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Graphene oxide (GO) is a two‐dimensional material known for its exceptional mechanical, chemical and electrical characteristics. Here, the mechanical properties and functionalization of GO reinforced thermoplastic polyurethane (TPU) polymer composites with GO content ranging from low to high were investigated. It shows that the GO can mix with TPU in any proportion. The microstructure changed from disorder arrangement to a regular nacre‐like staggered structure, accompanied by different kinds of internal defects as the content increases, resulting in multiple peaks in the tensile properties of composite materials. The tensile strength of composites containing 80 wt% GO is 194% higher than that of pure TPU. This result is closely related to the changes in internal microstructure arrangement, the corresponding stress distribution and the transformation of damage mechanisms. Simultaneously, it shows that the composites exhibited shape memory function at low GO content of 1.5 wt% with about 100% shape recovery at 70°C, and electrical conductivity and deicing function at high GO content of 80 wt% after chemical reduction, which can reach a temperature of 107°C at 10 V AC. These findings will help to comprehensively understand the structural and functional integration design of GO reinforced polymer composites. Highlights: Mechanical properties and functionalization of GO/TPU composites were studied.Increased GO causes the arrangement to change from disorder to a nacre‐like structure.Stress distribution and damage mechanisms transformed as the GO content changed.The GO/TPU composites exhibited shape memory and deicing function. [ABSTRACT FROM AUTHOR]

A RVE finite element model was developed, and the effective mechanical properties were predicted by analyzing the fine structure of Z‐pin reinforced composite laminates. A new damage criterion based on strain description is adopted, a progressive damage analysis model is established and progressive damage analysis is carried out, which provides a reference for further research on Z‐pin reinforced composites. By applying both longitudinal tensile and in‐plane shear loads to the RVE, the material strength prediction was carried out the damage evolution process was emphasized, and the stress–strain curves of the material as well as the damage modes and damage levels in different regions were finally predicted. From the damage evolution process, it can be seen that the damage in the fiber direction and the damage in the transverse direction appear the earliest and have the highest percentage of failure. Highlights: The RVE model was developed and its effective mechanical properties were predicted.A new damage criterion is introduced, a UMAT subroutine is written, and a progressive damage model is developed.Material strength predictions were made for the RVE and the damage evolution process was emphasized. [ABSTRACT FROM AUTHOR]

Nanoparticles are prone to aggregation in the matrix under the action of surface energy, chemical bonding, electrostatic attraction, and van der Waals forces. Based on the molecular dynamics method, the tensile properties of graphene oxide (GO)‐reinforced nylon 66 composites were simulated and calculated, and the stress–strain curves, atomic stress clouds, and changes in the number of hydrogen bonds were obtained for the composites under tensile loading, and the effects of GO agglomeration on the mechanical properties of GO/PA66 composites were analyzed. When the GO mass fraction accounted for 90.3%, 80.5%, and 70.6% of the model, respectively, the mechanical properties of the composites decreased by 15.4%, 4.5%, and 4.2%, respectively. Because GO agglomeration in the composites made it difficult to bond effectively between GO and PA66, the number of hydrogen bonds and the type of hydrogen bonds within the model, varied with the degree of aggregation. The changes in the number of hydrogen bonds and the type of hydrogen bonds during uniaxial stretching were simulated by molecular dynamics. The number of hydrogen bonds and the type of hydrogen bonds directly affect the mechanical properties of the composites. It can be seen from the atomic stress cloud diagram that the aggregation of GO makes the mechanical properties of GO fail to exert effectively. The main stress is on the C atoms in the outermost layer of GO, while the stress on the inner layer C atoms is relatively small. As the degree of GO agglomeration decreases, the stress on each C atom of GO lamellae tends to be uniform, which effectively brings into play the excellent mechanical properties of GO and improves the mechanical properties of the composite. [ABSTRACT FROM AUTHOR]

In general, an increase in O2 adsorption is highly desirable for efficient photocatalysis. Herein, commercial P25 TiO2 is modified with an F127-containing SiO2 sol, and post-treated with phosphoric acid. It is confirmed, on the basis of O2 temperature-programmed desorption measurements, that the O2 adsorption of commercial P25 TiO2 is greatly promoted through its modification with porous SiO2, especially in the phosphate-treated case. The promotion of O2 adsorption is attributed to the introduction of SiOH and POH as surface ends, and to the slightly increased surface area. Interestingly, it is concluded that the promotion of O2 adsorption is favorable for the separation of photogenerated charge carriers, as seen from the steady-state surface photovoltage spectra, transient-state surface photovoltage responses, and measurements of the hydroxyl radicals produced. This is responsible for the clear enhancement in the photocatalytic activity of modified TiO2 for the degradation of gas-phase acetaldehyde and liquid-phase phenol as colorless pollutants. This work provides a feasible route for improving the photocatalytic activity of TiO2. [ABSTRACT FROM AUTHOR]

