The Al effect on the electrochemical properties of layered double hydroxides (LDHs) is not properly probed, although it is demonstrated to notably promote the capacitive behavior of LDHs. Herein, ternary NiCo 2 Al x layered double hydroxides with varying levels of Al stoichiometry are purposely developed, grown directly on mechanically flexible and electrically conducting carbon cloth (CC@NiCo 2 Al x -LDH). Al plays a significant role in determining the structure, morphology, and electrochemical behavior of NiCo 2 Al x -LDHs. At an increasing level of Al in NiCo 2 Al x -LDHs, there is a steady evolution from 1D nanowire to 2D nanosheets. The CC@NiCo 2 Al-LDH at an appropriate level of Al and with the nanowire-nanosheet mixed morphology exhibits both significantly enhanced electrochemical performance and excellent structural stability, with about a 2.3-fold capacitance of NiCo 2 -OH. When applied as the anode in a flexible asymmetric supercapacitor (ASC), the CC@NiCo 2 Al-LDH gives rise to a remarkable energy density of 44 Wh kg −1 at the power density of 462 W kg −1 , together with remarkable cyclic stability with 91.2% capacitance retention over 15 000 charge-discharge cycles. The present study demonstrates a new pathway to significantly improve the electrochemical performance and stability of transition metal LDHs, which are otherwise unstable in structure and poorly performing in both rate and cycling capability.

Carbon-supported low-Pt ordered intermetallic nanoparticulate catalysts (PtM 3 , M = Fe, Co, and Ni) are explored in order to enhance the oxygen reduction reaction (ORR) activity while achieving a high stability compared to previously reported Pt-richer ordered intermetallics (Pt 3 M and PtM) and low-Pt disordered alloy catalysts. Upon high-temperature thermal annealing, ordered PtCo 3 intermetallic nanoparticles are successfully prepared with minimum particle sintering. In contrast, the PtFe 3 catalyst, despite the formation of ordered structure, suffers from obvious particle sintering and detrimental metal-support interaction, while the PtNi 3 catalyst shows no structural ordering transition at all but significant particle sintering. The ordered PtCo 3 catalyst exhibits durably thin Pt shells with a uniform thickness below 0.6 nm (corresponding to 2-3 Pt atomic layers) and a high Co content inside the nanoparticles after 10 000 potential cycling, leading to a durably compressive Pt surface and thereby both high activity (fivefold vs a commercial Pt catalyst and 1.7-fold vs an ordered PtCo intermetallic catalyst) and high durability (5 mV loss in half-wave potential and 9% drop in mass activity). These results provide a new strategy toward highly active and durable ORR electrocatalysts by rational development of low-Pt ordered intermetallics.

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Highly active and stable electrocatalysts based on non-precious metals for hydrogen evolution reaction (HER) in alkaline solution are urgently required for enabling mass production of clean hydrogen in industry. Herein, core–shell NiOOH/Ni nanoarchitectures supported on the conductive carbon cloth have been successfully prepared by a facile electrodeposition process of Ni, and a subsequent in situ electrochemical oxidation. When explored as an alkaline HER electrocatalyst, the as-synthesized NiOOH/Ni nanoarchitecture requires only a low overpotential of ∼111 mV to attain a current density of −10 mA cm−2, demonstrating its strong catalytic capability of hydrogeneration. The excellent HER activity could well be attributed to the decreasing charge transfer resistance and competitive electrochemical active area of the amorphous NiOOH, compared with inactive Ni substrate. The feasible methodology established in this study can be easily expanded to obtain a series of nano-sized metal oxyhydroxide materials for various energy conversion and storage applications, where Ni-based nanomaterials are among the highly active ones.

Novel 3D flower-like bismuth oxyiodide (BiOI) nanomaterials were obtained via a facile solvothermal method using bismuth nitrate (Bi(NO3)3) and potassium iodide (KI) as precursors and diethylene glycol as the capping reagent. The morphology of the BiOI nanoarchitecture strongly depends on the experimental conditions such as the presence of diethylene glycol and hydrothermal time. The photocatalytic property of the BiOI nanostructures by monitoring the degradation of rhodamine B (RhB) and methyl orange (MO) mixed dyes was studied under visible light illumination, which has not been reported previously. The degradation of single cationic RhB dye is faster when compared with that of anionic MO dye. This result is due to the surface negative charges on the BiOI nanoflowers that display good selectivity towards positive RhB dye organic groups owing to electrostatic attraction.

3D BiOCl hierarchical nanostructures assembled with nanosheets have been successfully synthesized via a facile solvothermal route with Bi(NO3)3, KCl, poly(vinylpyrrolidone) (PVP), and diethylene glycol (DEG). Photocatalytic experiment illustrated that the as-synthesized BiOCl nanoflowers exhibited superior photocatalytic activity than that of BiOCl microrods and Degussa P25 in the degradation of single and mixed dye solutions under UV irradiation, which has not been reported previously. Besides, the stability of the product in mixed organic dye photodegradation process was also investigated for the first time.