Dual-Function Orchestration of N-Doped Cu Nanocatalysts for CO ₂ Hydrogenation to Methanol

Copper-based catalysts remain among the most extensively studied systems for the hydrogenation of CO2 to methanol owing to their high catalytic performance. However, advancements in the development of copper-based catalysts rely heavily on the incorporation of metal additives and the utilization of catalyst supports. In this study, an unsupported, nonmetallic N-doped Cu nanocatalyst was prepared by an ammonia complexation precipitation method, which has favorable catalytic performance in the hydrogenation of CO2 to methanol. The conversion of CO2 and selectivity of methanol reach up to 6.9 and 71.7% (240 °C, 3.0 MPa), respectively. Based on combined structural and electronic property analyses with density functional theory calculations, N species doped at copper interstitial sites exhibit enhanced CO2 adsorption capacity through interactions with copper and induce the in situ formation of additional Cu+ species from Cu0 under a CO2 atmosphere, thereby constructing bifunctional Cu0/N-Cu+ catalytic sites. Within these sites, Cu0 sites promote hydrogen dissociation, while Cu+ sites interacting with nitrogen synergistically facilitate the CO2 adsorption and activation. This enables the stepwise hydrogenation of the CO2-derived intermediates into methanol.