Pyramidal Ni nanoparticles with highly coordinated surfaces enabled by metal–support interaction regulation for efficient H2 production from NH3

Abstract

Catalytic ammonia decomposition represents a highly efficient and environmentally friendly route for hydrogen production. Ni-based catalysts, renowned for their cost-effectiveness, have emerged as promising alternatives to noble metal catalysts. However, the influence of Ni nanoparticle morphology on catalytic performance remains underexplored. In this study, we report the construction of pyramidal Ni nanoparticles supported on CeO₂–Al₂O₃ by tuning metal–support interactions. This innovative approach significantly enhances catalytic efficiency, achieving 75.62% NH₃ conversion at 500 °C under a weight hour space velocity of 30 000 mL g_(cat)⁻¹ h⁻¹, while maintaining excellent stability over 1000 h of continuous operation. Comprehensive characterization combined with DFT calculations reveals that pyramidal Ni nanoparticles exhibit a higher proportion of highly coordinated surface sites than their spherical counterparts. The d-band center was lowered by the combined geometric and electronic effects, which weakens the Ni–N bond and facilitates N–N recombination, thereby accelerating the reaction rate. This research highlights the critical role of active metal morphology in governing catalytic behavior, offering valuable insights for the rational design of high-performance catalysts for ammonia decomposition.