Efficient hydrogen production using Ni-graphene oxide-dispersed laser-engraved 3D carbon micropillars as electrodes for microbial electrolytic cell

A nickel (Ni)-graphene oxide (GO) dispersed carbon film was prepared by the carbonization of the phenolic precursor-based polymer. Three dimensional (3D) micropillars were fabricated on the carbon film using laser ablation technique. The micropillars-engraved film was used as electrodes in a single chamber microbial electrolytic cell (MEC) for hydrogen (H-2) production. Besides promoting biofilm formation at anode, the 3D micropillars provided relatively more exposure to the in situ dispersed electrocatalytic Ni nanoparticles (NPs) and electroconductive GO in the carbon film. The Tafel slope of similar to 49 mV dec(-1) indicated that Heyrovsky reaction or electrochemical desorption was the rate determining step for H-2 evolution. A H-2 production rate of 4.22 +/- 0.21 m(3)m(-3)d(-1) was measured at 0.8V in the prepared electrode-based MEC. Whereas the overall H-2 and cathodic recoveries were measured to be 92.3 +/- 2.77% and 98.7 +/- 0.99%, respectively, the Coulombic and overall energy efficiencies were determined to be 93.5 +/- 2.81% and 72.2 +/- 3.61%, respectively. The relatively higher efficiency of the MEC was ascribed to the synergistic contributions of the 3D micropillars, Ni NPs and GO, indicating the prepared electrode to be a viable alternative to the expensive noble metal-based electrodes used in MECs for H-2 production. (C) 2019 Elsevier Ltd. All rights reserved.