The formation processes of barrier anodic alumina (BAA) and porous anodic alumina (PAA) are discussed in detail. The anodizing current J(T) within the oxide includes ionic current j(ion) and electronic current j(e) during the anodizing process. The j(ion) is used to form an oxide and the j(e) is used to give rise to oxygen gas or sparking. The j(e) results from the impurity centers within the oxide. For a given electrolyte, the j(e) is dependent on the impurity centers and independent of the J(T). The formation of nanopores can be ascribed to the oxygen evolution within the oxide. Oxygen gas will begin to be released at the critical thickness d(c). The manner of the development of PAA is in accordance with that of BAA. The differences between PAA and BAA are the magnitude of j(e) or the continuity of oxygen evolution. There are two competitive reactions, i.e. oxide growth (2Al3 + 3O2- --> Al2O3) and oxygen evolution (2O2- --> O2 up arrow + 4e). The former keeps the wall of the channel lengthened, the latter keeps the channel open. By controlling the release rate of oxygen gas under different pressures, the shape of the channels can be adjusted. The present results may open up some opportunities for fabricating special templates.

Ferromagnetic Mn5Ge3 thin films were grown on Ge(111) with solid-phase epitaxy. The epitaxial relationship between the alloy film and substrate is Mn5Ge3(001)//Ge(111) with [100]Mn5Ge3//[11̄0]Ge. The alloy films exhibit metallic conductivity and strong ferromagnetism up to the Curie temperature, TC=296 K. These epitaxial alloy films are promising candidates for germanium-based spintronics.

Currently, Pt single atoms as promising electrocatalysts have been applied to electrocatalysis aiming to significantly improve performance and remarkably lower usage of the noble metal. Herein, we propose a photochemical solid-phase reduction method to fabricate well-defined isolated Pt atoms on a nitrogen-doped porous carbon (Pt1/NPC). Using this simple and fast synthesis strategy, the formed Pt atoms are well-dispersed on the carbon without clusters or nanoparticles. The loading of the Pt is up to 3.8 wt % relative to the carbon. The Pt1/NPC catalyst displays an ultrahigh electrocatalytic activity for hydrogen evolution reaction with an overpotential of 25 mV at the current density of 10 mA cm–2 and mass activity of 2.86 A mg–1 Pt (24-times higher than a commercial Pt/C). Moreover, the catalyst also presents efficient catalytic activity for the oxygen reduction reaction. Its mass activity is 4.3-times that obtained by a commercial Pt (20 wt %). The improved electrocatalytic activities of the Pt1/NPC catalyst are ascribed to the favorable chemical and electronic structure of the Pt–N4 coordination raised by strong electron transfer from the isolated Pt atoms to the coordinated N atoms in this catalyst. The Pt1/NPC can be employed as a bifunctional catalyst for fuel cells and hydrogen production.

An organic–inorganic based surface film was formed on a 5 V-class LiNi0.5Mn1.5O4 cathode by tris(trimethylsilyl)phosphite (TMSP). This surface-modified cathode exhibited significantly improved electrochemical properties in terms of cycling stability and rate capability.

Anodic TiO 2 nanotubes (NTs) have been studied extensively for many years. However, the growth kinetics still remains unclear, because it is hardly derived by direct in situ methods. Here, an interesting approach is proposed to overcome this challenge. A combinatorial anodization was exploited to monitor the pore initiation and nanotube growth under a preformed compact surface layer (CSL). The preformed CSL and the NTs under the CSL (UCSL-NTs) were formed in fluoride-free and fluoride-containing electrolytes, respectively. The forming process of UCSL-NTs was discussed as compared with that of the general NTs, mainly focusing on the differences of current-time curves and electric charge quantity (Coulomb). The results show that pore embryos of UCSL-NTs have already been achieved under the CSL before the CSL is dissolved. There are five stages in the current-time curve of UCSL-NTs, which is significantly different from three stages of the general NTs. A new growth model, based on a comprehensive review of the existing theories, is proposed to explain the current decrease and increase. And the forming process of TiO 2 NTs is considered to be dominated by the oxide plastic flow around the oxygen bubbles.Anodic TiO 2 nanotubes (NTs) and other porous anodic oxides have attracted considerable scientific interests due to their various applications (e.g., solar energy materials, magnetic semiconductors and biosensors) 1-3 and mysterious formation mechanisms. 4,5 Different mechanisms of TiO 2 NTs have been reported in many electrochemical journals in recent years. 4-8 It is well known that field-assisted dissolution (FAD) (TiO 2 + 6F − + 4H + → [TiF 6 ] 2− + 2H 2 O) of the oxide leads to pore formation in anodic titania films, 8-10 similar to that in porous anodic alumina (PAA) films (Al 2 O 3 + 6H + → 2Al 3 + + 3H 2 O), 11-14 despite a lack of direct experimental evidence that confirms this expectation. 14 As the formation mechanism is impossible to be derived by direct in situ experimental methods, much remains to be done along these directions. 15 Garcia-Vergara et al. 16,17 proposed the field-assisted 'plastic flow' model, the constant thickness of the barrier layer is maintained by flow of oxide from the pore bottom toward the pore wall, driven by compressive stresses from electrostriction and possibly through volume expansion. 16 In fact, the plastic flow is contrary to expectations of the FAD. 16 The behavior of incorporated species in PAA is always incompatible with the FAD model. 16 The flow model has been recognized and exploited for explaining the formation of TiO 2 NTs and serrated nanochannels. 18,19 However, Zhou et al. 12 indicated that both the FAD and the flow models cannot explain the formation of gaps among nanotubes. In recent tracer studies on Ti thin films, the expansion factors increase from 1.5 to 3.0, 20,21 these findings cannot be clarified. Furthermore, anodized TiO 2 NTs have been achieved in an aqueous H 2 SO 4 solution as well as other fluoride free solutions, 12,22,23 this fact puts the flu...