ZnxCo3‐xO4 nanoarrays are grown hydrothermally on Ti foils using appropriate ratios of Zn(NO3)2 and Co(NO3)2, NH4F and Co(NH2)2 in H2O together with the Ti substrate (autoclave, 120 °C, 10 h).

A pine‐shaped Pt nanostructured electrode with under‐water superaerophobicity for ultrahigh and steady hydrogen evolution reaction (HER) performance is successfully fabricated by a facile and easily scalable electrodeposition technique. Due to the lower bubble adhesive force (11.5 ± 1.2 μN), the higher bubble contact angle (161.3° ± 3.4°) in aqueous solution, and the smaller size of bubbles release for pine‐shaped Pt nanostructured electrode, the incomparable under‐water superaerophobicity for final repellence of bubbles from submerged surface with ease, is successfully achieved, compared to that for nanosphere electrode and for Pt flat electrode. With the merits of superior under‐water superaerophobicity and excellent nanoarray morphology, pine‐shaped Pt nanostructured electrode with the ultrahigh electrocatalytic HER performance, excellent durability, no obvious current fluctuation, and dramatically fast current density increase at overpotential range (3.85 mA mV−1, 2.55 and 13.75 times higher than that for nanosphere electrode and for Pt flat electrode, respectively), is obtained, much superior to Pt nanosphere and flat electrodes. The successful introduction of under‐water superaerophobicity to in‐time repel as‐formed H2 bubbles may open up a new pathway for designing more efficient electrocatalysts with potentially practical utilization in the near future.

show superb activities than either of the parent metal catalyst, and comparable to the best noble catalysts (e.g., IrO 2 and RuO 2 ) [ 12 ] for oxygen evolution reaction (OER), which is a key component for a number of energy storage and conversion processes. [ 13 ] However, the lack of investigations on the oxygen reduction reaction (ORR) activities of LDHs greatly limits their further application in rechargeable metal-air battery and unitized regenerative fuel cell. Thus it is intriguing to evaluate the bifunctional performance of LDH-based materials in order to broadening the usages in electrochemistry.The specifi c activity of the material for the target reaction is usually highly dependent on the chemical composition and their electronic structures. [ 14,15 ] For OER, it is found that a small amount of Fe doping was effective for enhancing the OER activities of Ni hydroxides or oxides, possibly due to the enhanced structure disorder and conductivity. [ 16 ] Recently, an excellent OER performance was observed on amorphous NiCoFe oxides which were prepared by a photochemical route. [ 17 ] As to the ORR, Co and Fe ions are believed to be the active center with specifi c crystal and electronic structures. [ 18,19 ] Moreover, Co-based compounds have been widely studied recently as bifunctional materials for oxygen electrocatalysis. [ 20 ] LDHs, which offer a wide tunability of diverse metal species and ratios in the intralayer as well as a large interlayer spacing which may accelerate the ion diffusion, should be of great potential with high bifunctional performance.In this work, the ORR and OER activities of trinary NiCoFe-LDHs have been systematically investigated. It is observed that the NiCoFe-LDH showed a reasonable bifunctional performance while the sample after preoxidation treatment (denoted as O-NiCoFe-LDH) would lead to a signifi cant enhancement. This improvement was attributed to the formation of Co 3+ in the intralayer, result in the conductivity improvement of the material. To demonstrate the practical application of the LDH catalyst, the O-NiCoFe-LDH loaded on Tefl on-treated carbon fi ber paper (T-CFP) only required a potential hysteresis of ≈800 mV to achieve stable current densities of ≈20 mA cm −2 for ORR and OER for matching the current requirement of rechargeable zinc-air batteries, [ 21 ] much smaller than those of the commercial 60 wt% Pt/C and 20 wt% Ir/C catalysts. This fi rst investigation on the bifunctional performance of LDHs not Layered double hydroxides (LDHs) are a family of high-profi le layer materials with tunable metal species and interlayer spacing, and herein the LDHs are fi rst investigated as bifunctional electrocatalysts. It is found that trinary LDH containing nickel, cobalt, and iron (NiCoFe-LDH) shows a reasonable bifunctional performance, while exploiting a preoxidation treatment can signifi cantly enhance both oxygen reduction reaction and oxygen evolution reaction activity. This phenomenon is attributed to the partial conversion of Co 2+ to Co 3+ state in the pr...

Direct liquid-feed fuel cells possess high energy and power densities, but suffer from severe adhesion of gas products. Here, a "superaerophobic" surface that enables a small release size and fast evolution behavior of the gas product is introduced, thereby, maximizing and stabilizing the working area. Consequently, the "superaerophobic" nanostructured Cu electrodes exhibit excellent performance as anodes in a direct hydrazine fuel cell.

Amorphous Co-doped MoS2 nanosheet coated metallic CoS2 nanocubes with ultrahigh HER activity were prepared via one-pot hydrothermal synthesis.

A metallic CoS2 nanopyramid array on 3D carbon fiber paper with ultrahigh HER activity was prepared via solvothermal synthesis.

As a new type of capacitor–battery hybrid energy storage device, metal‐ion capacitors have attracted widespread attention because of their high‐power density while ensuring energy density and long lifespan. Potassium‐ion capacitors (KICs) featuring the merits of abundant potassium resources, lower standard electrode potential, and low cost have been considered as potential alternatives to lithium‐/sodium‐ion capacitors. However, KICs still face issues including unsatisfactory reaction kinetics, low energy density, and poor lifetime owing to the large radius of the potassium ion. In this Review, the importance of emerging potassium‐ion capacitor is addressed. The Review offers a brief discussion of the fundamental working principle of KICs, along with an overview of recent advances and achievements of a variety of electrode materials for dual carbon and non‐dual carbon KICs. Furthermore, electrolyte chemistry, binders as well as electrode/electrolyte interface, are summarized. Finally, existing challenges and perspectives on further development of KICs are also presented.

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