Fabricating active materials into specific macrostructures is critical in the pursuit of high electro-catalytic activity. Herein we demonstrate that a three-dimensional (3D) architecture of NiFe layered double hydroxide (NiFe-LDH) significantly reduced the onset potential, yielded high current density at small overpotentials, and showed outstanding stability in electrochemical oxygen evolution reaction.

The adhesion of as-formed gas bubbles on the electrode surface usually impedes mass-transfer kinetics and subsequently decreases electrolysis efficiency. Here it is demonstrated that nanostructured MoS₂ films on conductive substrates show a faster hydrogen evolution reaction (HER), current increase, and a more-stable working state than their flat counterpart by significantly alleviating the adhesion of as-formed gas bubbles on the electrode. This study clearly reveals the importance of a nano-porous structure for HER, which should be general and beneficial for constructing other gas-evolution electrodes.

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).

Ternary NiCoFe‐layered double hydroxide (NiCoIIIFe‐LDH) with Co3+ is grafted on nitrogen‐doped graphene oxide (N‐GO) by an in situ growth route. The array‐like colloid composite of NiCoIIIFe‐LDH/N‐GO is used as a bifunctional catalyst for both oxygen evolution/reduction reactions (OER/ORR). The NiCoIIIFe‐LDH/N‐GO array has a 3D open structure with less stacking of LDHs and an enlarged specific surface area. The hierarchical structure design and novel material chemistry endow high activity propelling O2 redox. By exposing more amounts of Ni and Fe active sites, the NiCoIIIFe‐LDH/N‐GO illustrates a relatively low onset potential (1.41 V vs reversible hydrogen electrode) in 0.1 mol L−1 KOH solution under the OER process. Furthermore, by introducing high valence Co3+, the onset potential of this material in ORR is 0.88 V. The overvoltage difference is 0.769 V between OER and ORR. The key factors for the excellent bifunctional catalytic performance are believed to be the Co with a high valence, the N‐doping of graphene materials, and the highly exposed Ni and Fe active sites in the array‐like colloid composite. This work further demonstrates the possibility to exploit the application potential of LDHs as OER and ORR bifunctional electrochemical catalysts.