Methane decomposition to high-quality carbon nanotubes: well-distributed NiCo alloy catalysts derived from layered double hydroxide

Methane decomposition is an efficient pathway to obtain high-purity hydrogen and valuable carbon fibers, nanotubes, etc. In this work, a series of NiCo alloy catalysts with different Ni/Co ratios are successfully prepared using NiCoAl ternary layered double hydroxide (LDH) as precursors. By comparison with dual-LDH-derived catalysts and alumina-based catalysts, we found that the reduced catalysts from LDH have the characteristics of uniform particle size and distribution, and in subsequent the methane decomposition reaction over NiCo alloy catalysts show high catalytic activity and selectivity for carbon nanotubes. Furthermore, density functional theory (DFT) method is carried out to elucidate the catalytic decomposition mechanism of methane into hydrogen and carbon over a series of Ni_nCo_4−n (n = 0–4). These combined experimental and theoretical studies show that the introduction of Co element benefits the process of C–H dissociation. These combined experimental studies and DFT calculations can provide insights into the development of methane decomposition and other Ni-catalyzed methane reactions.