Methane pyrolysis (MP) offers a promising pathway for CO₂-free hydrogen production while simultaneously generating high-value carbon materials. However, current catalysts face challenges such as high melting points, limited catalytic efficiency, poor stability, and insufficient utilization of the carbon by-products. Here, we report a new family of quaternary liquid alloy catalysts (LACs) developed by incorporating a fourth element (Mn, Fe, Co, Cu, Mg, Al, or Cr) into the NiMo-Bi system. Among them, the NiMoMn-Bi alloy demonstrated the most outstanding performance, with a remarkably low activation energy of 72.4 kJ mol⁻¹, enabling efficient MP over a broad temperature range of 350–1050 °C. This catalyst achieved a fourfold increase in hydrogen production efficiency compared with its ternary counterpart. Furthermore, NiMoMn-Bi exhibited 99.98% H₂ selectivity and outstanding stability over 260 h of continuous operation. Notably, the carbon nanotubes synthesized from NiMoMn-Bi and NiMoCu-Bi alloys exhibited excellent Li⁺ battery performance, highlighting their potential for energy storage applications.
 

Methane pyrolysis, molten alloy catalysts, density functional theory, reaction kinetic