SnO2 is widely used in perovskite solar cells(PSCs)due to its high electron mobility,suitable conduction band and low-temperature preparation characteristics.Currently,the two most commonly used methods for preparing SnO2 are SnCl2 hydrolysis oxidation or SnO2 sol-gel preparation.However,although SnCl2 hydrolysis oxidation can produce well-crystallized SnO2,its controllability is poor,resulting in low device performance repeat-ability.On the other hand,the devices based on SnO2 electronic transport layer prepared by the sol-gel method have good repeatability,but usually have poor crystallinity,leading to a decrease in electron transport performance.In this study,a combination of hydrolysis oxidation and sol-gel methods was used to prepare SnO2 electronic transport layers.The results of the study demonstrate that using SnCl2 hydrolysis oxidation to prepare high-quality SnO2 crystalline layers can serve as a pre-growth template to improve the crystalline quality of sol-gel generated SnO2.Additionally,covering the hydrolysis oxidation-based SnO2 layer with sol-gel prepared SnO2 crystalline layer can improves the repeatability of device preparation.The electron transport layers prepared by this method can effectively enhance the quality of thin film crystal growth and charge extraction capability,ultimately contributing to improving the efficiency,stability,and reducing hysteresis of the devices.
TiNi shape memory alloys have clear target demand in a variety of fields owing to their excellent struc-tural and functional properties.In this paper,focusing on B2 structural austenitic Ni-rich TiNi alloys,it is proposed to modulate the microstructure of the TiNi alloys through repeated cold rolling annealing,with an expectation to enhancing the lower mechanical strength and plastic deformation ability of the alloys.The dependence of the mechanical properties and microstructure of Ti48.9Ni50.9Zr0.2 and Ti47.9Ni51.9Zr0.2 alloys on cold rolling deformation and recrystallization annealing was systematically investigated.The tensile mechanical property tests show that the repeated cold rolling annealing can significantly enhance the overall mechanical properties of the alloys,in which the tensile strength of Ti48.9Ni50.9Zr0.2 alloy is increased from 550 MPa in the unrolled samples to 1 070 MPa after 6 passes of cold rolling annealing,and the elongation after fracture has grown from 4.9％to 10.0％.The EBSD,SEM and TEM microstructural observation reveals that the deformation and recrystallization structures of the alloy change alternately after multi-pass cold rolling and annealing,and the alloy grains are significantly refined and undergo an obvious preferred grain orientation.In addition,the basal texture of the alloy is further enhanced.The Ti2Ni and Ti3Ni4 precipitates are broken and refined during cold deformation,in which the nano-sized Ti3Ni4 pre-cipitate exhibits a favorable matching with matrix.Furthermore,stress-induced martensite as well as a large num-ber of high-density dislocations in the vicinity of the precipitation phases appear in the alloy.The mechanical pro-perties of alloys are strongly related to the microstructure,and the strengthening mechanisms can be understood by grain refinement strengthening,dislocation strengthening,precipitation strengthening and texture strengthening.
The light and high strength bamboo scrimber was buried in the core of concrete-filled steel tube (CFST) to form bamboo scrimber and concrete-filled steel tube column (BCFST), which was expected to reduce the amount of concrete and weight in CFST and promote the use of bamboo scrimber. To investigate the influences of key design parameters on the compressive performance, namely bamboo scrimber dimension, design concrete strength, and diameter to thickness of steel tube, ninety BCFSTs and eighteen CFSTs specimens were tested under axial compression. According to the experimental results, the improvement of the BCFST bearing capacity resulted from the contribution of the inner sandwich concrete and the bamboo scrimber under the constraint from the steel tube. The ultimate load rose with the increase of the bamboo scrimber dimension, concrete strength, and steel tube thickness. Note that the increase range of ultimate load of BCFSTs is 3.9% higher than that of CFSTs by increasing the dimension of bamboo scrimber, with a maximum increase at 43.9%. The damage modes of BCFSTs can generally be categorized into local buckling failure mode and shear failure mode. In addition, owing to the different compactness between the bamboo scrimber and the concrete, the stress-strain curve of the C80 concrete characterized the strain hardening tendency rather than the strain softening tendency in the C50 concrete. According to the load-strain curves of the BCFSTs and the contribution of the composite actions between the three parts of the member to the load-carrying capacity, the characteristic points were defined. A calculation model for accurately predicting the ultimate capacity of BCFSTs was proposed by considering the boundary conditions for both non built-in and fully built-in bamboo scrimber in CFSTs.
A series of Cu-BTC with different Polyvinylpyrrolidone (PVP) assisted amounts were pyrolyzed to prepare carbon supported copper and its oxides (CuOx/C without PVP and CuOx@PC with PVP) derivant. The structure of CuBTC and derivant was characterized by XRD, SEM, TEM, N2 adsorption isotherms et al., and the derivant was applied for oxidative carbonylation of methanol to dimethyl carbonate. The results show that the introduction of PVP is beneficial to improve the specific surface area of CuOx@PC and generate Cu-Cu2O heterojunctions. The activities of the catalysts containing Cu-Cu2O heterojunctions are higher than that of the catalysts without Cu-Cu2O. Compared with CuOx/C, the space-time yield of CuOx@PC-2 of dimethyl carbonate is significantly enhanced from 948 mg g-1 h-1 to 1295 mg g-1 h-1. Cu-Cu2O has a synergistic effect on the catalytic performance. The stability of the catalysts was evaluated. After eight cycles, the deactivation rate of CuOx@PC-2 (53 %) is lower than that of CuOx/C (74 %), because the aggregation of Cu is inhibited by the introduction of PVP. And the oxidation of Cu species is mainly responsible for the deactivation of the catalysts.
Hydrogel-based flexible polymer materials have received increasing attention due to their excellent sens-ing performance and superior ductility with application in smart wearable devices.However,the widespread use of intelligent wireless electronic wearables equipment has also produced severe electrical signals interference and ra-diation.The electrical signals interference generated by wearable devices significantly affects the performance of apparatuses.Therefore,it is important to develop hydrogel materials with dual functions of strain sensing and elec-tromagnetic shielding.This review begins with presenting on strain sensing and electromagnetic shielding mechan-ism of hydrogel materials.At the same time,the effects of microstructure,solvent type,conductive filler type and conductive network structure on the properties of bifunctional hydrogel materials are analyzed.Finally,according to the current research status of bifunctional hydrogels,the development direction and application prospect of bi-functional hydrogels are proposed.
