Engineering a Hydrothermally Stable Ni@NC Catalyst for Efficient Hydrogen Production from Aqueous-Phase Reforming of Biomass Wastewater

Biomass utilization produces large amounts of wastewater contaminated with phenolic and organic compounds, posing a major challenge for purification and resource recovery. To address this, the development of highly active, hydrothermally stable non-noble-metal catalysts is essential for applying aqueous-phase reforming (APR) to valorize this waste stream and produce sustainable hydrogen. In this work, a carbon-encapsulated nickel catalyst with a high metal loading (36.7 wt %), excellent dispersion, and small nickel particle size (∼5 nm) was prepared via pyrolysis. The coordination between amino functional groups in chitosan and nickel ions facilitated the homogeneous dispersion of the chitosan-nickel precursor. Pyrolysis resulted in the nickel nanoparticles being embedded well within a nitrogen-doped carbon (NC) matrix, which effectively inhibited particle agglomeration and improved hydrothermal stability. Catalytic performance tests revealed that the Ni@NC-350 catalyst achieved a phenol conversion of over 90% and a hydrogen selectivity of nearly 85%. Notably, after six consecutive APR cycles, no significant aggregation or deactivation of nickel nanoparticles was observed, indicating excellent hydrothermal stability. This study thus provides a robust and highly stable Ni-based catalyst, demonstrating promising application potential in the efficient treatment of phenol-containing organic wastewater with simultaneous hydrogen production.