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• Dumbbell and sphere-like CuO are successfully synthesized by a facile method. • Their morphologies are obviously affected by the reaction temperature. • Both of them possess porous three dimensional structures. • Both of them display good rate capability and high cycling stability. Dumbbell and sphere-like CuO with porous three dimensional (3D) structures are synthesized via a simple chemical solution method and subsequent annealing treatment approach. The morphologies of the samples are obviously affected by the reaction temperature. Benefiting from the desired porous 3D structure, the dumbbell and sphere-like CuO are used as the anodes materials in LIBs, evidencing good rate capability (569 mAh g−1 for dumbbell-like CuO and 467 mAh g−1 for sphere-like CuO at 5 C) and high cycling stability (680 and 601 mAh g−1 for dumbbell-like CuO and sphere-like CuO over 400 cycles at 2 C, respectively). [ABSTRACT FROM AUTHOR]

• 2D α-Co(OH) 2 -NS was synthesized via a novel reduction-oxidation strategy. • The thickness of α-Co(OH) 2 -NS is only about 2–3 nm. • The BET surface area of the α-Co(OH) 2 -NS is 237.7 m2/g. • The OER activity is highly depended on the 2D structure. • The overpotential of α-Co(OH) 2 -NS is only 278 mV with a Tafel slope 77 mV/dec. Highly active, durable and cost-effective electrocatalysts for oxygen evolution are critical to storage processes and energy conversion between electricity and chemicals. Here, an excellent OER catalyst of 2D ultrathin α-Co(OH) 2 nanosheets was synthesized via a reduction–oxidation strategy. The 2D ultrathin α-Co(OH) 2 nanosheets could effectively catalyse the OER in alkaline media with an overpotential of only 278 mV at 10 mA/cm2 and a relatively small Tafel slope (77 mV/dec) as well as extraordinary stability, much greater than that of the α-Co(OH) 2 nanoflower and no-load Ni foam. [ABSTRACT FROM AUTHOR]

• CFO and CCFO electrodes were synthesized by pulsed laser deposition (PLD). • The composition of products can be easily tuned. • The OER activity highly depends on the Cr doping. • The overpotential of CCFO electrode is 293 mV with a Tafel slope 76 mV/dec. • CCFO electrode shows excellent durability and stability. Traditional powder OER catalysts have many disadvantages such as the extremely complicated electrode preparation process. Herein, squama-like Co 0.95 Cr 0.05 Fe 2 O 4 thin film electrode is directly deposited on flexible Ni foam substrate by a novel method of pulsed laser deposition. Cr doping leads to the electrode highly effective for OER, and the current density is about 2.1 times of that compared with undoped CoFe 2 O 4 thin film at 1.8 V. The Co 0.95 Cr 0.05 Fe 2 O 4 thin film exhibits an overpotential of 293.3 mV at 10 mA/cm2 as well as extraordinary stability, which is far better than that of CoFe 2 O 4 thin film and no-load Ni foam. [ABSTRACT FROM AUTHOR]