Gas Sensing Mechanisms in Two-Dimensional Materials

Two-dimensional materials, comprising atomically thin layers of elements or compounds, offer exceptional surface-to-volume ratios and tunable electronic structures that render them highly sensitive to surrounding gas species. Gas sensing in these materials primarily relies on the interaction between gas molecules and the sensing layer, which can occur via physisorption or chemisorption. Physisorption involves weak van der Waals forces and often leads to reversible adsorption with modest changes in electrical conductivity, whereas chemisorption entails the formation of chemical bonds and larger, more persistent shifts in charge distribution and carrier mobility. Charge transfer between adsorbed molecules and the 2D substrate modulates the local carrier concentration, altering resistance, capacitance or optical properties. Strategies to enhance selectivity and sensitivity include defect engineering, heteroatom doping, creation of heterojunctions and application of external electric fields. Field-effect transistor architectures enable real-time monitoring of conductance changes under gate bias, while sensor arrays exploit distinctive response patterns for multiple gas identification. The capacity to operate at room temperature with low power consumption, combined with compatibility with flexible electronics, positions 2D material sensors for widespread deployment in environmental monitoring, industrial safety and medical diagnostics.

Research from Nature Portfolio

Recent studies have demonstrated that ultrathin phosphorene nanosheets integrated into field-effect transistor platforms achieve record sensitivity to nitrogen dioxide at parts-per-billion levels under ambient conditions. It was found that the sensing performance depends critically on layer thickness: nanosheets thinner than 10 nm exhibit enhanced band-gap modulation, while thicker sheets offer a greater number of adsorption sites. First-principles calculations combined with thermodynamic modelling show that the optimum thickness balances carrier mobility and adsorption density, yielding rapid, reversible responses in real-time sensing.

Gas Sensing Mechanisms in Two-Dimensional Materials publication trend

The graph below shows the total number of articles in gas sensing mechanisms in two-dimensional materials across all publications each year (not limited to Nature Index journals).

Technical terms

Two-dimensional materials: Crystalline nanosheets one or few atoms thick with high surface exposure.

Transition metal dichalcogenides (TMDs): Layered compounds formed by transition metals bonded to chalcogen atoms.

Physisorption: Weak adsorption of molecules via van der Waals interactions.

Chemisorption: Adsorption involving chemical bond formation and significant charge reorganisation.

Field-effect transistor (FET): Electronic device where an applied gate voltage modulates channel conductance.

Adsorption energy: Energetic change when a gas molecule binds to a surface.

Charge transfer: Movement of electrons between an adsorbed species and the sensing material.

References

1. Toward high selectivity of sensor arrays: Enhanced adsorption interaction and selectivity of gas detection (N2, O2, NO, CO, CO2, NO2, SO2, AlH3, NH3, and PH3) on transition metal dichalcogenides (MoS2, MoSe2, and MoTe2). Acta Materialia (2024).
2. Ultrahigh sensitivity and layer-dependent sensing performance of phosphorene-based gas sensors. Nature Communications (2015).
3. A DFT Study on the Adsorption of H2S and SO2 on Ni Doped MoS2 Monolayer. Nanomaterials (2018).
4. Graphene-like BC6N nanosheets are potential candidates for detection of volatile organic compounds (VOCs) in human breath: A DFT study. Applied Surface Science (2021).