In this work, the structural, electronic and optical properties of novel atomically thin systems based on germanene and antimonene nanocomposites have been investigated by means of density functional theory. We find that the germanene and antimonene monolayers are bound to each other via orbital hybridization with enhanced binding strength. Most importantly, the band gap opening can be achieved. Our results demonstrate that the AAII pattern has a direct band gap characteristic with a moderate value of up to 391 meV, while the other three patterns have indirect band gaps tunable from 37 to 171 meV. In particular, changing the direction and strength of the external electric field (E-field) can effectively tune the energy gap of the germanene/antimonene bilayer over a wide range even with a semiconductor–metal transition. The work function of the heterobilayer in the AAII pattern which possesses a direct band gap can be tinkered up from −3.21 to 12.33 eV by applying different E-field intensities. In addition, the germanene/antimonene bilayer exhibits more pronounced optical conductivity. The tunable bandgaps and work function together with a superior visible light response capability make the germanene/antimonene bilayer a viable candidate for optoelectronic applications.

Sensitivity and pressure range are two significant parameters of pressure sensors. Existing pressure sensors have difficulty achieving both high sensitivity and a wide pressure range. Therefore, we propose a new pressure sensor with a ternary nanocomposite Fe₂O₃/C@SnO₂. The sea urchin-like Fe₂O₃ structure promotes signal transduction and protects Fe₂O₃ needles from mechanical breaking, while the acetylene carbon black improves the conductivity of Fe₂O₃. Moreover, one part of the SnO₂ nanoparticles adheres to the surfaces of Fe₂O₃ needles and forms Fe₂O₃/SnO₂ heterostructures, while its other part disperses into the carbon layer to form SnO₂@C structure. Collectively, the synergistic effects of the three structures (Fe₂O₃/C, Fe₂O₃/SnO₂ and SnO₂@C) improves on the limited pressure response range of a single structure. The experimental results demonstrate that the Fe₂O₃/C@SnO₂ pressure sensor exhibits high sensitivity (680 kPa⁻¹), fast response (10 ms), broad range (up to 150 kPa), and good reproducibility (over 3500 cycles under a pressure of 110 kPa), implying that the new pressure sensor has wide application prospects especially in wearable electronic devices and health monitoring.