Capacitive Chemical Sensors Based on Two-Dimensional WSe 2

Abstract

We demonstrated capacitive-type chemical sensors (chemicapacitor sensors) based on two-dimensional (2D) tungsten diselenide (WSe 2 ). The integration of 2D materials with high surface-to-volume ratios and a capacitor resulted in excellent chemical sensing with high selectivity, high sensitivity, and fast response. WSe 2 -based 2D chemicapacitors were fabricated by combining exfoliated WSe 2 flakes with parallel-plate capacitors. The sensing ability of WSe 2 -based 2D chemicapacitors towards NO 2 molecules was characterized by monitoring the changes in capacitance (ΔC/C 0 , ∼65%) and parallel resistance (ΔR p /R p0 , ∼−90%) due to the adsorption of NO 2 molecules (200 ppm). Transient sensing characteristics with fast response and recovery were achieved with adequate reproducibility. Interestingly, ΔC/C 0 and ΔR p /R p0 exhibited different behaviors, which can be a useful value for distinguishing between different target gas molecules. Our novel approach provides a convenient and effective method for producing 2D chemicapacitor sensors at low cost and with low power consumption.