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.

Direct charge transfer at wet-processed organic/organic heterojunction interfaces is observed using femtosecond interfacial sensitive spectroscopy. UV–vis absorption and ultraviolet photoelectron spectroscopy both indicate that a new interfacial energy gap (∼1.2 eV) exists when an interface is formed between regioregular poly(3-hexylthiophene-2,5-diyl) and poly(benzimidazobenzophenanthroline). Resonant pumping at 1.2 eV creates an electric field-induced second-order optical signal, suggesting the existence of a transient electric field due to separated electrons and holes at interfaces, which recombine through a nongeminate process. The fact that direct charge transfer exists at wet-processed organic/organic heterojunctions provides a physical foundation for the previously reported ground-state charge transfer phenomenon. Also, it creates new opportunities to better control charge transfer with preserved momentum and spins at organic material interfaces for spintronic applications.

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.

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