Unfolding the hydrogen gas sensing mechanism across 2D Pnictogen/graphene heterostructure sensors

We have developed unique nanoengineered bi-stacked layers based on 2D Pnictogens and graphene (G) sheets via photolithography. Amongst the Pnictogen class (phosphorene/G (P/G), antimonene/G (Sb/G), arsenene/G (As/G), and bismuthine/G (Bi/G), hybrid Sb/G demonstrated excellent gas response towards H2 (∼4-fold improvement), high selectivity, fast response/recovery times (>3 fold reduction), and ultra-low limit of detection (LOD: 0.05 ppm) over pristine Sb or G sensors. Amongst others, LOD of P/G was comparable to that of Sb/G while it degraded for As/G and Bi/G heterostructures. The density functional theory (DFT) calculations demonstrated a Bader charge transfer mechanism from Sb/G heterojunction towards H2 gas, modulating the potential barrier from Ohmic to Schottky type. The outstanding gas sensing performance of the Sb/G sensor places it amongst highly selective and fast hydrogen sensors amongst Pnictogen-graphene family.