Interfacial engineered biomass-derived G/VMT-PCNCs networks as high-performance proton-conducting humidity sensors

In this study, a novel proton-conducting film was strategically engineered by interfacial manipulation of green and sustainable biomass resources guanine and phosphorylated cellulose nanocrystals (PCNCs) within vermiculite layers. The interfacial engineering approach involved regulation of molecular interactions at the vermiculite-organic interface, whereby PCNCs were incorporated into the interlayers of guanine/vermiculite composites. This interfacial assembly process guided guanine to form tubular structures or ultrathin nanosheets architectures, enabling the fabrication of guanine/vermiculite-PCNCs (G/VMT-PCNCs) composite films with an active-site-rich and tightly interconnected network via a vacuum-assisted process. The rationally designed composite films exhibited excellent proton conductivity, which showed positive correlation with relative humidity (RH) and temperature, reaching 0.50 mS/cm at 25 °C and 97 %. Notably, the optimal composite film achieved a maximum proton conductivity of 1.15 mS/cm at 97 % RH and 80 °C. The interface-engineered structure endowed the humidity sensors based on this composite film with superior performance, including high sensitivity (31.82 Hz/%RH), small hysteresis (0.60 % RH), and rapid response/recovery times (36 s/5 s). The findings provide valuable insights into the design and fabrication of high-performance proton exchange films and humidity sensors, contributing to the advancement of sustainable clean energy technologies.