High-efficiency hydrogen detection for Sc decorated biphenylene based gas sensors: Insights from DFT study

Efficient and rapid detection of hydrogen during transport can effectively prevent gas leaks and explosions. Inspired by the successful synthesis of biphenylene network (BPN) monolayer, the electronic structure and sensing characteristics of nanodevices with metal Sc-decorated BPN monolayer for different concentrations of H2 are investigated by using density-functional theory in combination with the nonequilibrium Green's function approach theoretically and systematically. Calculated electron localization functions, charge transfers, energy band structures, projected densities of states, charge difference densities and adsorption energies revealed that the adsorption of H2 by metal Sc-modified BPN monolayer are all chemisorbed. Furthermore, compared to the original BPN transport device, the modification of Sc metal enhances electronic transport while preserving the anisotropy of the electron transport along the zigzag and armchair directions. The metallicity gradually enhanced with increasing concentration of Sc adsorbed by BPN. Interestingly, the BPN-Sc system exhibits a pronounced negative differential resistance (NDR) effect along the armchair direction, and it achieves switching ratios of 3.65 × 105 and 1.98 × 105 for its D-5H2 and D-1H2 devices. In addition, the maximum rectification ratio of the D-1H2 device in the armchair direction reaches ∼107 at low hydrogen concentration. Critically, the short recovery time (0.1 μs) demonstrates that the device can be reused when adsorbing individual H2. These results indicate the potential use of BPN with adsorbed Sc in the domain of gas sensitivity, especially for applications in detecting low concentration H2 leakage sensors, providing a theoretical basis.