Efficient CO₂ reduction MOFs derivatives transformation mechanism revealed by in-situ liquid phase TEM

Materials derived from MOFs have great potentials in energy conversion. However, the nanoscale transformation processes of MOFs derivatives remain unknown. Herein, by using in-situ liquid phase TEM, we directly visualize the MOFs etching processes. For the first time, unexpected nanobubble stability controlled transformation mechanism of ZIF-67 to porous or layered cobalt transition metal hydroxide (Co-TMH) is identified. Voids in MOFs migrate and merge to form nanobubbles due to structural collapse. Under slow diffusion conditions, nanobubbles move slowly and Co-TMH clusters generate on the nanobubble interface, further favoring the formation of internal nanocages and porous structures. On the other hand, a fast diffusion leads to rapid nanobubbles generation, aggregation and reshaping, inducing layered structure formation. Inspired by in-situ observation, we further synthesize porous Co-TMH at − 80 ℃ under inhibited diffusion conditions, which exhibits excellent catalytic performance on CO₂ reduction reaction.