Capacitive Chemical Sensors Based on Two-Dimensional WSe2

Abstract

We demonstrated capacitive-type chemical sensors (chemicapacitor sensors) based on two-dimensional (2D) tungsten diselenide (WSe2). 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. WSe2-based 2D chemicapacitors were fabricated by combining exfoliated WSe2 flakes with parallel-plate capacitors. The sensing ability of WSe2-based 2D chemicapacitors towards NO2 molecules was characterized by monitoring the changes in capacitance (Delta C/C-0, similar to 65%) and parallel resistance (Delta R-p/R-p0, similar to-90%) due to the adsorption of NO2 molecules (200 ppm). Transient sensing characteristics with fast response and recovery were achieved with adequate reproducibility. Interestingly, Delta C/C-0 and Delta R-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. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.