Study on the Adsorption Deformation of a Substrate via Spin Coating Based on the 3D-DIC Method and Its Effect on the Homogeneity of Perovskite Films.

The physical and chemical stability of perovskite films has always been a key issue for their industrialization, which has been extensively studied in terms of materials, environment, and encapsulation. Spin coating is one of the most commonly used methods for the preparation of perovskite films in research. However, little attention has been paid to the deformation state of the substrate when it is fixed by means of adsorption and its impact. In this work, the three-dimensional digital image correlation (3D-DIC) method and hyperspectral technology are used to acquire and analyze the adsorption deformation characteristics of the substrate during spin coating, as well as the resulting inhomogeneity. Plastic and four different thicknesses of float glass (0.2, 0.5, 0.7, 1.1 mm) were selected as substrates, and they were tested separately on two suction cups with different structures. The results show that the plastic and 0.2 mm specimens exhibit obvious strain localization behavior. The distribution and magnitude of the strain are affected by the size of the sucker structure, especially the width of the groove. For glass specimens, this effect shows a nonlinear decrease with increasing substrate thickness. Compared to the strain value, the irregularity of local deformation has a greater impact on the non-uniform distribution of materials. Finally, inhomogeneities in the perovskite films were observed through optical lens and hyperspectral data. Obviously, the deformation of the substrate caused by adsorption should attract the attention of researchers, especially for flexible or rigid substrates with low thickness. This may affect the centrifugal diffusion path of the precursor, causing microstructure inhomogeneity and residual stress, etc.

An effective hydroxylation route for a highly sensitive glucose sensor using APTES/GOx functionalized AlGaN/GaN high electron mobility transistor.

A highly sensitive glucose sensor based on AlGaN/GaN high electron mobility transistor (HEMT) has been fabricated. The hydroxyl groups on the GaN surface were achieved by the decomposition of hydrogen peroxide solution (H2O2) under UV irradiation for the production of hydroxyl radicals. The self-assembled monolayers (SAMs) of 3-aminopropyltriethoxysilane (APTES) with terminal amino groups formed on the hydroxylation surface were used as substrates for glucose oxidase (GOx) immobilization. The chemical groups on the GaN surface after hydroxylation were confirmed by X-ray photoelectron spectroscopy. From the analysis of current signals, the biosensor constructed with APTES/GOx exhibited good current response to glucose over a linear range from 10 to 100 µM with a sensitivity of 3.15 × 104 µA mM-1 cm-2 and a detection limit of 10 nM. Meanwhile, the anticipated idea about the hydroxylation of GaN surface, can be an efficient approach for the design of AlGaN/GaN HEMT based biosensors in the future.

Coordination polymer derived general synthesis of multi-shelled hollow metal oxides for lithium-ion batteries.

Multi-shelled hollow metal oxide nanostructures have attracted tremendous attention in energy storage devices owing to their high specific capacity, rate capability and ameliorated cycling performance. Although great progress has been made in synthesizing multi-shelled hollow structures, most methods still depend on tedious template mediated strategies to generate complex interior structures. Herein, we developed a facile universal self-templated approach to synthesize a series of multi-shelled hollow metal oxide spheres with tailored compositions. This strategy involved the solvothermal preparation of uniform spherical coordination polymers (CPs) as precursors and a subsequent thermal treatment in air. Single-, binary- and ternary-metal multi-shelled hollow oxide spheres (Co, Mn-Co, Ni-Co, Ni-Co-Mn, etc.) were successfully obtained. To demonstrate their applications in energy storage, the electrochemical properties of ZnCo2O4 were investigated by testing the lithium-ion-storage performance. Owing to the unique structures, the multi-shelled hollow ZnCo2O4 spheres exhibited high specific capacity, excellent cycling durability (1200 mA h·g-1 after 200 cycles at 0.1 A g-1) and prominent rate capability (730 mA h·g-1 at 5.0 A g-1).

A generalized strategy for the synthesis of two-dimensional metal oxide nanosheets based on a thermoregulated phase transition.

Two-dimensional (2D) metal oxide (MO) nanomaterials, like graphene, possess unique electrical, mechanical, optical and catalytic performances, and have attracted substantial research interest recently. However, it remains a challenge to easily obtain 2D MO nanosheets by a generalized synthetic pathway. Here, we report a general and facile strategy for the synthesis of 2D MO nanosheets induced by nonionic surfactant micelles. Notably, the novel strategy primarily relies on the thermoregulated phase transition of the micelles. The resulting 2D MO nanosheets show high specific surface areas. As a demonstration, Sb2O3 nanosheets synthesized by our method as anodes for sodium-ion batteries (SIBs) have a high reversible capacity of 420 mA h g-1 and a high capacity retention of 99% after 150 cycles at 0.1 A g-1. Mn3O4 nanosheets for supercapacitors have a remarkable specific capacitance of 127 F g-1 at a current density of 0.5 A g-1. Even at a large current density of 5 A g-1 after 10 000 cycles, 96% of the specific capacitance is retained, demonstrating the remarkable performance of these nanosheets for energy storage applications.

A highly selective and sensitive H2S sensor at low temperatures based on Cr-doped α-Fe2O3 nanoparticles.

Cr-doped α-Fe2O3 nanoparticles were synthesized by a low-cost and environmentally friendly hydrothermal route. Their gas sensing properties were investigated and the sensor showed high sensitivity and selectivity to H2S gas. Different Cr doping levels from 0 to 8.0 wt% were studied, and the sensor of 4.0 wt% Cr-doped α-Fe2O3 showed the largest response, with a response of 213 to 50 ppm H2S at 100 °C. The incorporation of Cr ions within α-Fe2O3 nanocrystals increases the specific surface area, and promotes the oxidation of H2S and oxygen adsorption in the air. Thus, the doping of Cr into α-Fe2O3 nanostructures would be a promising method for designing and fabricating high performance H2S gas sensors.