Chemical looping performance can be improved through the controllable exsolution of the redox phase in a spinel solution.

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The successful designing of low‐cost and highly active electrocatalytic materials from earth‐abundant elements are favorable for the large scale production of hydrogen from water splitting. Herein, the controllable sandwiching of reduced graphene oxide (RGO) in hierarchical defect‐rich MoS2 ultrathin nanosheets (MoSGMoS) with vertical alignment and expanded interlayer spacing is synthesized by hydrothermal method. The MoSGMoS product exhibits outstanding electrocatalytic activity for hydrogen evolution reaction (HER) with an onset overpotential of 24.3 mV, low overpotentials of 72 mV at 10 mA cm−2 and 384 mV at 1300 mA cm−2, a small Tafel slope of 44.7 mV decade−1, large exchange current density of 0.67 mA cm−2, and high durability in H2SO4 solution. The HER performance of the MoSGMoS catalyst is much better than most of the reported MoS2‐based catalysts, especially in terms of onset overpotential and cathodic current density. The synergistic effect between defect‐rich MoS2 ultrathin nanosheets with hierarchical structure, vertical alignment and expanded interlayer spacing, and conductive RGO is responsible for the outstanding HER activity. This method may open a new way to grow hierarchical MoS2 nanosheets on carbonaceous materials for enhanced hydrogen production from water splitting.

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The fabrication of non-precious-metal and highly active electrocatalytic materials to drive oxygen evolution reaction (OER) at low overpotential from earth-abundant elements by a low-cost and easy method is extremely important for many advanced energy technologies. Herein, a non-noble-metal catalyst with FeNi@nitrogen-doped graphene dispersed on a nitrogen-doped carbon matrix (named FeNi@NGE/NC) is synthesized by a facile one-pot pyrolysis process. In this composite, FeNi alloy nanoparticles encapsulated with few-layer nitrogen-doped graphene are uniformly anchored on a nitrogen-doped carbon matrix. The FeNi@NGE/NC composite exhibits outstanding electrocatalytic performance for OER with a low overpotential of 275 mV at 10 mA cm–2, a small Tafel slope of 41.2 mV dec–1, and high stability in 1 M KOH solution. Even at the low concentration of basic solution (0.1 M KOH), it still displays good activity for OER with an overpotential of 372 mV at 10 mA cm–2. The outstanding OER performance of the FeNi@NGE/NC composite can be mainly attributed to the fast electron transfer from the FeNi alloy to nitrogen-doped graphene shells and the high structural stability due to the protection of graphene shells and the carbon matrix. This work may open a facile and low-cost way for large-scale synthesis of non-noble metals/nitrogen-doped carbon composite electrocatalysts for practical application.