^E139A mutation in lung epithelial cells ablates bleomycin binding and activates TFEB (transcription factor EB), a master regulator of macroautophagy/autophagy, resulting in substantial acceleration of autophagic flux. Pharmacological activation of TFEB elevates bleomycin-initiated autophagic flux, inhibits apoptosis and proliferation of epithelial cells, and ameliorates pulmonary fibrosis in bleomycin-treated mice. Notably, we observe lowered TFEB and LC3B levels in human pulmonary fibrosis tissues compared to normal controls, suggesting a critical role of TFEB-mediated autophagy in pulmonary fibrosis. Collectively, our data demonstrate that ANXA2 is a specific bleomycin target, and bleomycin binding with ANXA2 impedes TFEB-induced autophagic flux, leading to induction of pulmonary fibrosis. Our findings provide insight into the mechanisms of bleomycin-induced fibrosis and may facilitate development of optimized bleomycin therapeutics devoid of lung toxicity.</p