In Situ Grown Ultrafine RuO2 Nanoparticles on GeP5 Nanosheets as the Electrode Material for Flexible Planar Micro-Supercapacitors with High Specific Capacitance and Cyclability.

GeP5, as the most representative phosphorus-based material in two-dimensional layered phosphorous compounds, has shown a fairly bright application prospect in the field of energy storage because of its ultrahigh electrical conductivity. However, high-yield exfoliation methods and effective structure construction strategies for GeP5 nanosheets are still missing, which completely restricts the further application of GeP5-based nanocomposites. Here, we not only improved the yield of GeP5 nanosheets by a liquid nitrogen-assisted liquid-phase exfoliation technique but also constructed the GeP5@RuO2 nanocomposites with the 0D/2D heterostructure by in situ introduction of ultrafine RuO2 nanoparticles on highly conductive GeP5 nanosheets using a simple hydrothermal synthesis method, and then applying it to micro-supercapacitors (MSCs) as electrode materials through a mask-assisted vacuum filtration technique. It is precisely because of the synergy of the electrical double-layer material, GeP5 nanosheets and the pseudocapacitance material RuO2 nanoparticles that endows the GeP5@RuO2 electrode with outstanding electrochemical performance in micro-supercapacitors with a large specific capacitance of 129.5 mF cm-2/107.9 F cm-3, high energy density of 17.98 μWh cm-2, remarkable long-term cycling stability with 98.4% capacitance retention after 10 000 cycles, the exceptional mechanical stability, outstanding environmental stability, and excellent integration features. This work opens up a new avenue to construct GeP5-based nanocomposites as a most promising novel electrode material for practical application in flexible portable/wearable micro-nanoelectronic devices.