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The design of efficient, stable and cost-effective electrocatalysts for the hydrogen evolution reaction holds substantial significance in water electrolysis, but it remains challenging. Tremella-like nickel-molybdenum bimetal phosphide encapsulated cobalt phosphide (NiMoP/CoP) with hierarchical architectures has been effectively synthesized on nickel foam (NF) via a straightforward hydrothermal followed by low-temperature phosphating method. Based on the unique structural benefits, it significantly increases the number of redox active centers, enhances the electrical conductivity of materials, and diminishes the ion diffusion path lengths, thereby promoting efficient electrolyte penetration and reducing the inherent resistance. The as-obtained NiMoP/CoP/NF electrocatalyst exhibited remarkable catalytic activity with an ultralow overpotential of 38 mV (10 mA cm−2) and low Tafel slope of 83 mV dec−1. The straightforward synthesis process and exceptional electrocatalytic properties of NiMoP/CoP/NF demonstrate great potential for the HER to replace the precious metal catalyst. [ABSTRACT FROM AUTHOR]

Deployable structures based on origami are widely used in the application of actuators. In this paper, we present a novel family of origami-based deployable structures with constant curvature. Two categories of non-flat-foldable and non-developable degree-4 vertices (NFND degree-4 vertices) are introduced. Pyramid structures are constructed based on the NFND degree-4 vertices. Doubly symmetric and singly symmetric spherical origami tubular cells (SOTCs) are established based on pyramid structures. To construct deployable origami modules using SOTCs, linking units are introduced. The mobility of the SOTCs and origami modules is analyzed using constraint screws. To realize the construction and simulation of deployable structures, kinematic and geometric analyses of the doubly symmetric and singly symmetric SOTCs are performed. Finally, we introduce four cases for deployable structures in spherical actuators based on the combination of multiple origami modules. These case studies demonstrate the potential of these deployable origami structures in the design of spherical actuators. [ABSTRACT FROM AUTHOR]

The preparation of an electrocatalyst for the oxygen evolution reaction (OER) with high catalytic activity, good long-term durability and rapid reaction kinetics through interface engineering is of great significance. Herein, we have developed a bimetallic sulfide particle cluster-supported three-dimensional graphene aerogel (FeNiS@GA), which serves as an efficient electrocatalyst for OER, by a one-step hydrothermal method. Profiting from the synergy of the FeNiS particle cluster with high capacitance and GA with its three-dimensional porous nanostructure, FeNiS@GA shows a high specific surface area, large pore volume, low contact resistance, and decreases the electron and ion transport routes. FeNiS@GA exhibits outstanding OER activity (when the current density is 50 mA cm−2, the overpotential is 341 mV), low Tafel slope (63.87 mV dec−1) and remarkable stability in alkaline solutions, outperforming FeNiS, NiS@GA, FeS@GA and RuO2. Due to its simple synthesis process and excellent electrocatalytic performance, FeNiS@GA shows great potential to replace noble metal-based catalysts in practical applications. [ABSTRACT FROM AUTHOR]

Efficient non-noble metal bifunctional electrocatalysts can increase the conversion rate of electric energy in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, a ball & sheet MoS2/Ni3S2 composite with wide-layer-spacing and high 1T-rich MoS2 is assembled on nickel foam (NF) via a two-step solvothermal method with polymeric sulfur (S-r-DIB) as the sulfur source. The obtained material serves as both the cathode and the anode toward overall water splitting in an alkaline electrolyte. The results proved that the interpenetration of MoS2/Ni3S2-p with a ball and sheet structure increased the material active surface area and exposed more catalytic active sites, which contributed to the penetration of solution and the transfer of charge/hydrion. Meanwhile, two different semiconductors of MoS2 and Ni3S2 along with the presence of ample active sulfur edge sites and few-layer, wide-layer-spacing structures of MoS2 lead to an outstanding electrocatalytic activity. In particular, the electrodes of MoS2/Ni3S2-p only need a battery voltage of 1.55 V at 10 mA cm−2. The bifunctional electrocatalyst MoS2/Ni3S2-p also shows excellent stability at large current densities during the electrochemical test. [ABSTRACT FROM AUTHOR]