Solvothermal-Etching Process Induced Ti-Doped Fe₂O₃ Thin Film with Low Turn-On Voltage for Water Splitting

In this work, a thinning process of hematite film accompanied by simultaneous titanium (Ti) doping has been demonstrated. Ti⁴⁺ ion was incorporated into ultrathin Fe₂O₃ film by solvothermally etching a hematite film fabricated on titanium nanorod array substrate. As a consequence, the onset potential (<i>V</i>_on) of oxygen evolution reaction for final ultrathin Ti-doped Fe₂O₃ film shifted toward cathodic substantially, a very low <i>V</i>_on of 0.48 V_RHE was realized, approximately 0.53 V cathodic shift of the hematite film. Working mechanisms were investigated from both kinetic and thermodynamic ways. The ultrathin Ti-doped Fe₂O₃ film exhibited reduced Tafel slope and higher generated photovoltage than the pristine Fe₂O₃ electrode. Moreover, the highly doped Fe₂O₃ resulted in significant reduction of charge-transfer resistance at the Fe₂O₃∥electrolyte interface. The drastic cathodic-shift <i>V</i>_on is believed to be a result of combined factors including thermodynamic contribution, improved surface reaction kinetics, as well as facilitated charge transfer across bulk and interface

Anchoring Tailored Low-Index Faceted BiOBr Nanoplates onto TiO₂ Nanorods to Enhance the Stability and Visible-Light-Driven Catalytic Activity

In this work, a fantastic one-dimensional (1D) BiOBr/TiO₂ nanorod (NR) heterojunction composite was rationally proposed and designed from the perspective of molecular and interface engineering. The fabricated intimately connected interfacial heterojunction between two-dimensional BiOBr nanoplates and 1D TiO₂ NRs acts as an interfacial nanochannel to promote efficient interfacial charge migration and separation of photogenerated electron–hole pairs. As a result, 1D BiOBr/TiO₂ NR heterojunctions exhibited outstanding visible-light photocatalytic activities and sustained cycling performance. Under visible-light irradiation for 120 min, the reduction efficiency of Cr­(VI) over the TB-2 sample (molar ratio: <i>n</i>(Ti)/<i>n</i>(Bi) = 2:1) is as high as 95.4% without adding any scavengers. Furthermore, the sample also shows excellent photodegradation activity of RhB with a much higher apparent rate constant of 0.49 min^–1 and 88.5% total organic carbon removal ratio. Furthermore, the corresponding mechanism of enhanced photocatalytic activity is proposed according to comprehensively investigated results from photoluminescence spectroscopy, photoelectrochemical measurement analysis, and radical trapping experiments. This study provides an attractive avenue to design and fabricate highly efficient 1D NR heterojunction photocatalysts, which possessed a high application value in the field of environmental remediation, especially for wastewater purification

Construction of High-Quality SnO₂@MoS₂ Nanohybrids for Promising Photoelectrocatalytic Applications

High-quality three-dimensional (3D) hierarchical SnO₂@MoS₂ nanohybrids were successfully obtained via a facile but effective wet chemistry synthesis method. Meanwhile, the SnO₂@MoS₂ hybrid film was fabricated through an electrophoretic deposition method to promote photoelectrocatalytic (PEC) efficiency and solve the recovery problem. Compared with the pure SnO₂ and MoS₂ films, the SnO₂@MoS₂ heterostructures could decrease the rate of the photoelectron–hole pair’s recombination, which resulted in the superior PEC pollutant degradation and water splitting activities. Meanwhile, the SnO₂@MoS₂ hybrid films with well-defined 3D hierarchical configurations have large surface areas, abundant active edge sites, and defects on the basal surfaces, which were also advantageous for the PEC activities (for pollutant degradation, apparent rate constant <i>k</i> = 5.91 h^–1; for water splitting, onset potential = −0.05 V and current density = 10 mA/cm²). Therefore, the SnO₂@MoS₂ hybrid film proved to be a superior structure for PEC applications

Enabling All-Solid-State Lithium–Carbon Dioxide Battery Operation in a Wide Temperature Range

