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In this work, the advantages of in situ loading, heterojunction construction, and facet regulation were integrated based on the poly-facet-exposed BiOCl single crystal, and a facet-oriented supported heterojunction of Cu 2 O and BiOCl was fabricated (Cu 2 O@BiOCl[100]). The photocatalytic nitrogen reduction reaction (pNRR) activity of Cu 2 O@BiOCl[100] was as high as 181.9 μmol·g -1 ·h -1 , which is 4.09, 7.13, and 1.83 times that of Cu 2 O, BiOCl, and Cu 2 O@BiOCl-ran (Cu 2 O randomly supported on BiOCl). Combined with the results of the photodeposition experiment, X-ray photoelectron spectroscopy characterization, and DFT calculation, the mechanism of Cu 2 O@BiOCl[100] for pNRR was discussed. When Cu 2 O directionally loaded on the [100] facet of BiOCl, electrons generated by Cu 2 O will be transmitted to the [100] facet of BiOCl through Z-scheme electron transmission. Due to the directional separation characteristics of charge in BiOCl, the electrons transmitted from Cu 2 O are enriched on the [001] facet of BiOCl, which will together with the original electrons generated by pristine BiOCl act on pNRR, thus greatly improving the activity of photocatalytic ammonia synthesis. Thus, a new construction scheme of biphasic semiconductor heterojunction was proposed, which provides a reference research idea for designing and synthesizing high-performance photocatalysts for nitrogen reduction.

Two-dimensional (2D) materials have a wide range of applications in adsorption and catalysis because of their high specific surface areas and large number of surface active sites. In this paper, bulk ZnAl layered double hydroxides (ZnAl-LDHs or bulk-LDHs) and 2D monolayer ZnAl-LDHs (monolayer-LDHs) were constructed and used for CO 2 capture at temperatures of 298-573 K. The experimental results show that monolayer-LDHs have a large specific surface area (455 m 2 g -1 ) and shows an excellent CO 2 capture performance (4.5 mmol g -1 ). The CO 2 adsorption capacity of monolayer-LDHs decreases greatly with an increase of the temperature, while bulk-LDHs are less affected by the temperature. Moreover, the parameters of charge distribution, density of states, and charge transfer of bulk-LDHs and monolayer-LDHs were studied in detail by density functional theory, and the difference of the adsorption mechanism between two LDH materials in CO 2 capture was compared. It is found that monolayer-LDHs have better electronic activity than bulk-LDHs. At low temperature, CO 2 is more likely to be physically adsorbed on the surface of monolayer-LDHs, and the adsorption process is more likely to occur. CO 2 is more easily adsorbed on the surface of bulk-LDHs in the form of chemisorption, the adsorption energy is larger (-1.01 eV), but the CO 2 capture capacity is quite stable at high temperature.

We report a new in situ synthesis method effective for discovery of high-oxidation-state materials using laser-heated diamond anvil cells. The issue of chemical reduction during thermally induced phase transitions that occur spontaneously in a noble gas pressure transmitting media (PTM) can be overcome by thermal decomposition of an oxygen-rich solid PTM (NaCl + NaClO 3 ). To illustrate the technical challenges the method overcomes, we applied this new method for two known pentavalent A (I) B (V) O 3 postperovskite compounds. We successfully synthesized the two postperovskites, NaOsO 3 and NaIrO 3 , and quenched to ambient conditions. Furthermore, we report the discovery of a new low-pressure polymorph of NaIrO 3 , illustrating the high potential for new materials discovery. This new method will enable realization of new high-oxidation-state postperovskites and can be applied for many other structure families in a P , T parameter space that is not easily accessible using conventional high-pressure synthesis methods.

Solid-solid reaction, particularly in the Fe-O binary system, has been extensively studied in the past decades because of its various applications in chemistry and materials and earth sciences. The recently synthesized pyrite-FeO 2 at high pressure suggested a novel oxygen-rich stoichiometry that extends the achievable O-Fe ratio in iron oxides by 33%. Although FeO 2 was synthesized from Fe 2 O 3 and O 2 , the underlying solid reaction mechanism remains unclear. Herein, combining in situ X-ray diffraction experiments and first-principles calculations, we identified that two competing phase transitions starting from Fe 2 O 3 : (1) without O 2 , perovskite-Fe 2 O 3 transits to the post-perovskite structure above 50 GPa; (2) if free oxygen is present, O diffuses into the perovskite-type lattice of Fe 2 O 3 leading to the pyrite-type FeO 2 phase. We found the O-O bonds in FeO 2 are formed by the insertion of oxygen into the Pv lattice via the external stress and such O-O bonding is only kinetically stable under high pressure. This may provide a general mechanism of adding extra oxygen to previous known O saturated oxides to produce unconventional stoichiometries. Our results also shed light on how O is enriched in mantle minerals under pressure.

Noncentrosymmetric (NCS) mixed-metal chalcogenides have attracted significant attention lately because of their structural multiplicities, strong second-harmonic-generation (SHG) efficiencies ( d ij ) and large laser-induced damage thresholds (LIDTs), which make them promising nonlinear-optical (NLO) materials in mid- and far-IR (MFIR) applications. In this work, a ternary mixed-metal material, Cd 4 GeS 6 , has been synthesized by reacting CdS with GeS 2 via a solid-state method at 1273 K. It exhibits a unique tetrahedral-stacking NCS framework structure consisting of two types of [Cd 2 S 7 ] asymmetric groups and dispersed GeS 4 tetrahedra. Remarkably, Cd 4 GeS 6 shows type-I phase-matching ability and achieves a desired balance between strong d ij (about 1.1AgGaS 2 ) and large LIDT (about 3.6AgGaS 2 ), demonstrating that this material satisfies the essential requirements as a promising MFIR NLO candidate. Moreover, theoretical calculations were performed for a better understanding of the structure-property relationships.

The structural and vibrational properties of SrWO 4 have been studied experimentally up to 27 and 46 GPa, respectively, by angle-dispersive synchrotron X-ray diffraction and Raman spectroscopy measurements as well as using ab initio calculations. The existence of four polymorphs upon quasi-hydrostatic compression is reported. The three phase transitions were found at 11.5, 19.0, and 39.5 GPa. The ambient-pressure SrWO 4 tetragonal scheelite-type structure (S.G. I4 1 /a) undergoes a transition to a monoclinic fergusonite-type structure (S.G. I2/a) at 11.5 GPa with a 1.5% volume decrease. Subsequently, at 19.0 GPa, another structural transformation takes place. Our calculations indicate two possible post-fergusonite phases, one monoclinic and the other orthorhombic. In the diffraction experiments, we observed the theoretically predicted monoclinic LaTaO 4 -type phase coexisting with the fergusonite-type phase up to 27 GPa. The coexistence of the two phases and the large volume collapse at the transition confirm a kinetic hindrance typical of first-order phase transitions. Significant changes in Raman spectra suggest a third pressure-induced transition at 39.5 GPa. The conclusions extracted from the experiments are complemented and supported by ab initio calculations. Our data provides insight into the structural mechanism of the first transition, with the formation of two additional W-O contacts. The fergusonite-type phase can be therefore considered as a structural bridge between the scheelite structure, composed of [WO 4 ] tetrahedra, and the new higher pressure phases, which contain [WO 6 ] octahedra. All the observed phases are compatible with the high-pressure structural systematics predicted for ABO 4 compounds using crystal-chemistry arguments such as the diagram proposed by Bastide.