Interface Engineering of Network-Like 1D/2D (NHCNT/Ni─MOF) Hybrid Nanoarchitecture for Electrocatalytic Water Splitting.

Abstract

Here, integrated functional components into a hybrid heterostructure via highly stabilized network-like interconnected electronic nanoarchitecture of 1D N-doped holey-carbon nanotube (NHCNT) with 2D nickel─metal-organic framework (Ni─MOF) nanosheets are developed as high-performance electrocatalyst for overall water splitting. The NHCNT promoting electron transport pathways in electrocatalyst, and formation of holes in nanotubes further enables excellent diffusion of ions for promoting the overall reaction rate. An excellent combination of 1D/2D structure of NHCNT/Ni─MOF-4 electrocatalyst exhibits excellent oxygen evolution reaction (η₁₀ = 207.8 mV, and Tafel = 62.6 mV dec^-1) and reasonable hydrogen evolution reaction (η₁₀ = 159.8 mV, and Tafel = 107.69 mV dec^-1) activity with consistent and stable performance in a 1 m KOH. The highly interconnected network structure contains Ni²⁺ and Ni³⁺ species in the NHCNT/Ni─MOF-4 electrocatalyst, which possesses high specific surface area (SSA) (235.53 m² g^-1), electrochemically active surface area (ECSA) (796.2 cm²), mass activity (4.76 mA mg^-1), and turnover frequency (3.99 × 10^-2 s^-1), which provide remarkable electrocatalytic performance via generating synergy between the NHCNT and Ni─MOF. For overall water splitting, NHCNT/Ni─MOF-4 attains a low cell voltage (1.77 V@10 mA cm^-2).