In general, an increase in O2 adsorption is highly desirable for efficient photocatalysis. Herein, commercial P25 TiO2 is modified with an F127-containing SiO2 sol, and post-treated with phosphoric acid. It is confirmed, on the basis of O2 temperature-programmed desorption measurements, that the O2 adsorption of commercial P25 TiO2 is greatly promoted through its modification with porous SiO2, especially in the phosphate-treated case. The promotion of O2 adsorption is attributed to the introduction of SiOH and POH as surface ends, and to the slightly increased surface area. Interestingly, it is concluded that the promotion of O2 adsorption is favorable for the separation of photogenerated charge carriers, as seen from the steady-state surface photovoltage spectra, transient-state surface photovoltage responses, and measurements of the hydroxyl radicals produced. This is responsible for the clear enhancement in the photocatalytic activity of modified TiO2 for the degradation of gas-phase acetaldehyde and liquid-phase phenol as colorless pollutants. This work provides a feasible route for improving the photocatalytic activity of TiO2. [ABSTRACT FROM AUTHOR]

N-doped nanocrystalline TiO2 is synthesized successfully through a simple ammonia-modified hydrolysis-solvothermal process. It is demonstrated that the resulting TiO2 doped with an appropriate amount of N exhibits high visible photocatalytic activities for the degradation of gas-phase acetaldehyde and liquid-phase phenol, which is attributed to its increased visible adsorption, appropriate crystallinity, and good dispersibility, whereas its UV activity is decreased. On the basis of the atmosphere-controlled surface photovoltage spectra, it is found that the doped N species can capture the photogenerated holes so as to be favorable for photogenerated charge separation, so it is suggested that its decreased UV activity results from its weak adsorption of O2 compared with that of undoped TiO2, as shown by the O2 temperature-programed desorption curves. Interestingly, the photocatalytic activity of the resulting N-doped TiO2 under visible or UV irradiation can be improved further by promoting O2 adsorption after modification with an appropriate amount of phosphoric acid. [ABSTRACT FROM AUTHOR]

In this work, commercial P25 TiO2 is modulated by post-treatments with different acidic substances, and the effects of residual acidic substances on the photogenerated charge separation of TiO2 and its photocatalytic activity are investigated in detail. It is demonstrated by means of atmosphere-controlled surface photovoltage spectroscopy that an increase in acid surface modification is favorable for improving the photogenerated charge separation of TiO2. As a result, its photocatalytic activity for the degradation of gas-phase acetaldehyde is enhanced greatly. On the basis of measurements of O2 temperature-programmed desorption of untreated and treated TiO2, it is confirmed that an increased amount of acid surface modification promotes the adsorption of O2 on TiO2. Hence, it is suggested for the first time that an increase in surface acidity through post-treatment with an appropriate amount of acidic substance leads to a clear enhancement of the photocatalytic activity of TiO2 by promoting O2 adsorption, and thus, improving the photogenerated charge separation of TiO2. This work provides a feasible route for the synthesis of high-activity oxide-based semiconductor photocatalysts through surface modification with stable inorganic acids. [ABSTRACT FROM AUTHOR]

Effectively contacted multiwalled carbon nanotube (MWCNT)-titanium dioxide nanocomposites and phosphate-functionalized MWCNT-TiO2 composites have been successfully synthesized by simple one-pot phase-separated hydrolysis-solvothermal processes. The key to this synthetic strategy is to disperse MWCNTs uniformly in Ti(OBu)4 in advance and then to put them into the toluene organic phase. The as-prepared nanocomposites between TiO2 and the correct amount of MWCNT exhibits higher activity in the photocatalytic degradation of rhodamine B than that with the resulting TiO2, although the activity in the photocatalytic degradation of gas-phase aldehyde and liquid-phase phenol is lower. Interestingly, the functionalization of MWCNTs with an appropriate amount of phosphoric acids prior to the synthesis could greatly improve the activity of the MWCNT-TiO2 nanocomposites for the degradation of aldehyde and phenol, even superior to that of commercial P25 TiO2. Based on the measurements of atmosphere-controlled surface photovoltage spectra and O2 temperature-programmed desorption, it is suggested that MWCNTs are favorable to increase rhodamine B adsorption on the composite to promote the photosensitization oxidation reactions, whereas it is unfavorable for the adsorption of O2 and responsible for the low photocatalytic activity for the degradation of colorless pollutants. Phosphate functionalization greatly enhances the amount of O2 adsorbed on the MWCNT, which leads to significant charge separation, and thus, to significant photoactivity for the degradation of colored and colorless pollutants of the nanocomposites. [ABSTRACT FROM AUTHOR]

In this work, commercial P25 TiO2 is modulated by post-treatments with different acidic substances, and the effects of residual acidic substances on the photogenerated charge separation of TiO2 and its photocatalytic activity are investigated in detail. It is demonstrated by means of atmosphere-controlled surface photovoltage spectroscopy that an increase in acid surface modification is favorable for improving the photogenerated charge separation of TiO2. As a result, its photocatalytic activity for the degradation of gas-phase acetaldehyde is enhanced greatly. On the basis of measurements of O2 temperature-programmed desorption of untreated and treated TiO2, it is confirmed that an increased amount of acid surface modification promotes the adsorption of O2 on TiO2. Hence, it is suggested for the first time that an increase in surface acidity through post-treatment with an appropriate amount of acidic substance leads to a clear enhancement of the photocatalytic activity of TiO2 by promoting O2 adsorption, and thus, improving the photogenerated charge separation of TiO2. This work provides a feasible route for the synthesis of high-activity oxide-based semiconductor photocatalysts through surface modification with stable inorganic acids. [ABSTRACT FROM AUTHOR]