Assembling Metal Organic Layer Composites for High-Performance Electrocatalytic CO Reduction to Formate.

2D metal-organic-framework (MOF) based composites have emerged as promising candidates for electrocatalysis due to their high structural flexibility and fully exposed active sites. Herein, a freestanding metal-organic layer (MOL) with a 2D kgd (kagome dual) lattice was constructed with abundant surface oxygenate groups serving as anchoring sites to immobilize diverse guests. Taking Bi as an example, tetragonal Bi O nanowires can be uniformly grown on MOLs after solvothermal treatment, the structural evolution of which was followed by ex situ electron microscopy. The as-prepared Bi O /MOL exhibits excellent CO electroreduction activity towards formate reaching a specific current of 2.3 A mg and Faradaic efficiencies of over 85 % with a wide potential range from -0.87 to -1.17 V, far surpassing Bi O /UiO (a 3D Zr -oxo based MOF) and Bi O /AB (Acetylene Black). Such a post-synthetic modification strategy can be flexibly extended to develop versatile MOL composites, highlighting the superiority of optimizing MOL-based composites for electrocatalysis.