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[Display omitted] • Passive film composition changes during long-term passivation of Ni-Cr-X alloys. • Cr enriches in film and Ni enriches at the metal/film interface with time. • Aliovalent Mo and W enrichment in passive films occurs during Cr(III) enrichment. • Corundum forms early, while spinel forms over time by phase transformation. • The applied passivation potential and time influence spinel protectiveness. The passivation of Ni-22Cr, Ni-22Cr-6Mo, and Ni-22Cr-6Mo-3W (wt%) was characterized from 100 s to 10 days in 0.1 M NaCl in pH 4 at various potentials in the passive range. The influence of aqueous solution exposure time in NaCl (exposure aging), passivation potential, as well as Ni-Cr-X alloy composition (Mo or W) on passive film growth, composition, oxidation state, molecular identity, and inner versus outer film layering were investigated. Initial passive film formation was dominated by Ni(II). Cr(III) oxides and hydroxides tended to enrich upon formation and exposure aging. Corundum and rock salt are speculated to undergo a solid-state phase transformation to form NiCr 2 O 4 at long times under certain conditions. The concept of the time-potential-transformation diagrams to describe the evolution of passive film phases and protectiveness is introduced. Factors limiting Cr(III) enrichment were discussed. Aliovalent Mo and W ions were detected in passive films, particularly after aging. The roles of Cr enrichment, Ni depletion, and Mo and/or W aliovalent cations after oxide aging towards protectiveness to passive and localized corrosion in chloride (Cl-) solutions were discussed. [ABSTRACT FROM AUTHOR]

We obtained three types of particles with different surface characteristics, including solid silica with smooth surface and no surface group (SiO 2), mesoporous silica with rough surface and no surface group (M−SiO 2) and mesoporous silica with rough surface and surface silicon hydroxyl groups (M−SiO 2 (–OH)). Compared with SiO 2 , M−SiO 2 and M−SiO 2 (–OH) have higher friction between particles due to rough surfaces, and there is adhesion force between M−SiO 2 (–OH) particles due to the presence of hydroxyl groups on the surface. The schematic phase diagram of the ϕ - γ ̇ for three types of particles shows the difference of rheological property. [Display omitted] • The influence of surface characteristics on the suspensions was explored. • The roles of friction and adhesion forces on the suspensions were evaluated. • The ϕ - γ ̇ phase diagram was present to demonstrate the rheological difference. The surface characteristic of suspended nanoparticle is an extremely important property for the non-Newtonian behavior of shear thickening suspensions. Easy access to distinct surface characteristics and a deep understanding of the role of friction and adhesion forces remains challenging yet critical to study the suspension performance. In this work, by synthesizing mesoporous silica with different surface roughness and groups, the influence of surface characteristics on the non-Newtonian behavior of suspension is comprehensively explored. The results show that the suspensions containing particles with rough surface and hydroxyl groups on the surface have higher shear thickening power, lower critical shear rate, lower discontinuous shear thickening transition fraction and lower jamming fraction. Furthermore, the test of the first normal stress difference N 1 shows that the interparticle friction and adhesion both reduce the critical volume fraction of the transition from fluid lubrication dominance to frictional contact dominance in the suspension. This finding deepens the understanding of phase transformation mechanism, and open an approach to accelerate the advanced shear thickening suspensions design for next-generation intelligent materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu-HEO heterostructures were constructed by using Cu-containing HEO precursors. • Effects of Cu adding methods on Cu NPs size and activity of Cu-HEO were investigated. • The diffusion hysteresis effect of HEO was favor for the formation smaller Cu NPs. • Cu 0.5 -HEO shows superb photocatalytic activity and CH 4 selectivity for CO 2 reduction. The construction of metal–semiconductor heterojunction has been proven to be an effective way to improve the separation efficiency of photogenerated electrons and holes, thus enhancing photocatalytic activity of semiconductor with narrow band gap. Here, we construct a Cu-(Ga 0.2 Cr 0.2 Mn 0.2 Ni 0.2 Zn 0.2) 3 O 4 high entropy oxide (HEO) heterojunction by using Cu-containing HEO precursor, and the effect of Cu addition method on the photocatalytic performance was investigated. The results show that the addition method of Cu has a great influence on the size of Cu nanoparticles (NPs), heterojunction amount and photocatalytic activity of Cu-HEO catalysts. Cu-HEO samples prepared by direct introduction method possess much smaller Cu particles due to the uniform distribution and stronger diffusion hysteresis effect of Cu in HEO, and exhibit superior photocatalytic activity and CH 4 selectivity for CO 2 reduction. With the increase of Cu loading, the photocatalytic activity of Cu-HEO samples firstly increases and then decreases. Among these photocatalysts, Cu 0.5 -HEO obtained by the direct introduction method displays the highest CO 2 reduction activity, and the yields of CO and CH 4 reach to 5.66 and 33.84 µmol/h/g cat , respectively. This work innovatively uses HEO precursors with unique properties to construct metal-HEO heterojunctions with smaller metal particles and more active sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hierarchical heterostructure is fabricated by incorporating the TiO 2 or SiO 2 into the Fe 3 O 4 micro-flower framework. • Adjusting the content of TiO 2 and SiO 2 can effectively regulate the impedance matching. • An extremely broad effective absorption of 7.3 GHz can be achieved at a single thickness of only 2.0 mm for Fe 3 O 4 /TiO 2. Rational design of hierarchical heterogeneous structured Fe 3 O 4 toward boosted electromagnetic wave absorption (EMA) is extremely imperative and needs further exploration. In this study, we use two types of dielectric components, including TiO 2 and SiO 2 particles, as intercalations anchor in Fe 3 O 4 micro-flower framework through a sol–gel process to construct hierarchical hetero-structures. The tunable contents of anchoring particles allow the composites to retain their micro-flower structure and enable a reinforced polarization loss as well as enhanced impedance matching. As a result, both Fe 3 O 4 /TiO 2 and Fe 3 O 4 /SiO 2 exhibit excellent EMA performance. In detail, the Ti-2 possesses an effective absorption bandwidth (EAB) of 7.3 GHz (9.3–16.6 GHz) at 2.0 mm and a reflection loss (RL) of −67.1 dB at 3.78 mm. Si-2 exhibits a strong absorption with RL of −59.1 dB at 2.35 mm and an EAB of 4.8 GHz (8.3–13.1 GHz) at 2.0 mm. More importantly, an in-depth analysis confirms that the EMA of Ti-2 is superior to the previously reported results in terms of EAB, matching thickness, and absorption intensity. Therefore, this work provides a novel pathway to fabricate high-performance EMA absorbers via rational design of hierarchical hetero-structure. [ABSTRACT FROM AUTHOR]