Bismuth Single Atoms Resulting from Transformation of Metal-Organic Frameworks and Their Use as Electrocatalysts for CO Reduction.

The electrocatalytic reduction reaction of CO (CORR) is a promising strategy to promote the global carbon balance and combat global climate change. Herein, exclusive Bi-N sites on porous carbon networks can be achieved through thermal decomposition of a bismuth-based metal-organic framework (Bi-MOF) and dicyandiamide (DCD) for CORR. Interestingly, in situ environmental transmission electron microscopy (ETEM) analysis not only directly shows the reduction from Bi-MOF into Bi nanoparticles (NPs) but also exhibits subsequent atomization of Bi NPs assisted by the NH released from the decomposition of DCD. Our catalyst exhibits high intrinsic CO reduction activity for CO conversion, with a high Faradaic efficiency (FE up to 97%) and high turnover frequency of 5535 h at a low overpotential of 0.39 V versus reversible hydrogen electrode. Further experiments and density functional theory results demonstrate that the single-atom Bi-N site is the dominating active center simultaneously for CO activation and the rapid formation of key intermediate COOH* with a low free energy barrier.