Laser-induced graphene electrodes for electrochemical ion sensing, pesticide monitoring, and water splitting.

Abstract

Laser-induced graphene (LIG) has shown to be a scalable manufacturing route to create graphene electrodes that overcome the expense associated with conventional graphene electrode fabrication. Herein, we expand upon initial LIG reports by functionalizing the LIG with metallic nanoparticles for ion sensing, pesticide monitoring, and water splitting. The LIG electrodes were converted into ion-selective sensors by functionalization with poly(vinyl chloride)-based membranes containing K+ and H+ ionophores. These ion-selective sensors exhibited a rapid response time (10-15s), near-Nernstian sensitivity (53.0mV/dec for the K+ sensor and - 56.6mV/pH for the pH sensor), and long storage stability for 40days, and were capable of ion monitoring in artificial urine. The pesticide biosensors were created by functionalizing the LIG electrodes with the enzyme horseradish peroxidase and displayed a high sensitivity to atrazine (28.9nA/μM) with negligible inference from other common herbicides (glyphosate, dicamba, and 2,4-dichlorophenoxyacetic acid). Finally, the LIG electrodes also exhibited a small overpotential for hydrogen evolution reaction and oxygen evolution reaction. The oxygen evolution reaction tests yielded overpotentials of 448mV and 995mV for 10mA/cm2 and 100mA/cm2, respectively. The hydrogen evolution reaction tests yielded 35mV and 281mV for the corresponding current densities. Such a versatile LIG platform paves the way for simple, efficient electrochemical sensing and energy harvesting applications.