In Situ Formed Bimetallic Carbide Ni6Mo6C Nanodots and NiMoOx Nanosheet Array Hybrids Anchored on Carbon Cloth: Efficient and Flexible Self-Supported Catalysts for Hydrogen Evolution

Water electrolysis is a promising technique to produce high-quality hydrogen. However, the design and synthesis of high-performance nonprecious metal catalysts for the hydrogen evolution reaction are still confronted with challenges because of their high overpotential and poor flexibility. We herein reported in situ formed bimetallic carbide Ni6Mo6C nanodot and NiMoOx nanosheet array hybrid electrocatalyst supported on activated carbon cloth (Ni6Mo6C/NiMoOx/ACC), which is manufactured by controlling the diffusion of carbon atoms into precursor NiMoO4 nanosheets from activated carbon cloth to produce active species bimetallic carbide during annealing in a H-2 atmosphere. The unique hierarchical structure of NiMoOx nanosheet arrays grown on ACC could significantly promote both mass transport and electric conductivity, and the embedded Ni6Mo6C with moderated hydrogen adsorption ability (Delta GH* = -0.13 eV) and low water dissociation barrier (Delta Gb = 0.27 eV) exhibited remarkable performance and durability for the hydrogen evolution reaction (HER). Optimal Ni6Mo6C/NiMoOx/ACC demonstrates zero onset overpotential and an overpotential of only 29 mV at a current density of 10 mA cm(-2) with long-term stability (60 h loss-free continuous operation) in 1.0 M KOH solution, even surpassing the benchmark Pt/C catalyst. Especially, the as-made electrocatalyst shows robust flexibility and its high electrocatalytic performance almost keeps constant under distorted states, thus meeting the requirements of flexible electrocatalysts such as bendability. These findings afford a new idea to integrally construct highly efficient flexible electrocatalysts.