Systematic investigation of the piezocatalysis–adsorption duality of polymorphic MoS2 nanoflowers

This study theoretically and experimentally investigates the piezocatalytic and adsorption effects of different phases of polymorphic 1T MoS2 NFs. Piezoresponse force microscopy indicates a considerably high piezoelectric potential (piezopotential) at the few-layer 2H MoS2 NFs (40 mV), which is eight times higher than that at the few-layer MoS2 NFs (4.9 mV). This finding is confirmed by calculations based on density functional theory (DFT) and the finite element method (FEM). To verify whether the polymorphic MoS2 NFs would exhibit adsorption or piezocatalytic effects, the electrostatic surface charge of these NFs and the RhB solution is varied using sodium hydroxide and nitric acid solutions. The cationic dye is adsorbed on the surfaces of the 1T MoS2 NFs; however, the few-layer 2H MoS2 NFs generate a considerable quantity of hydroxyl species for degrading RhB molecules through the mechanical-force-induces piezopotential. This study discovers that the polymorphic MoS2 NFs exhibit a piezocatalysis–adsorption duality.