Heteronuclear Dual Single-Atom Catalysts for Ambient Conversion of CO2 from Air to Formate

Single-atom catalysts (SACs) can achieve the maximum metal atom utilization, which exhibit great potential for the chemical transformation of CO2. However, an isolated single active site is less satisfactory for catalyzing multiple molecule reactions involving CO2 hydrogenation. In this work, we propose heteronuclear dual SACs composed of Pd and 3d transition metals supported by covalent triazine frameworks (CTFs). Among these catalysts, the optimized Pd1-Co1/CTF catalyst exhibits up to 84.6% conversion of the captured CO2 from air into formate at 30 degrees C and 1 bar. The in situ DRIFT characterization and density functional theory calculations reveal that CO2 in air is captured by the Et3N solution as bicarbonate, which is then hydrogenated into formate via the Pd1-Co1 heteronuclear dual single atom with an energy barrier as low as 17.2 kcal/mol. The heteronuclear Pd and Co metal atoms act as the active site for H2 activation and CO2 adsorption, respectively, thus exhibiting enhanced activity for formate synthesis with a synergistic effect. These findings present an insight into the synthesis and application of heteronuclear dual SACs and pave an avenue for conversion of CO2 in the air by heterogeneous catalysts.