Efficient Water-Splitting Electrodes Based on Laser-Induced Graphene

Electrically splitting water to H₂ and O₂ is a preferred method for energy storage as long as no CO₂ is emitted during the supplied electrical input. Here we report a laser-induced graphene (LIG) process to fabricate efficient catalytic electrodes on opposing faces of a plastic sheet, for the generation of both H₂ and O₂. The high porosity and electrical conductivity of LIG facilitates the efficient contact and charge transfer with the requisite electrolyte. The LIG-based electrodes exhibit high performance for hydrogen evolution reaction and oxygen evolution reaction with excellent long-term stability. The overpotential reaches 100 mA/cm² for HER, and OER is as low as 214 and 380 mV with relatively low Tafel slopes of 54 and 49 mV/dec, respectively. By serial connecting of the electrodes with a power source in an O-ring setup, H₂ and O₂ are simultaneously generated on either side of the plastic sheet at a current density of 10 mA/cm² at 1.66 V and can thereby be selectively captured. The demonstration provides a promising route to simple, efficient, and complete water splitting.