Oxygen-Vacancy-Mediated Large Binding Energy Exciton Dissociation in Nb3O7(OH) Nanorods with High Electron Mobility for CO2 Photoreduction.

Despite the excellent performance of Nb3O7(OH) in dye-sensitized solar cells and catalysis, its charge separation, transport, and structural properties remain poorly understood. Herein, the Nb3O7(OH) nanorods were prepared, and their structural characteristics, optoelectronic properties, and carrier mobility were also analyzed and investigated through a series of complex characterizations. Theoretical prediction suggested that the exciton binding energy of Nb3O7(OH) could be as high as 100.49 meV. The temperature-dependent photoluminescence (PL) of Nb3O7(OH) nanorods revealed two activation energies, and a higher proportion of long-lived components observed in the photoluminescence decay indicated effective electron trapping. That is, two energy states were present, hindering photogenerated charge recombination and promoting photocatalytic action. Current-voltage characteristics of the Nb3O7(OH) nanorod film were analyzed, revealing an ultrahigh carrier mobility of ∼310 cm2/V·s, ensuring fast and efficient electron transfer. Furthermore, Nb3O7(OH) nanorods were employed to reduce CO2, resulting in the effective production of CO and CH4. Overall, considering the presence of hydroxyl pairs on the surface of Nb3O7(OH), which facilitate the formation of the frustrated Lewis acid-base pairs and the activation of CO2, together with its effective electron trapping and charge transport, give Nb3O7(OH) nanorods a promising potential for CO2 reduction.

Transmission Mechanism and Logical Operation of Graphene-Doped Poly(vinyl alcohol) Composite-Based Memristor.

Memristors are considered the best candidates for nonvolatile memory and advanced computing technologies, and polymer and two-dimensional (2D) materials have been developed as functional layer materials in memristors with high-performance resistive switching characteristics. In this work, a polymer memristor with a graphene (Gr)-doped poly(vinyl alcohol) (PVA) composite acting as the functional layer was prepared. The memristor device exhibited superior performance with good retention and a comparatively large ON/OFF ratio at room temperature. Additionally, excellent logic operations were achieved. These satisfactory properties can be attributed to trap-induced carrier trapping and detrapping. In addition, the device exhibited stable bipolar resistive switching behavior over a moderate temperature range. This work provides insight into the transmission mechanism of polymer-based memristors and the reasons why they become unstable at high temperatures, demonstrating the potential applications of PVA-Gr-based polymer memristors as logic circuit units in integrated chips and artificial intelligence.

In-Depth Investigation of the Mechanism of Dehydration-Induced Phase Transformation from Nb3O7(OH) to H-Nb2O5: A Theoretical and Experimental Approach.

H-Nb2O5 is a promising energy material, which can be typically obtained from any other polymorph after conducting high temperature calcination (∼1273 K). Recently, a low-temperature dehydration from Nb3O7(OH) was employed to prepare H-Nb2O5 at 723 K for 2 h, and yet the transformation mechanism has remained unclear in the literature. Here, the dehydration kinetic and phase transformation mechanism of the Nb3O7(OH) were investigated for the first time by experiments, density functional theory, and molecular dynamics calculations. After dehydration, the orthorhombic Nb3O7(OH) initially transformed into an intermediate Nb-O compound with dislocations, preserving parent structure, and subsequently transformed into monoclinic H-Nb2O5. The activation energy for the transformation from Nb3O7(OH) to H-Nb2O5 was as low as 1.35 eV, compared to that of T-Nb2O5 to H-Nb2O5 (3.60 eV). Furthermore, the defect-rich H-Nb2O5 obtained from Nb3O7(OH), does not exhibit pristine bound exciton state due to severe recombination of photogenerated carriers, resulting in poor photocatalytic activity.

Construction of Superhydrophobic Coating on Iron Surface with Enhanced Anti-Corrosion, Anti-Adhesive and Anti-Bacterial Properties.

Superhydrophobic coatings on iron surface have a wide application potential in medical instruments, chemical industrial equipment, and house construction. In this work, we developed a multi-functional superhydrophobic coating on iron surface with a high air/water contact angle of 162.3° and a low sliding angle of 2.4°. The construction of superhydrophobic coating involves physical friction processing to fabricate micropatterns and structures, followed by annealing treatment and surface chemical modification with 1H,1H,2H,2H-tridecafluoro-n-octyltrimethoxysilane. The obtained organic-inorganic composite material exhibited considerable optimization potential to anti-condensation performance. The low surface energy of the superhydrophobic coating also leads to poor adhesion of water, dust, and blood platelets, which is beneficial for applications in medical devices. The electrochemical and impedance test results demonstrated that the superhydrophobic surface provided effective corrosion protection for the iron substrate, with an 84.63% increase in corrosion protection efficiency. The experimental results showed that the anti-bacterial ratios reached 90% for E. coli and 85% for S. epidermidis, while the anti-bacterial ratios of ordinary iron were only 8% for E. coli and 15% for S. epidermidis, respectively.