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 CO 2 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 CO 2 to methanol. The conversion of CO 2 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 CO 2 adsorption capacity through interactions with copper and induce the in situ formation of additional Cu + species from Cu 0 under a CO 2 atmosphere, thereby constructing bifunctional Cu 0 /N-Cu + catalytic sites. Within these sites, Cu 0 sites promote hydrogen dissociation, while Cu + sites interacting with nitrogen synergistically facilitate the CO 2 adsorption and activation. This enables the stepwise hydrogenation of the CO 2 -derived intermediates into methanol.