Co 3 O 4 nanosheet-built hollow dodecahedrons via a two-step self-templated method and their multifunctional applications

The Co 3 O 4 nanosheet-built hollow dodecahedrons (Co 3 O 4 NSHDs) were fabricated via a controllable twostep self-templated method. The ZIF-67 dodecahedrons were prepared as first self-template to synthesize the Co-LDH hollow dodecahedrons, which were further used as self-template to fabricate Co 3 O 4 NSHDs by a controlled calcination. The proposed two-step self-templated method not only brings hollow structures without auxiliary template, ultrathin nanosheet, ultrafine grains, and large surface areas, but also allows the easy and uniform surface modification, as demonstrated of PdO modification. The Co 3 O 4 NSHDs with above features could show multifunctional applications, such as sensing and catalysis. Experiments suggest that the Co 3 O 4 NSHDs show good gas sensing performances to trimethylamine at a low operating temperature (100°C). They can be further enhanced by PdO surface modification, which have a low detection limit (250 ppb) and a short response time (4.5 s). In addition, the Co 3 O 4 NSHDs exhibited excellent oxygen evolution reaction performances with a low overpotential of 359 mV, low Tafel slope of 80.7 mV dec −1 and low electrochemical impedance, which was superior to those for the Co 3 O 4 NCs obtained by directly calcinating the ZIF-67 templates, Ni foam and most common metal oxides catalysts.