Nitrate is ar aw ingredient for the production of fertilizer,g unpowder,a nd explosives.D eveloping an alternative approach to activate the NNbond of naturally abundant nitrogen to form nitrate under ambient conditions will be of importance.Herein, pothole-rich WO 3 was used to catalyse the activation of N Nc ovalent triple bonds for the direct nitrate synthesis at room temperature.T he pothole-rich structure endues the WO 3 nanosheet more dangling bonds and more easily excited high momentum electrons,w hicho vercome the two major bottlenecks in NNb ond activation, that is,p oor binding of N 2 to catalytic materials and the high energy involved in this reaction. The average rate of nitrate production is as high as 1.92 mg g À1 h À1 under ambient conditions,without any sacrificial agent or precious-metal co-catalysts.M ore generally,t he concepts will initiate an ew pathwayf or triggering inert catalytic reactions.

When cubic PbCrO 3 perovskite (Phase I) is squeezed up to ∼1.6 GPa at room temperature, a previously undetected phase (Phase II) has been observed with a 9.8% volume collapse. Because the structure of Phase II can also be indexed into a cubic perovskite as Phase I, the transition between Phases I and II is a cubic to cubic isostructural transition. Such a transition appears independent of the raw materials and synthesizing methods used for the cubic PbCrO 3 perovskite sample. In contrast to the high-pressure isostructural electronic transition that appears in Ce and SmS, this transition seems not related with any change of electronic state, but it could be possibly related on the abnormally large volume and compressibility of the PbCrO 3 Phase I. The physical mechanism behind this transition and the structural and electronic/magnetic properties of the condensed phases are the interesting issues for future studies.high pressure | X-ray diffraction | DAC | electron state P hase transitions are one of the most fundamental research topics in physics, chemistry, bioscience, and geosciences. Ordinarily, an isostructural phase transition is accomplished with a volume collapse without any symmetrical change. For example, a 6.6% volume change at ∼105 GPa appears during the transition of the B8 structure of MnO due to the Mott transition (1), a 2% volume change at 5.5 GPa occurs in the transition of hexagonal to the same structure ThAl 2 (2), and a 4.0-6.5% volume change appears in the transition of the orthorhombic perovskites of PrFeO 3 , EuFeO 3 , and LuFeO 3 to also orthorhombic structure around 50 GPa (where the transition is considered a high-spin to low-spin transition of the Fe ions) (3). In these transitions, although their axial ratios of both a∕c and b∕c change with their volume at various pressures, the atomic symmetric does not change. In fact, the isostructural phase transitions induced by high pressures are rare and special transitions usually considered to be originating from the electronic structural change in the matter; such a transition appears in cubic Ce (γ-α) and SmS (B1) (4, 5) at room temperature at 0.7 GPa and 0.65 GPa with volume reductions of 15.0% and 13.6%, respectively. Recent evidence suggests that a transition in Ce occurs when the localized f -electron in this system becomes delocalized. Therefore, this transition has been contemporarily referred to as a kind of electronic transition. The volume collapse is therefore considered as a Kondo volume collapse (6). A similar transition appears in Cs, that is, from a face-centered cubic (fcc) phase II to fcc Phase III. It has also been considered as an electronic fcc isostructural transition from 6s to 5d, with a ∼9% volume reduction at around 4.2 GPa (7-9), although recent work has shown that the detailed structure of Phase III is no longer fcc but exactly belongs to a complex large monoclinic (C222 1 ) lattice with 84 atoms (10).Transition-metal oxides with ABO 3 perovskite structure show special properties, such as ferro-electricity, ferro-ma...

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