Multifunctional Nanostructured ZnO/MoS2/rGO for CO2 Photoelectrochemical Sensing and Flexible Solid-State Symmetrical Supercapacitors

Hybrid transition metal oxides and redox graphene nanocomposites are ideal materials for electrochemical sensors and energy storage devices. Nevertheless, the successful synthesis of materials with excellent electrochemical properties and good synergistic catalytic properties is still facing significant challenges. In this article, the multistep hydrothermal method was used to synthesize the excellent performance of the 3-D nanoflower-like ZnO/MoS2/rGO composite, which successfully overcame the above challenges and improved the all-around performance of ZnO/MoS2/rGO nanocomposites. The material has been studied in the novel dual-function electrode materials of solid-state flexible supercapacitors and amperometric photochemical CO2 gas sensors. For CO2 gas-sensitive applications, the ZnO/MoS2/rGO sensor shows an excellent linear sensing range (10–7820 ppm) for CO2 under illumination, with good sensitivity (
$10.23 \mu \text{A}\cdot $
ppm
$^{-{1}}\cdot $
cm
$^{-{2}}$
), short recovery, and current response time (< 10 s) and low detection limit (10 ppm). In addition, ZnO/MoS2/rGO electrodes exhibit high specific capacitance of about 3742
$\text{F}\cdot \text{g}^{-{1}}$
at 2
$\text{A}\cdot \text{g}^{-{1}}$
(specific capacity of 519.72 mAh
$\cdot \text{g}^{-{1}}$
), and significant rate performance (2000
$\text{F}\cdot \text{g}^{-{1}}$
at 20
$\text{A}\cdot \text{g}^{-{1}}$
), and long cycle life. These excellent performance characteristics indicate that ZnO/MoS2/rGO nanocomposites have great potential for a new generation of electrochemical gas sensors and high-performance energy storage.