CsCu 2 I 3 mixed with Cs 3 Cu 2 I 5 has shown potential applications as white-light-emitting materials, while their growth, structural evolution behaviors, and their impact on photoluminescence of CsCu 2 I 3 nanocrystals (NCs) are still not known. In this work, we investigated the growth and structural evolution of CsCu 2 I 3 nanocrystals with increasing reaction temperature. At low temperature and in the presence of a high dosage of oleic acid and oleylamine, Cs 3 Cu 2 I 5 nanoparticles, rather than CsCu 2 I 3 NCs, preferred to form in the hot-injection reaction system. Increasing the reaction temperature promoted the formation of CsCu 2 I 3 nanorods. Phase-pure CsCu 2 I 3 nanorods were steadily obtained at 180 °C. Structural evolution from less copper-containing NCs to copper-rich ones in the low-temperature reaction condition is highly related to the coordination of copper ions with OAm. More importantly, accompanying the growth of nanorods and structural evolution from Cu 3 Cs 2 I 5 to CsCu 2 I 3 , the color of photoluminescence emission of NCs changed from blue to nearly white and to yellow, but their photoluminescence quantum yield decreased from 36.00 to 9.86%. The finding in this work would give a view to the structural evolution of copper-containing perovskite-like halides, being helpful for adjusting their photoluminescence in white LEDs.

Bimetallic oxides ABO x (x = 2, 3, and 4) with multiple lattice sites have shown numerous properties, blossoming into diverse applications, while regulating the valence state at the A or B site usually causes a dramatic change in the crystal structure, giving rise to uncertainties in comprehending the structure–property relationships. Herein, we synthesized bimetallic layered crednerite CuMnO2 with double-coordinate Cu cations at the A site and hexa-coordinate Mn cations at the B site via a cetyltrimethylammonium bromide (CTAB) modified hydrothermal method. By controlling the crystal growth temperature, valence states tailoring was implemented along with the stabilization of the monoclinic layered structure. The regulation process was followed by morphology changes of the CuMnO2 crystal in a sequence: triangular sheets (140 °C), nanowires (160 °C), hexagonal prisms (180 °C), and octahedrons (over 200 °C). Interestingly, the oxidation states of Cu2+ and Mn2+ were found for triangular sheets, which transformed to the mixed valency Cu+/Cu2+ and Mn3+/Mn2+ for nanowires, and then to the dominant Cu+ and Mn3+ oxidation states for hexagonal prisms and octahedrons. Among all morphologies, nanowires showed a higher aspect ratio, preferentially growing along the (002) plane, which when first applied to a supercapacitor, exhibited the highest specific capacitance of 921 F/g at the current density of 1 A/g. The synergistic effect between the special redox equilibrium and controlled one-dimensional crystal architecture is uncovered to optimize the electrochemical energy storage. The methodology reported in this work creates a new path of functional bimetallic oxides ABO x with tailored valence states, controllable crystal growth, and stable crystal structure for optimum energy storage applications.

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Electrochemical cation de/intercalation has long been investigated for energy-relevant applications, while anion de/intercalation is comparatively highly challenging, although promising for promoting the performance of materials. Herein, layered nickel hydroxychloride was selected as a model multianion-containing inorganic functional material to study. Hierarchical flower-like microspheres self-assembled from nanosheets were synthesized via a solvothermal method. The as-prepared nickel hydroxychloride was built up from neutral layers of [Ni(OH) 3/3 Cl 3/3 ] octahedra, showing an expanded interlayer spacing of 0.57 nm. With this unique microstructure, Cl − deintercalation and OH − intercalation were accomplished through an effective nonelectrochemical process. The nickel hydroxychloride Ni(OH) 0.99 Cl 1.01 with a maximum Cl − ion content was found to possess the largest interlayer spacing, which when first employed as electrode materials for supercapacitor, delivered an ultrahigh specific capacitance of 3831 F/g at a current density of 1 A/g. For the latter case, Ni(OH) 2.18 (H 3 O) 0.18 with a maximum OH − content showed a specific capacitance of 1489 F/g at 1 A/g. Expanded interlayer spacing associated with the anion de/intercalation is the key that enhances ion diffusion kinetics between layers. The methodology of anion de/intercalation reported in this work would provide hints of exploring novel multianion-containing materials with anion de/intercalation necessary for high-performance energy applications.

The synergistic double interfaces in CC@Ni(OH)Cl@NiO flexible electrode stabilize Ni–O covalency and stimulate active electronic behavior for superior electrochemical performance.