Edge-enriched WS nanosheets on carbon nanofibers boosts NO detection at room temperature.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) hold great promise for room temperature (RT) NO sensors. However, the exposure of the edges of TMDs with high adsorption capability and electronic activity remains a great obstacle to achieve high sensor sensitivity. Herein, we demonstrate a high-performance RT NO gas sensor based on WS nanosheets/carbon nanofibers (CNFs) composite with abundant intentionally exposed WS edges. Few-layer WS nanosheets are anchored on CNFs through a hydrothermal process. The approach permits to achieve a coating presenting an optimized active surface area and accessibility of the sensing layers. The exposure of WS edges remarkably improves the sensing properties. Consequently, the WS@CNFs composite exhibits excellent selectivity to NO at RT with improved response and much lower detection limit in comparison to the WS and CNFs counterparts. Density functional theory (DFT) calculations verify a surprisingly strong NO adsorption on WS edge sites (adsorption energy 3.40 eV) with a partial charge transfer of 0.394e, while a week adsorption on the basal surface of WS (adsorption energy 0.25 eV) with a partial charge transfer of 0.171e. The strategy proposed herein will be instructive to the design of efficient material structures for low-power NO sensors with optimized performances.