NH Sensor Based on 2D Wormlike Polypyrrole/Graphene Heterostructures for a Self-Powered Integrated System.

The rapid development of a NH sensor puts forward a great challenge for active materials and integrated sensing systems. In this work, an ultrasensitive NH sensor based on two-dimensional (2D) wormlike mesoporous polypyrrole/reduced graphene oxide (w-mPPy@rGO) heterostructures, synthesized by a universal soft template method is reported, revealing the structure-property coupling effect of the w-mPPy/rGO heterostructure for sensing performance improvement, and demonstrates great potential in the integration of a self-powered sensor system. Remarkably, the 2D w-mPPy@rGO heterostructrure exhibits preferable response toward NH (Δ/ = 45% for 10 ppm NH with a detection limit of 41 ppb) than those of the spherical mesoporous hybrid (s-mPPy@rGO) and the nonporous hybrid (n-PPy@rGO) due to its large specific surface area (193 m/g), which guarantees fast gas diffusion and transport of carriers. Moreover, the w-mPPy@rGO heterostructures display outstanding selectivity to common volatile organic compounds (VOCs), HS, and CO, prominent antihumidity inteference superior to most existing chemosensors, superior reversibility and favorable repeatability, providing high potential for practicability. Thus, a self-powered sensor system composed of a nanogenerator, a lithium-ion battery, and a w-mPPy@rGO-based sensor was fabricated to realize wireless, portable, cost-effective, and light-weight NH monitoring. Impressively, our self-powered sensor system exhibits high response toward 5-40 mg NHNO, which is a common explosive to generate NH via alkaline hydrolysis, rendering it a highly prospective technique in a NH-based sensing field.