Asymmetric heterostructured SiO2/Al2O3 nanofluidic diodes modulating ionic transport for highly efficient light-gating device

Bioinspired artificial asymmetric nanochannels for more precise controls of ion transport and ion pump at the nanometer scale have been attracting some attention for extensive application in biosensors, ions separation technologies, nanofluidic diodes and energy device. Herein, we construct the first asymmetric heterostructured SiO2/Al2O3 nanofluidic diodes based on the introduction of physical structures and chemical surface activity. Due to asymmetric chemically deposited coatings and surface charges distribution, the SiO2/Al2O3 nanofluidic diodes are capable of regulating ion transport selectivity and possessing ionic current rectification properties. These asymmetric heterostructured SiO2/Al2O3 nanofluidic diodes are further introduced spiropyran into nanochannels to create a lightgating device, which were triggered by ultraviolet light to be “ON” state from the neutral spiropyran blocked “OFF” state. This asymmetric heterostructured SiO2/Al2O3 nanofluidic diode epitomizes high sensitivity, fine selectivity, superior stability and highly reversibility. The combination with photoswitchable compounds spiropyrans shows great promise for easy application in the optical device such as highly sensitive light gating devices.