Rapid, all dry microfabrication of three-dimensional Co₃O₄/Pt nanonetworks for high-performance microsupercapacitors

On-chip electrochemical energy storage devices have attracted growing attention due to the decreasing size of electronic devices. Various approaches have been applied for constructing the microsupercapacitors. However, the microfabrication of high-performance microsupercapacitors by conventional and fully compatible semiconductor microfabrication technologies is still a critical challenge. Herein, unique three-dimensional (3D) Co₃O₄ nanonetwork microelectrodes formed by the interconnection of Co₃O₄ nanosheets are constructed by controllable physical vapor deposition combined with rapid thermal annealing. This construction process is an all dry and rapid (≤5 minutes) procedure. Afterward, by sputtering highly electrically conductive Pt nanoparticles on the microelectrodes, the 3D Co₃O₄/Pt nanonetworks based microsupercapacitor is fabricated, showing a high volume capacitance (35.7 F cm^-3) at a scan rate of 20 mV s^-1 due to the unique interconnected structures, high electrical conductivity and high surface area of the microelectrodes. This microfabrication process is also used to construct high-performance flexible microsupercapacitors, and it can be applied in the construction of wearable devices. The proposed strategy is completely compatible with the current semiconductor microfabrication and shows great potential in the applications of the large-scale integration of micro/nano and wearable devices.