Flexible all-solid-state lithium–carbon dioxide batteries (FASSLCBs) are recognized as a next-generation energy storage technology by solving safety and shuttle effect problems. However, the present FASSLCBs rely heavily on high-temperature operation due to sluggish solid–solid–gas multiphase mass transfer and unclear capacity degradation mechanism. Herein, we designed bicontinuous hierarchical porous structures (BCHPSs) for both solid polymer electrolyte and cathode for FASSLCBs to facilitate the mass transfer in all connected directions. The formed large Lewis acidic surface effectively promotes the lithium salt dissociation and the CO2 conversion. Furthermore, it is unraveled that the battery capacity degradation originates from the “dead Li2CO3” formation, which is inhibited by the fast decomposition of Li2CO3. Accordingly, the assembled FASSLCBs exhibit an excellent cycling stability of 133 cycles at 60 °C, which is 2.7 times longer than that without BCHPSs, and the FASSLCBs can be operated repeatedly even at room temperature. This BCHPS method and fundamental deactivation mechanism provide a perspective for designing FASSLCBs with long cycling life

<i>In Situ</i> Formed Ti/Nb Nanocatalysts within a Bimetal 3D MXene Nanostructure Realizing Long Cyclic Lifetime and Faster Kinetic Rates of MgH₂

Magnesium hydride (MGH) is a high-capacity and low-cost hydrogen storage material; however, slow kinetic rates, high dehydrogenation temperature, and short cycle life hindered its large-scale applications. We proposed a strategy of designing novel delaminated 3D bimetal MXene (d-TiNbCTx) nanostructure to solve these problems. The on-set dehydrogenation temperature of MGH@d-TiNbCTx composition was reduced to 150 °C, achieving 7.2 wt % of hydrogen releasing capacity within the range of 150–250 °C. This composition absorbed 7.2 wt % hydrogen within 5 min at 200 °C and 5.5 wt % at 30 °C within 2 h, while the desorption capacity (6.0 wt %) was measured at 275 °C within 7 min. After 150 cycles at 250 °C, the 6.5 wt % capacity was retained with negligible loss of hydrogen content. These results were attributed to the catalytic effect of in situ-formed TiH2/NbH2 nanocatalysts, which lead to dissociate the Mg–H bonds and promote of kinetic rates. This unique structure paves great opportunities for designing of highly efficient MGHs/MXene nanocomposites to improve the hydrogen storage performance of MGHs

Unveiling the Potential of the Alkyl Chain of Isoleucine for Regulating the Electrical Double Layer and Enhancing the Zinc-Ion Battery Performance

Amino acids are considered effective additives for regulating the electric double layer (EDL) in zinc-ion battery (ZIB) electrolytes. In comparison to their polar counterparts, nonpolar amino acids have received less attention in research. We demonstrated that isoleucine (ILE), benefiting from its nonpolar alkyl chain, emerges as a highly suitable electrolyte additive for aqueous ZIBs. ILE molecules preferentially adsorb onto the anode surface of zinc metal, subsequently creating a locally hydrophobic EDL facilitated by the alkyl chain. On one hand, this enhances the thermodynamic stability at the anode, while on the other hand, it accelerates the desolvation process of zinc ions, thereby improving the kinetics. Benefiting from the unique properties of ILE molecules, Cu//Zn cells with the ILE additive ultimately achieved an extended cycle life of 2600 cycles with an average coulombic efficiency of 99.695%, significantly outperforming other amino acid additives reported in the literature

Highly Electrically Conductive Polyiodide Ionic Liquid Cathode for High-Capacity Dual-Plating Zinc–Iodine Batteries

Zinc–iodine batteries are one of the most intriguing types of batteries that offer high energy density and low toxicity. However, the low intrinsic conductivity of iodine, together with high polyiodide solubility in aqueous electrolytes limits the development of high-areal-capacity zinc–iodine batteries with high stability, especially at low current densities. Herein, we proposed a hydrophobic polyiodide ionic liquid as a zinc-ion battery cathode, which successfully activates the iodine redox process by offering 4 orders of magnitude higher intrinsic electrical conductivity and remarkably lower solubility that suppressed the polyiodide shuttle in a dual-plating zinc–iodine cell. By the molecular engineering of the chemical structure of the polyiodide ionic liquid, the electronic conductivity can reach 3.4 × 10–3 S cm–1 with a high Coulombic efficiency of 98.2%. The areal capacity of the zinc–iodine battery can achieve 5.04 mAh cm–2 and stably operate at 3.12 mAh cm–2 for over 990 h. Besides, a laser-scribing designed flexible dual-plating-type microbattery based on a polyiodide ionic liquid cathode also exhibits stable cycling in both a single cell and 4 × 4 integrated cell, which can operate with the polarity-switching model with high stability