Defect-Rich 2D Material Networks for Advanced Oxygen Evolution Catalysts

A versatile and straightforward room-temperature strategy is demonstrated to synthesize boundary defect-rich ultrathin transition metal hydroxide nanosheet networks by in situ etching of a cobalt metal–organic framework (Co-MOF, ZIF-L-Co). The resultant defect-rich ultrathin Co(OH)2 (D-U-Co(OH)2) nanoarray is one of the most active monometal-based oxygen evolution catalysts to date. Its activity is 3–4 times higher than that of the commercial RuO2 and superior to that of the reported exfoliated bimetallic catalysts. Co-MOF can also be grown on various substrates, and the chemical composition of the defect-rich 2D materials is tunable by changing the metal ions in the etchants. Owing to these merits of the unique synthesis route, our work provides an opportunity for synthesizing advanced nanomaterials that are difficult to get access to by conventional methods.