Chitosan–lignin carbon framework-encapsulated Cu catalyst facilitates base-free hydrogen evolution from methanol/water

Abstract

Methanol reforming in aqueous solution provides a significantly attractive and promising pathway to release hydrogen with mild H₂ release conditions and high H₂ storage capacity. Exploring non-noble metal-based catalysts with sufficiently high activity, stability, and selectivity for H₂ remains a great challenge. We report here the construction of a chitosan–lignin (CS–LN) carbon framework bio-composite-encapsulated Cu catalyst (Cu@CS–LN) with high loading and dispersion for base-free hydrogen generation from aqueous-phase methanol reforming below 210 °C. With optimized conditions, the hydrogen generation rate of Cu@CS–LN (2.5 × 10⁵ μmol_H2 g_Cu⁻¹ h⁻¹) represents an approximately 2-fold enhancement compared with Cu@CS without lignin incorporation, and more than 3–5 times higher than commercial Cu-based catalysts such as Rainie Cu or CuO/ZnO. The catalyst underwent an intensified water gas shift reaction (WGSR), and it also exhibited extraordinary selectivity toward the CO byproduct. The unique carbon framework structure of CS–LN through electrostatic densification self-assembly not only enhanced the adsorption and dispersion of Cu species, but it also stabilized and further reduced the Cu particles to active phase Cu during the hydrogen generation reaction to promote catalytic activity and stability without obvious catalyst deactivation detected after running for 150 hours. This specific hydrogen production technology exhibits great potential for hydrogen-powered polymer electrolyte membrane (PEMFCs) fuel cells.