LAUSR

DOI: 10.1002/aenm.201800575 reaction (HER) has been identified as a promising technology for hydrogen production.[3] Generally, platinum is normally working as HER electrocatalyst for its high catalytic activity and stability at various pH values (0–14).[4,5] Unfortunately, the largescaled industrial utilization with Pt catalyst is hindered by its high cost and scarcity of reserves. Hence seeking highly effective, low-cost, and pH-universal durable alternates becomes an important topic. In 1973, Levy and Boudart first reported the “platinum-like behavior” of transition metal carbides (TMCs).[6] It is worth mentioning that this pioneering work indicated carbon could modify the surface electron properties of tungsten atoms in such a manner that makes them more platinum-like. In particular, sp-electron of carbon increases electron-to-atom ratio, generating relatively more Pt-like electronic structure. Since then, many works have been focused on the electronic and structural properties of groups IVB–VIB transition metals and their catalytic properties.[7–9] Specially, tungsten carbide and molybdenum carbide are two of the most studied TMCs for the HER. Due to their platinum-like properties, they are often adopted as support to reduce the mass-loading of Pt or a stand-alone catalysts for HER. However, the catalytic activities of these TMCs are relatively lower compared to those of Pt, and the system still cannot avoid the usages of costly Pt when TMCs serve as support. Brian M. Leonard synthesized carbides of nine transition metals in group IV–VI and compared their catalytic activities toward HER. Specially, they concluded that Mo2C, WC, and V8C7 deliver particularly enhanced HER activity compared with others.[10] In 2011, Shen and co-workers first took advantage of the platinum-like feature of V8C7 to reduce the usage of Pt. Owing to the synergistic effect between V8C7 and Pt, the resulting sample possessed remarkable activity toward oxygen reduction reaction (ORR).[11] Hereafter, Chu and co-workers fabricated hierarchical structures comprising VC nanoparticles encapsulated in graphitic carbon network via magnesium thermic reaction, and the VC composite showed moderate HER performance in acidic medium.[12] However, owing to the high synthetic temperature of vanadium carbide, they usually deliver irregular morphology, low specific surface area, and Exploring low-cost hydrogen evolution reaction (HER) catalysts with remarkable activity over wide pH range (0–14) still remains an enormous challenge. Herein, for the first time, a novel platinum-like, double-deck carbon coated V8C7 networks with the highly active (110) facet exposed as a new efficient HER electrocatalyst is reported. The single-crystal interweaved V8C7 networks are designed and fabricated based on a low crystal-mismatch strategy and confinement effect of double-deck carbon coating. In addition, electrochemical tests and theoretical simulation indicate that the metallic character of V8C7, high-activity of exposed facet, and low barrier energy for water dissociation can contribute to highly catalytic activity of HER. Impressively, the HER performances of the interweaved V8C7 networks can be comparable to those of Pt at an all-pH environment, with Tafel slopes of 44, 64, and 34.5 mV dec−1and overpotential of 47, 77, and 38 mV at −10 mA cm−2 in 1 m KOH, 0.1 m phosphate buffer, and 0.5 m H2SO4, respectively. This work provides a blueprint for exploring new-type platinum-like catalysts for various energy conversion systems.